Integrated electro-optical device for electrical characterization and laser annealing

Abstract

An apparatus includes an optical device and an electrical characterization device. The optical apparatus and the electrical characterization apparatus include an integrated configuration to perform a laser annealing operation for tuning a junction resistance of the superconducting tunnel junction device on the quantum chip, and to perform an in-situ resistance measurement to measure the junction resistance of the superconducting tunnel junction device on the quantum chip.

Description

BACKGROUND

[0001] The present disclosure relates generally to techniques for tuning Josephson junction devices, and in particular, to laser annealing systems and techniques for tuning the tunnel junction resistance of Josephson junction devices. Quantum computing systems can be implemented using a superconducting circuit quantum electrodynamics (cQED) architecture, which is built using quantum circuit components such as, for example, superconducting qubits (e.g., fixed frequency transmon qubits), superconducting quantum interference devices (SQUIDs), and other types of superconducting devices including Josephson junction devices. In particular, superconducting qubits are electronic circuits implemented using components such as superconducting tunnel junctions (e.g., Josephson junctions), inductors, and / or capacitors, and behave like quantum mechanical anharmonic (nonlinear) oscillators with quantized states when cooled to low temperatures. Fixed frequency qubits (e.g., transmon qubits) have a transition frequency (denoted as f and a first excited state corresponding to the energy difference between the ground state 01 and the first excited state 01 of the qubit. The transition frequency f J of the qubit is known to be estimable from the tunnel junction resistance (denoted as R

[0002] Solid state quantum processors can include a plurality of superconducting qubits arranged in a given lattice structure (e.g., square lattice, hexagonal lattice) to enable quantum information processing by quantum gate operations (e.g., single qubit gate operations and multi-qubit gate operations), where the quantum information is generated and encoded in the computational ground state (e.g., and ) of individual qubits, superpositions of the computational ground states of individual qubits, and / or entangled states of multiple qubits. Ongoing technological advances in quantum processor design are enabling rapid scaling of the physical number of superconducting qubits and the computational power of quantum processors. Indeed, while the current state-of-the-art quantum processors have greater than 50 qubits, it is expected that future quantum processors will have many more qubits, e.g., hundreds or thousands of qubits, or more.

[0003] Scaling the number of qubits (e.g., fixed-frequency transmon qubits) in a qubit lattice while maintaining high-fidelity quantum gate operations remains a key challenge for quantum computing. For example, as superconducting quantum processors scale to more qubits, frequency crowding within the qubit lattice becomes increasingly problematic as it is necessary to precisely control the qubit transition frequencies to minimize gate errors that can arise from lattice frequency collisions (e.g., incorrect detuning between superconducting qubits can degrade the fidelity of multi-qubit gate entangling operations). However, due to semiconductor processing variability, the transition frequencies of fabricated superconducting qubits can deviate from design targets.

[0004] In this regard, laser annealing techniques can be utilized to adjust qubit frequencies after fabrication to selectively tune fixed-frequency qubits of a given qubit lattice to a desired frequency pattern. In particular, laser annealing techniques can be utilized to selectively trim (i.e., tune) individual qubit frequencies after fabrication by enabling local thermal annealing of the Josephson junctions of the qubits to adjust and stabilize the tunnel junction resistance R J (and correspondingly, the respective qubit transition frequency f 01 ) of the respective Josephson junctions with high precision to increase the collision-free yield of fixed-frequency qubit lattices. However, due to, for example, inherent variability of the laser thermal annealing process itself and / or the devices used to perform such laser thermal annealing after fabrication to tune qubit transition frequencies in a given qubit lattice, tuning qubit transition frequencies by laser thermal annealing is not trivial. SUMMARY

[0005] Exemplary embodiments of the present disclosure include a laser annealing apparatus for laser tuning the junction resistance of a superconducting tunnel junction device (e.g., a Josephson junction).

[0006] Exemplary embodiments include an apparatus comprising an optical apparatus and an electrical characterization apparatus. The optical apparatus and the electrical characterization apparatus comprise an integrated configuration to perform laser annealing operations for tuning the junction resistance of a superconducting tunnel junction device on a quantum chip and to perform in-situ resistance measurements to measure the junction resistance of the superconducting tunnel junction device on the quantum chip.

[0007] Advantageously, the integration of optical and electrical characterization devices enables in-situ operation for laser annealing and measuring junction resistance, such as that of a Josephson junction, to support laser tuning operations (e.g., tracking the tuning progress of multiple laser annealing iterations), thereby improving the accuracy and throughput of laser tuning operations. For example, the integration of laser tuning and in-situ electrical characterization enables increased throughput and scaling of laser tuning processes (e.g., LASIQ processes for laser annealing of Josephson junctions for superconducting qubits to tune (e.g., adjust) the transition frequencies of superconducting qubits).

[0008] Another exemplary embodiment includes a system comprising a control system and a laser annealing apparatus coupled to the control system. The laser annealing apparatus includes an integrated configuration of optical and electrical characterization devices. The control system controls the laser annealing apparatus to perform laser annealing operations for tuning the junction resistance of a superconducting tunnel junction device on a quantum chip, and performs in-situ resistance measurements to measure the junction resistance of the superconducting tunnel junction device on the quantum chip.

[0009] Another exemplary embodiment includes a method comprising performing an annealing operation to tune the junction resistance of a superconducting tunnel junction device on a quantum chip, wherein performing the annealing operation comprises: performing a thermal annealing operation to heat the quantum chip and thermally anneal the superconducting tunnel junction device to partially adjust the junction resistance of the superconducting tunnel junction device to a corresponding target junction resistance of the superconducting tunnel junction device; performing a resistance measurement of the superconducting tunnel junction device after the thermal annealing operation to measure the corresponding junction resistance of the superconducting tunnel junction device; and performing a laser annealing operation on the superconducting tunnel junction device to adjust the junction resistance of the superconducting tunnel junction device from its corresponding measured junction resistance to its corresponding target junction resistance.

[0010] Another exemplary embodiment includes a method comprising performing a laser tuning process using a laser annealing apparatus to tune the junction resistance of a superconducting tunnel junction device on a quantum chip, the laser annealing apparatus performing a laser annealing operation to laser tune the junction resistance of the superconducting tunnel junction device, and performing an in-situ resistance measurement to measure the junction resistance of the superconducting tunnel junction device on the quantum chip.

[0011] Another exemplary embodiment includes a computer program product for laser tuning. The computer program product includes one or more computer-readable storage media and program instructions commonly stored on the one or more computer-readable storage media. The program instructions include instructions for performing a laser tuning process using a laser annealing apparatus to tune the junction resistance of a superconducting tunnel junction device on a quantum chip, the laser annealing apparatus performing a laser annealing operation to laser tune the junction resistance of the superconducting tunnel junction device, and performing an in-situ resistance measurement to measure the junction resistance of the superconducting tunnel junction device on the quantum chip.

[0012] In another exemplary embodiment, as may be combined with the foregoing paragraphs, the electrical characterization device is configured to perform a direct current (DC) resistance measurement operation to measure the junction resistance of a superconducting tunnel junction device.

[0013] In another exemplary embodiment, as may be combined with the foregoing paragraphs, the electrical characterization device is configured to perform an alternating current (AC) resistance measurement operation to measure the junction resistance of a superconducting tunnel junction device.

[0014] In another exemplary embodiment, as may be combined with the foregoing paragraphs, the electrical characterization apparatus includes a wafer probe, wherein the wafer probe includes at least one of an automated and a semi-automated wafer probing system.

[0015] In another exemplary embodiment, as may be combined with the foregoing paragraphs, the electrical characterization device includes an environmental chamber configured to control the environment surrounding the quantum chip during laser annealing operations.

[0016] In another exemplary embodiment, as may be combined with the foregoing paragraphs, the environment chamber is configured to control the environment by at least one of (i) controlling the composition of one or more gases within the environment chamber and (ii) generating a vacuum within the environment chamber.

[0017] In another exemplary embodiment, as may be combined with the foregoing paragraphs, the electrical characterization device includes a thermal control system configured to (i) heat the quantum chip to perform a bulk thermal annealing operation for adjusting the junction resistance of the tunnel junction device of the quantum chip, and (ii) cool the quantum chip to perform at least one of in-situ resistance measurements.

[0018] Other embodiments will be described in the following detailed description of exemplary embodiments, which should be consistent with the appendix. Figure One Start reading. Attached Figure Description

[0019] Figure 1 A laser annealing system according to an exemplary embodiment of the present disclosure is schematically illustrated.

[0020] Figure 2A A laser annealing apparatus including a modular optical scope unit is schematically illustrated according to an exemplary embodiment of the present disclosure.

[0021] Figure 2B This is a perspective view of a modular optical lens barrel unit according to an exemplary embodiment of the present disclosure.

[0022] Figure 2C A flowchart is shown illustrating a method for performing laser tuning operations using a laser annealing apparatus including a modular optical barrel unit, according to an exemplary embodiment of the present disclosure.

[0023] Figure 3A A laser annealing system according to another exemplary embodiment of the present disclosure is schematically illustrated.

[0024] Figure 3B The illustration schematically shows an exemplary embodiment of the present disclosure that can be implemented... Figure 3A The optical system implemented in the laser annealing system.

[0025] Figure 4 A laser annealing system according to another exemplary embodiment of the present disclosure is schematically illustrated.

[0026] Figure 5 A flowchart is shown of a method for tuning a Josephson junction of a qubit device based on a tuning scheme, according to an exemplary embodiment of the present disclosure.

[0027] Figure 6 A flowchart is shown of a method for performing an iterative laser annealing process to progressively adjust the junction resistance of a Josephson junction to a corresponding target junction resistance, according to an exemplary embodiment of the present disclosure.

[0028] Figure 7A A flowchart is shown of a method for focusing and aligning to a target Josephson junction in order to perform in-situ Josephson junction resistance measurement according to an exemplary embodiment of the present disclosure.

[0029] Figure 7B A flowchart is shown of a method for performing contact resistance and contact stability checks before performing in-situ Josephson junction resistance measurements, according to an exemplary embodiment of the present disclosure.

[0030] Figure 7C A flowchart illustrating a method for focusing and aligning to a target Josephson junction in order to perform a laser annealing process, according to an exemplary embodiment of the present disclosure, is shown.

[0031] Figure 7D The process of aligning a contact probe and a laser point with a Josephson junction of qubits according to an exemplary embodiment of the present disclosure is illustrated schematically.

[0032] Figure 8A This is a flowchart of a method for performing an annealing operation to tune the junction resistance of a Josephson junction by combining a laser annealing apparatus with in-situ DC resistance measurement, according to an exemplary embodiment of the present disclosure.

[0033] Figure 8B This is a flowchart of a method for performing an annealing operation to tune the junction resistance of a Josephson junction by combining a laser annealing apparatus with in-situ DC resistance measurement, according to another exemplary embodiment of the present disclosure.

[0034] Figure 9 This is a flowchart of a method for performing an annealing operation to tune the junction resistance of a Josephson junction by combining a laser annealing apparatus with in-situ AC resistance measurement, according to an exemplary embodiment of the present disclosure.

[0035] Figure 10 An example architecture of a computing environment for implementing a control system according to an exemplary embodiment of the present disclosure is illustrated, the control system being configured to control a laser annealing system for tuning a Josephson junction. Detailed Implementation

[0036] Regarding laser annealing apparatus and techniques for laser tuning of the junction resistance of superconducting tunnel junction devices (e.g., Josephson junctions of superconducting qubit devices) using a laser annealing device, exemplary embodiments of the present disclosure will now be described in more detail. Generally, exemplary embodiments of the present disclosure include a laser annealing apparatus comprising optical and electrical characterization devices. The optical and electrical characterization devices are integrated to perform laser annealing operations to tune the junction resistance of the superconducting tunnel junction device on a quantum chip, and to perform in-situ resistance measurements to measure the junction resistance of the superconducting tunnel junction device on the quantum chip.

[0037] More specifically, in some embodiments, optical devices are used for laser annealing operations and optical characterization. Laser annealing operations include, for example, generating a laser beam, performing beam shaping to generate a desired laser spot pattern for laser annealing, controlling the laser beam exposure time to control the annealing time, etc. Optical characterization includes, for example, enabling computer vision inspection of the device being laser annealed, and performing imaging and pattern recognition to support alignment of the target device with the laser spot pattern for laser annealing, and aligning the electrical probes of the electrical characterization device with the contacts of the target device for electrical characterization operations (e.g., measuring the junction resistance of a Josephson junction), etc. Furthermore, in some embodiments, the electrical characterization devices are configured to enable, for example, electrical characterization of the target device (e.g., a Josephson junction) before, during, and after laser tuning. For example, integration of the electrical characterization devices enables in-situ resistance measurements to be performed during iterative laser annealing operations on the Josephson junction to track the progress of the junction resistance of the Josephson junction toward a corresponding target junction resistance.

[0038] In some embodiments of the laser annealing apparatus, the optical unit includes a discrete optical configuration (e.g., a benchtop configuration) comprising separate laser and imaging units optically coupled together. The laser unit includes a laser source and optical components for controlling the laser annealing operation (e.g., generating and shaping a laser beam to form a desired laser beam dot pattern for laser annealing, controlling the laser beam exposure time to control the annealing time, etc.). The imaging unit is configured to image the sample within the field of view of the laser unit to enable, for example, computer vision inspection and alignment operations.

[0039] In some embodiments of the laser annealing apparatus, the optical device includes a laser unit and a modular optical barrel unit (e.g., a modular microscope unit), wherein the laser unit and the modular optical barrel unit are optically coupled via optical fiber. The laser unit includes a laser source configured to generate a laser beam. The modular optical barrel unit includes an optically integrated configuration of an imaging unit, optical components, laser beam shaping equipment, and a laser beam focusing element. The laser beam generated by the laser unit is transmitted to the modular optical barrel unit via optical fiber. In such a configuration, the modular optical barrel is configured to perform various laser annealing and optical characterization functions, such as beam shaping of the laser beam (received from the laser unit) to generate a desired laser beam dot pattern for laser annealing, controlling the laser beam exposure time to control the annealing time, imaging for pattern image recognition to support computer vision inspection operations, laser beam and electrical probe alignment operations, etc.

[0040] In all exemplary embodiments of the laser annealing apparatus, the integration of the optical and electrical characterization devices enables the integration of laser tuning of a superconducting tunnel junction device (e.g., a Josephson junction) and in-situ electrical characterization of the superconducting tunnel junction device (e.g., measuring junction resistance measurements) to support laser tuning operations in a manner that increases the throughput of the laser tuning operation (e.g., tracking tuning progress over multiple laser annealing iterations). The integration of laser tuning and in-situ electrical characterization enables increased throughput and scalability of laser tuning processes (e.g., LASIQ processes for laser annealing of Josephson junctions of superconducting qubits to tune (e.g., adjust) the transition frequencies of superconducting qubits).

[0041] It should be understood that the various features shown in the accompanying drawings are schematic illustrations and not drawn to scale. Furthermore, the same or similar reference numerals are used throughout the drawings to denote the same or similar features, elements, or structures; therefore, detailed explanations of the same or similar features, elements, or structures will not be repeated for each drawing. Additionally, the term "exemplary" as used herein means "serving as an example, instance, or illustration." Any embodiment or design described herein as "exemplary" is not intended to be construed as superior to other embodiments or designs. Furthermore, the terms "about" or "substantially" used herein with respect to percentages, ranges, etc., mean approximately or approximate, but not exactly equal to. For example, the terms "about" or "substantially" as used herein mean that a small margin of error may exist, such as 1% or less than the stated amount.

[0042] It should also be understood that the phrase “configured to” used in conjunction with circuits, structures, elements, components, etc. that perform one or more functions or otherwise provide a certain function is intended to cover embodiments in which the circuits, structures, elements, components, etc. are implemented in hardware, software, and / or combinations thereof, and in implementations that include hardware, wherein the hardware may include discrete circuit elements (e.g., transistors, inverters, etc.), programmable elements (e.g., application-specific integrated circuit (ASIC) chips, field-programmable gate array (FPGA) chips, etc.), processing devices (e.g., central processing unit (CPU), graphics processing unit (GPU), etc.), one or more integrated circuits, and / or combinations thereof. Therefore, by way of example only, when circuits, structures, elements, components, etc. are defined as being configured to provide a particular function, they are intended to cover, but are not limited to, embodiments in which circuits, structures, elements, components, etc. consist of elements, processing devices, and / or integrated circuits that cause them to perform a particular function when in an operational state (e.g., connected or otherwise deployed in a system, powered on, receiving input, and / or generating output), as well as embodiments in a non-operational state (e.g., not connected and not otherwise deployed in a system, not powered on, not receiving input, and / or not generating output) or a partially operational state.

[0043] Furthermore, the term "quantum chip" as used herein is intended to broadly refer to any device that contains qubits and may also contain other quantum devices. For example, a quantum chip can be a semiconductor die containing an array (lattice) of qubits fabricated on a wafer containing multiple dies, and can be sliced ​​(diced) from the wafer using a die monolithization process to provide monolithized dies. In some cases, a quantum chip can be a wafer with multiple semiconductor dies. In the context of quantum computing, a quantum chip can contain one or more processors for a quantum computer.

[0044] Furthermore, as used herein, the term "shot" refers to a laser annealing operation performed by applying laser power to a target element (e.g., a Josephson junction) for a specified duration (annealing time). In the context of the exemplary embodiments of this disclosure discussed herein, a laser tuning method is provided to tune the junction resistance of a Josephson junction in a stepwise and incremental manner, wherein multiple "shots" are applied to a given Josephson junction to tune its junction resistance to a target junction resistance, in contrast to conventional methods that use only a single laser shot to tune a Josephson junction to a target junction resistance.

[0045] The term "iterate" or "iteratively" as used in this paper and in the context of the laser annealing process refers to a process involving a single "irradiation" and the associated control, measurement, and calculations performed by a LASIQ computer system and apparatus to determine the target annealing time and power for performing the annealing irradiation. Therefore, a laser annealing iteration or LASIQ iteration refers to the entire process of measuring the Josephson junction, determining the annealing power and time, and performing the annealing irradiation. In this sense, a single iteration involves the entire sequence of laser annealing systems and apparatuses because it is associated with a step in a stepwise approach to a resistance target of a Josephson junction. The tuning of a junction to completion (i.e., reaching its target resistance) can be described as an "iterative" progression. The term "iterative process" as used in this paper generally refers to a set of iterations, as applicable to one or more qubits or the like containing a Josephson junction, thereby tuning one or more qubits toward their respective targets.

[0046] The term "progressive" or "gradually" as used in this paper and in the context of the laser annealing process refers to a method of gradually adjusting the junction resistance of a Josephson junction toward its corresponding target resistance. This progressive method is the result of multiple annealing iterations, each involving laser irradiation to change the junction resistance toward the target resistance in a desired direction. Furthermore, this progressive method is asymptotic, meaning that the tuning rate nominally decreases as the junction resistance of a given Josephson junction gets closer to its corresponding target resistance.

[0047] The term "adaptive" or "adaptively" as used in this paper and in the context of the laser annealing process refers to the appropriate selection of laser annealing parameters (including parameters such as laser annealing time and annealing power) for laser irradiation to allow the Josephson junction resistances to monotonically and asymptotically approach their respective resistance targets. The adaptive nature of the laser annealing iteration is achieved using the method described in this paper, where the laser annealing time and power are selected based on a historical reconstruction of the tuning progress of a particular junction. The method described in this paper considers the historical tuning rate of the particular junction being tuned, thereby mitigating the risk of missing the resistance target (e.g., by using laser irradiation with excessive time, causing the junction resistance to be tuned beyond the desired resistance target).

[0048] The term "round-robin," as used herein and in the context of the laser annealing process for tuning Josephson junctions of qubits, refers to a tuning process in which, for example, the Josephson junctions of all qubits in a multi-qubit device undergo laser annealing sequentially, followed by another round-robin or multiple consecutive round-robins. Such round-robins can be performed continuously until all qubits in the multi-qubit device reach their respective targets. For example, a monolithic quantum chip may contain a number of qubit devices (e.g., 100 qubits, denoted as Q1, Q2, Q3, ..., Q100) that contain Josephson junctions. In an exemplary embodiment of the tuning method, Q1 is first tuned with one or more annealing iterations, as desired. The process proceeds to Q2, where one or more annealing iterations may be performed, as desired. Then the process proceeds to Q3, and so on, until finally Q100 is tuned with one or more annealing iterations, as desired. The entire process from Q1 to Q100 is defined as one round-robin. After the first successive iteration, the process can return to Q1 and repeat again until Q100 is reached. This continuous successive iteration process provides a means of time control and delay between iterations or groups of iterations, allowing the Josephson junctions to relax to their final junction resistance before the next annealing iteration or group of iterations.

[0049] Figure 1 A laser annealing system 100 for tuning a Josephson junction according to an exemplary embodiment of the present disclosure is schematically illustrated. In some embodiments, the laser annealing system 100 is configured to implement a LASIQ (Laser Annealing of Randomly Damaged Quantum Bits) tuning method for laser annealing of a Josephson junction for qubits after fabrication, in order to adjust and stabilize the junction resistance R. J This allows for the selective tuning of individual qubit frequencies through laser thermal annealing of the corresponding Josephson junction. For example... Figure 1As illustrated, the laser annealing system 100 includes a control system 110, a laser unit 120, an optical fiber 125, a microscope unit 130, a probe unit 140, and an optional environmental chamber 150.

[0050] The control system 110 includes a laser annealing control unit 111, an imaging control unit 112, a probe control unit 113, a data processing system 114, and a tuning and calibration data database 115. The laser unit 120 includes a laser source 121, an isolator 122, a laser power control block 123, and an optical fiber coupler 124. The microscope unit 130 includes a light source 131, a camera 132, a laser beam shutter 133, an optical fiber collimator 134, a laser beam shaper 135, multiple optical components 136, and an objective lens 137. The probe unit 140 includes an XYZ stage 142 and an electrical probe 144. A quantum chip 160 (or any other similar device under test) can be mounted on the XYZ stage. In some embodiments, the quantum chip includes a superconducting quantum bit lattice, wherein each superconducting quantum bit includes at least one corresponding Josephson junction, which can be annealed using a laser annealing system 100 to tune the junction resistance, thereby tuning the transition frequency of the superconducting quantum bit post-fabrication.

[0051] In some embodiments, the laser unit 120 and the microscope unit 130 include modular units coupled to each other via an optical fiber 125. In some embodiments, the optical fiber 125 includes a single-mode (SM) polarization-maintaining (PM) fiber configured to maintain the linear polarization of linearly polarized light injected into the optical fiber 125 by the laser unit 120 and propagating to the microscope unit 130. The microscope unit 130 includes a modular optical unit containing visible light and laser optical components. The microscope unit 130 may be integrated onto a probe unit 140 (e.g., a wafer-level probe). In this regard, in some embodiments, the laser unit 120, the microscope unit 130, and the probe unit 140 may be physically coupled / attached to each other to form an integrated laser annealing device configured to perform laser annealing operations for tuning the junction resistance of a Josephson junction and to perform in-situ junction resistance measurements under the control of a control system 110. In some embodiments, the control system 110 is operatively / communically coupled to the laser unit 120, the microscope unit 130, and the probe unit 140 via wired and / or wireless means. The control system 110 includes hardware and / or software for automatically controlling the various operations of the laser unit 120, microscope unit 130, and probe unit 140 of the laser annealing system 100.

[0052] Laser unit 120 is configured to generate a laser beam used by microscope unit 130 to generate a laser beam pattern comprising a single-point or multi-point beam pattern for laser annealing a given Josephson junction. In some embodiments, laser source 121 includes solid-state diode pumping to generate laser energy and includes a laser head to generate a focused laser beam from the laser energy emitted by the solid-state diode pumping. In some embodiments, the diode pumping includes a 532 nm (frequency doubling) diode-pumped solid-state laser (e.g., a second harmonic generation (SHG) laser). In some embodiments, the power level of laser source 121 (e.g., solid-state diode pumping) can be adjusted by control system 110. For example, the power level of laser source 121 can be set to one of several different power level settings (e.g., low power, medium power, high power settings). Isolator 122 is configured to provide polarization cleaning and optical isolation to mitigate unwanted feedback to the laser head of laser source 121.

[0053] Laser power control block 123 is configured to actively control and calibrate the power of the focused laser beam. For example, in some embodiments, laser power control block 123 includes a half-wave plate and a polarization beam splitter (PBS) coupled to a dump. The half-wave plate is configured to change the polarization direction of the laser beam output from isolator 122. Laser power control block 123 also includes a power monitor comprising, for example, an optical wedge configured to direct some laser beam power toward a silicon photodiode. The silicon photodiode generates an electrical signal indicating the laser power level, and this signal is fed back to control system 110 (e.g., laser annealing control unit 111), which generates a control signal applied to laser power control block 123 to adjustably control the laser power for laser tuning of the Josephson junction as indicated. More specifically, in some embodiments, the power level of the laser beam can be coarsely adjusted by controlling the power output of laser source 121, while the power level can be finely adjusted by the operation of laser power control block 123.

[0054] For example, in some embodiments, the half-wave plate of the laser power control block 123 is configured to change the polarization direction of the laser beam output from the isolator 122, and the half-wave plate includes an adjustable rotation which can be electronically controlled by the laser annealing control unit 111 to adjust the total attenuation by rotating the polarization incident on the polarization beam splitter to a desired power level. In some embodiments, the polarization beam splitter of the laser power control block 123 includes an optical filter that allows light waves of a specific polarization associated with the laser beam to pass through the optical filter and blocks light waves of other polarizations, thereby generating a laser beam with well-defined polarization.

[0055] The polarized laser light generated by laser unit 120 is coupled to single-mode polarization-maintaining fiber 125 (e.g., a single-mode polarization-maintaining fiber) via fiber coupler 124 and propagates to microscope unit 130. In microscope unit 130, fiber collimator 134 (e.g., a collimating lens) is configured to convert the laser light output from fiber 125 into a free-space collimated beam. In some embodiments, microscope unit 130 includes a power monitor comprising, for example, a beam sampler (e.g., a beam splitter) and a photodiode to monitor the power of the collimated laser beam, thereby enabling precise exposure control downstream of the power control / adjustment mechanism provided by laser unit 120.

[0056] Furthermore, in the microscope unit 130, the laser beam shutter 133 includes an electronic shutter that operates under the control of, for example, the laser annealing control unit 111 of the control system 110, to control the duration of laser exposure when annealing a given Josephson junction. For example, when annealing a target Josephson junction, the laser beam shutter 133 can be opened for a given duration to allow the annealing laser beam to be projected onto the quantum chip 160 near the target Josephson junction, and then automatically closed after the given duration. In this respect, the laser power level and pulse duration (laser exposure) can be controlled to achieve a desired change (e.g., a reduction) in the resistance of the annealed Josephson junction.

[0057] Laser beam shaper 135 is configured to split a collimated laser beam (which passes through laser beam shutter 133) into two or more laser beams having slightly different angles relative to each other. In some embodiments, laser beam shaper 135 includes diffractive optical elements (DOEs), such as a diffractive beam splitter, which splits a single laser beam into multiple beams (diffraction orders) in a predetermined configuration. The diffractive beam splitter includes holographic optical elements that impart a precise angle (e.g., 0.5 degrees offset) to the incident laser beam in a positive or negative angular direction relative to a reference plane, thereby generating multiple outgoing laser beams.

[0058] The number of laser beams generated by the laser beam shaper 135 can vary depending on the given application. For example, in some embodiments, the laser beam shaper 135 includes a 2×2 diffraction beam splitter that divides a single collimated laser beam into four separate laser beams, resulting in a final four-point illumination pattern that is projected onto a target location on the surface of the quantum chip 160, as will be discussed below. Figure 7DExemplary embodiments thereof are discussed. In some embodiments, the laser beam shaper 135 can be switched manually or automatically with different diffraction beam splitters (e.g., multiple DOEs on a rotary stage) to obtain different desired laser spot patterns. In this regard, different diffraction beam splitters can be selected to generate any desired number (e.g., 2, 3, 5, 6, etc.) of laser beams with defined illumination patterns tailored to different applications.

[0059] Microscope unit 130 implements light source 131 and camera 132 for illuminating and observing target features (e.g., qubits and corresponding Josephson junctions) on the surface of quantum chip 160 within a given field of view (FOV) of microscope unit 130. In some embodiments, light source 131 includes any suitable light generating device, including one or more light-emitting diodes (LEDs), monochromatic light sources, etc., having the desired photon wavelength. Light source 131, together with some optical components 136 in the optical observation path, implements Kohler illumination to create uniform illumination of the target features within the FOV of microscope unit 130 and ensures that the image of light source 131 is not visible in the resulting image captured by camera 132.

[0060] In some embodiments, camera 132 includes a charge-coupled device (CCD) image sensor or an infrared (IR) complementary metal-oxide-semiconductor (CMOS) image sensor. Camera 132 is used to capture images of target regions on the surface of quantum chip 160 to facilitate, for example, aligning electrical probe 144 with contact electrodes when performing in-situ Josephson junction resistance measurements, aligning laser beam patterns with target regions when performing laser annealing operations, etc. For example, in some embodiments, pattern recognition of, for example, an image of a Josephson junction template is used to align the Josephson junction of a given qubit with the center of the field of view (FOV) of microscope unit 130. Additionally, in some embodiments, more than one camera can be used in parallel by using a beam splitter to segment the image path and using, for example, an IR CMOS camera and a visible wavelength camera, which can be used for process monitoring (e.g., for inspection, process tracking, etc., with a wide FOV).

[0061] Optical assembly 136 includes various types of optical components for guiding, reflecting, focusing, modifying, and shaping optical signals (e.g., laser beams for annealing and visible / IR light for observation) as needed for a given application. For example, optical assembly 136 includes components such as mirrors, beam splitters, filters, polarizers, and various lenses (e.g., tube lenses, objectives, relay lenses, etc.). Objective lens 137 is the lens located closest to the device under test (quantum chip 160) and is used to provide a basic magnification for generating a magnified image observed by camera 132, and to project an annealed laser beam pattern (e.g., a four-dot pattern) onto the surface of quantum chip 160. In some embodiments, objective lens 137 includes a long working distance (WD) objective. In an exemplary, non-limiting embodiment, objective lens 137 (together with an optional second objective lens) is configured to compress the laser beam and multi-dot pattern by 4x while providing an image magnification of 20x.

[0062] Probe unit 140 is configured to automatically move the position of quantum chip 160 during the laser annealing process to align the target Josephson junction of a given qubit within the field of view (FOV) of microscope unit 130, in order to perform in-situ Josephson junction resistance measurements and laser annealing of the target Josephson junction. Specifically, quantum chip 160 is mounted to an automated XYZ stage 142, which is controllably movable in three dimensions to align the features of quantum chip 160 within the FOV of microscope unit 130 and enable contact between electrical probe 144 and contact pads on quantum chip 160. For example, in some embodiments, during the laser annealing process, an automated pattern recognition process is used to align the target Josephson junction of a given qubit with the center of the FOV of microscope unit 130, in which features of an image captured by camera 132 are automatically aligned with corresponding features of a template image to ensure correct positioning of the target Josephson junction and associated contact pads. Specifically, an alignment process is performed to ensure precise registration between the contact pads of the target Josephson junction and the electrical probe 144 during in-situ Josephson junction resistance measurement. Additionally, an alignment process is performed to ensure proper alignment between the target Josephson junction and the laser dot pattern during laser annealing.

[0063] As described above, the electrical probe 144 is implemented to perform in-situ Josephson junction resistance measurements during the laser annealing process. Specifically, in-situ Josephson junction resistance measurements are performed between laser annealing operations (irradiation) to track the tuning progress of the qubit's Josephson junction during a multi-step (i.e., iterative) annealing process in which the Josephson junction is progressively tuned. In some embodiments, the electrical probe 144 includes two pairs of probes configured to perform four-wire resistance measurements (or Kelvin resistance measurements) to more accurately measure the junction resistance of the Josephson junction. Typically, four-wire (Kelvin) resistance measurements involve determining the resistance of a given Josephson junction by measuring the current (I) flowing through the junction and the voltage drop (V) across the junction, and determining the junction resistance R according to Ohm's law. J That is, R J =V / I.

[0064] In some embodiments, the electrical probe 144 includes a probe card mechanically mounted to a fixed position on the probe unit 140. In some embodiments, the integration of the microscope unit 130 and the probe unit 140 is configured to ensure that the sample imaging plane and the laser focal plane are substantially identical, while the probe plane is offset from the sample imaging plane by a predetermined amount, such as 70 micrometers, 80 micrometers, etc. In this configuration, the electrical probe 144 is fixedly offset from the image plane, and the Z position of the XYZ stage 142 (on which the quantum chip 160 is mounted) moves to a default contact position to establish an electrical contact between the electrical probe 144 and the target contact pad on the quantum chip 160 to perform in-situ Josephson junction resistance measurements. In some embodiments, the microscope unit 130 may also be mounted on its own XYZ stage and may additionally move with corresponding X, Y, and Z degrees of freedom.

[0065] In some embodiments, the XYZ stage is positioned in various locations to enable imaging, electrical characterization, and annealing of the Josephson junction, allowing these functions to be performed safely and efficiently. The terms “contact position,” “annealing position,” and “safe position” are used herein to refer to these various positions of the XYZ stage.

[0066] As used herein, the term "contact position," within the context of the laser annealing system 100, refers to the location on the XYZ stage 142 where the sample (i.e., the quantum chip 160) and the probe are in mechanical and electrical contact. That is, the surface of the sample is substantially the same as the probe plane. In this "contact position" configuration, electrical characterization can occur, which typically involves four-wire (Kelvin) resistance measurements. Each annealing iteration typically involves a junction resistance measurement, where the XYZ stage 142 is brought into the "contact position" prior to subsequent annealing.

[0067] As used herein, the term "annealing position," in the context of the laser annealing system 100, refers to the Z position of the XYZ stage 142 such that the surface of the sample (i.e., the quantum chip 160) is located in the focal plane of the laser annealing beam. In an exemplary embodiment, in the "annealing position," the surface of the sample (i.e., the quantum chip 160) is substantially the same as the imaging plane, such that imaging and annealing both occur at the same Z position of the XYZ stage 142, or equivalently, the sample and the laser beam can be simultaneously focused and observed by the imaging system. Additionally, in the "annealing position," pattern recognition and alignment correction can occur, ensuring that the junction is correctly centered in the field of view (FOV) prior to annealing. Also in the annealing position, visual characterization, inspection, etc., can be performed to determine whether the chip is physically suitable for use as a chip candidate. Nominally, the "annealing position" can be selected to have a fixed difference from the "contact position," defined herein as the "separation distance," which can be, for example, 70 micrometers, 80 micrometers, etc., and can be selected by the operator as needed.

[0068] As used herein, the term "safe position," in the context of the laser annealing system 100, refers to a large offset of the Z position of the XYZ stage 142 such that the surface of the sample (i.e., the quantum chip 160) is safely offset from the "contact position," such that the highest surface feature of the sample does not cross the probe plane, or equivalently, no feature on the sample intersects the probe plane. In this way, regardless of whether the X or Y position is selected on the sample, when the XYZ stage 142 is in the "safe position," the probe is not at risk of damage due to collision with any surface feature.

[0069] In an exemplary embodiment, the probe card is fixed at the Z position, and the "separation distance" is selected to be 70 micrometers, i.e., the "annealing position" is 70 micrometers lower than the "contact position." Additionally, the "safe position" can be selected (e.g.) 1000 micrometers or greater, or a sufficiently large value greater than the height of any feature on the sample. When the device is initialized, the relative positions of the sample plane, probe plane, imaging plane, and laser annealing plane are not known a priori, and any operation performed using the laser annealing system 100 may exhibit, for example, image defocusing, poor electrical contact during probing, and / or poor annealing performance. Therefore, an initialization protocol must be executed to ensure that the contact position, annealing position, and safe position are well defined. In an exemplary embodiment, to define these positions, the XYZ stage 142 can be programmed to move to a safe position on a test chip, initialization chip, or the like, where a clean conductive surface (e.g., contact pads) is available below the probe. In this exemplary embodiment, a dedicated initialization chip with an array of conductive contact pads can be used to safely contact the electrical probe 144. Subsequently, the XYZ stage 142 increments toward the electrical probe 144 at the Z position (e.g., in 2-micrometer increments), checking the contact resistance for each increment until a contact threshold (e.g., 100 ohms, or another desired threshold) is reached. This indicates successful contact between the sample and the probe plane, or equivalently, that the sample plane and the probe plane are co-located, and the XYZ stage 142 is in the "contact position." After determining the contact position, the XYZ stage 142 decreases the desired 70-micrometer "separation distance" at the Z position, bringing the XYZ stage 142 to the "alignment position." However, it is possible that the image focal plane is not yet in a substantially identical position to the sample surface. In this case, the microscope unit can be adjusted manually using Z-focus adjustment or automatically (when the microscope is mounted on its own XYZ stage and controlled by the imaging control unit 112) so that the imaging focal plane becomes substantially identical to the sample plane. Using this protocol, the "annealing position" thus corresponds to the sample surface being focused in the microscope unit 130, and imaging and annealing can now occur at the "annealing position." In the case of desired electrical measurements, reliable detection can be achieved by simply incrementing the Z position of the XYZ stage 142 by 70 micrometers (i.e., the “separation distance”) or more, as some degree of overshoot is desirable for robust electrical contact. Furthermore, a “safe position” can be defined such that when moving between qubits or other features on the quantum chip 160, the XYZ stage 142 first moves to its safe position, then to the X and Y positions of the desired feature, then to an “annealing position” for imaging / tuning, or to a “contact position” for electrical characterization.The aforementioned initialization protocol can be generally implemented to ensure that bench movement, imaging, annealing, and electrical measurements can be performed safely and reliably. It should be understood that, in one or more embodiments, the aforementioned initialization protocol, along with various XYZ bench 142 positions, is actively used in the operation and calibration of the laser annealing system 100. In some embodiments, the laser focal plane can be designed to have additional degrees of freedom relative to the image focal plane and can focus or defocus the laser beam as needed.

[0070] In some embodiments, the probe unit 140 is housed or otherwise disposed within an optional ambient chamber 150 to control the surrounding environment during laser annealing, wherein different ambient environments affect the progress of laser annealing in different ways. For example, in some embodiments, the laser annealing system 100 may include an ambient gas control system coupled to the ambient chamber 150 and configured to inject a mixture of one or more gases into the ambient chamber 150 to control the annealing environment. More specifically, in some embodiments, the ambient gas control system may include a gas dilution unit connected to multiple gas cylinders storing different gases (e.g., nitrogen, dry air, etc.), wherein the gas dilution unit may mix different gases at various concentrations as needed and may inject the mixed gas into the ambient chamber 150 to provide a given gaseous environment for laser annealing. Additionally, the ambient gas control system includes a vacuum system coupled to the ambient chamber 150 to evacuate annealing gases from the chamber or otherwise evacuate air from the ambient chamber 150 to perform laser annealing in a vacuum atmosphere.

[0071] Furthermore, in some embodiments, a temperature control system is coupled to the XYZ stage 142 (e.g., a wafer chuck) to control the temperature of the XYZ stage 142 on which the quantum chip 160 is mounted. The XYZ stage 142 can be temperature-controlled to allow high-temperature annealing (e.g., overall annealing) or low-temperature probing for low-noise resistance measurements, and to reduce the relative contribution of substrate conductivity to junction resistance measurements. For example, in some embodiments, the XYZ stage 142 can be temperature-controlled within a range of -60°C to 300°C.

[0072] As described above, the various functions of the laser unit 120, microscope unit 130, and probe unit 140 are automatically controlled by the control system 110. In some embodiments, the laser annealing control unit 111, imaging control unit 112, and probe control unit 113 include corresponding hardware interfaces for interfacing with the laser unit 120, microscope unit 130, and probe unit 140 as needed to generate and apply control signals to the components of these units 120, 130, and 140, and to receive and process signals (e.g., data, measurements, feedback control signals, etc.) received from the components of these units 120, 130, and 140. The data processing system 114 includes one or more processors that execute software programs / routines to control laser annealing, imaging, and probe operations (e.g., performing automated pattern recognition for active alignment, performing junction resistance measurement calculations, etc.) in a coordinated manner by processing data received from control units 111, 112, and 113 when performing laser annealing and in-situ junction resistance measurements, and to generate and output control signals to enable control units 111, 112, and 113 to control the operation of laser unit 120, microscope unit 130, and probe unit 140, as discussed herein.

[0073] For example, in some embodiments, the laser annealing control unit 111 is configured to control the operation of components of the laser unit 120, such as the laser source 121 and the laser power control block 123, to adjust the power level of the laser beam output from the laser unit 120. Additionally, the laser annealing control unit 111 is configured to control the operation of components of the microscope unit 130 for laser annealing operations. For example, the laser annealing control unit 111 is configured to control the operation of the laser beam shutter 133 to control the laser exposure duration when the laser is tuned to a given Josephson junction. Furthermore, in some embodiments, the laser annealing control unit 111 is configured to control the laser beam shaper 135 to, for example, switch the diffraction beam splitter settings and the corresponding laser illumination pattern.

[0074] Furthermore, in some embodiments, the imaging control unit 112 is configured to control the operation of the light source 131, the camera 132, and one or more optical components 136 (e.g., tube mirrors) that make up the image path of the microscope unit 130. For example, the imaging control unit 112 may generate camera control signals to cause the camera 132 to capture an image within the field of view (FOV) of the microscope unit 130 and send the image to the imaging control unit 112. The imaging control unit 112 may be configured to preprocess image data into a format suitable for processing by the data processing system 114 to perform automated pattern recognition functions, to perform laser alignment and electrical probe alignment operations, as discussed herein.

[0075] Furthermore, in some embodiments, the probe control unit 113 is configured to control the operation of the probe unit 140. For example, the probe control unit 113 includes hardware for generating a test voltage applied to the electrical probe for performing junction resistance measurements. For instance, for a 4-wire (Kelvin) resistance measurement, the probe control unit 113 may include current and voltage measurement circuitry coupled to the electrical probe 144 and configured to measure the current flowing through the Josephson junction due to the application of the test voltage to the electrical probe, and to measure the voltage across the Josephson junction. The measured current and voltage can be digitized and sent to the data processing system 114 for calculating the junction resistance. Additionally, the probe control unit 113 includes control elements for precisely controlling the movement and positioning of the XYZ stage 142.

[0076] In some embodiments, the data processing system 114 performs a calibration process by performing laser annealing on a Josephson junction of representative hardware using different combinations of laser annealing power and annealing time to generate tuning calibration data (stored in a tuning calibration data database 115). The tuning calibration data can be obtained by performing a calibration process on representative hardware, wherein in some embodiments, the representative hardware may be a virtual Josephson junction residing on the same quantum chip to be tuned, and in other embodiments, the representative hardware may be a Josephson junction of qubits formed on a symmetric chiplet from the same fabrication process. The tuning calibration data is analyzed using statistical methods to fit the tuning calibration data to a tuning curve, wherein the tuning curve is used to determine the tuning rate and maximum tuning range of the Josephson junction at different laser annealing powers and annealing times. The tuning curve is utilized by the data processing system 114 to select a desired target combination of annealing power and annealing time for the target tuning rate and maximum tuning range of a Josephson junction on a given quantum chip after fabrication. In some embodiments, the tuning profile is used to predict the initial laser annealing operation (initial irradiation) for tuning a given Josephson junction toward a specific target (e.g., to 50% of the target) during a first irradiation. The calibration process ensures smooth and rapid approach to the target tuning for a given Josephson junction while mitigating the risks of undertuning and overtuning.

[0077] In some exemplary embodiments, the control system 110 for the laser annealing system 100 may be implemented using any suitable computing system architecture configured to implement methods supporting the automated control processes described herein by executing computer-readable program instructions embodied on a computer program product, the computer program product including a computer-readable storage medium (or media) having such computer-readable program instructions thereon, such that a processor executes the control methods discussed herein. This will be combined with... Figure 10An exemplary architecture for implementing a computing environment configured to control an exemplary laser annealing device for tuning Josephson junctions, as disclosed herein, is discussed in further detail. It should be understood that... Figure 1 The exemplary laser annealing system 100 can be used to perform exemplary laser tuning methods, such as those for tuning the junction resistance of superconducting tunnel junction devices for various applications, for example, with... Figure 2C , Figure 5 , Figure 6 , Figure 7A , Figure 7B , Figure 7C , Figure 7D , Figure 8A , Figure 8B and Figure 9 In conjunction with the methods discussed in detail, such as the junction resistance of the Josephson junction used to tune superconducting qubits, the transition frequency can be tuned using LASIQ tuning operations based on the exemplary adaptive laser tuning techniques discussed herein.

[0078] It should be pointed out that, in Figure 1 In the exemplary laser annealing system 100, the laser unit 120 and the microscope unit 130 jointly include optical devices, and the probe unit 140 includes electrical characterization devices. The optical devices and electrical characterization devices include an integrated configuration of a laser annealing device configured to perform various operations in situ to facilitate laser tuning of the junction resistance of a superconducting tunnel junction device (e.g., a Josephson junction) on a quantum chip. Such operations include, for example, laser annealing operations for laser tuning of the junction resistance of the superconducting tunnel junction device on the quantum chip, and in-situ resistance measurements to measure the junction resistance of the superconducting tunnel junction device before, during, and / or after the laser annealing operations as needed, to determine or otherwise track the progress of junction resistance tuning of the superconducting tunnel junction device.

[0079] In some embodiments, the electrical characterization apparatus is configured to perform a direct current (DC) resistance measurement operation to measure the junction resistance of a superconducting tunnel junction device. In some embodiments, the electrical characterization apparatus is configured to perform an alternating current (AC) resistance measurement operation to measure the junction resistance of a superconducting tunnel junction device. In some embodiments, a four-wire (Kelvin) resistance measurement is used to perform the resistance measurement for more accurate measurement of the junction resistance. In some embodiments, the electrical characterization apparatus includes a wafer-level probe device (e.g., a 200 mm or 300 mm wafer-level probe device) configured to perform the integrated electrical characterization techniques discussed herein. The wafer probe includes at least one of automated and semi-automated wafer probing systems.

[0080] Furthermore, in some embodiments, as described above, the electrical characterization device (e.g., probe unit 140) includes an environmental chamber (e.g., chamber 150). Figure 1The environmental chamber is configured to control the surrounding environment of the quantum chip when performing a laser annealing operation. For example, the environmental chamber is configured to control the surrounding environment as needed during, for example, laser annealing operations, by (i) controlling the composition of one or more gases within the environmental chamber, and (ii) generating a vacuum within the environmental chamber. The following will combine... Figure 4 Exemplary techniques for controlling the surrounding environment are discussed in further detail.

[0081] Furthermore, in some embodiments, the electrical characterization device (e.g., probe unit 14) includes a thermal control system configured to (i) heat the quantum chip to perform an overall thermal annealing operation for adjusting the junction resistance of the superconducting tunnel junction device of the quantum chip, and (ii) cool the quantum chip to perform at least one of in-situ resistance measurements. The following will combine examples... Figure 4 , Figure 8A , Figure 8B and Figure 9 Exemplary devices and techniques for implementing and utilizing thermal control are discussed in further detail.

[0082] It is important to note that Figure 1 An exemplary laser annealing apparatus is illustrated, wherein the optical device is partially implemented using a modular optical barrel unit (e.g., microscope unit 130), which includes an optically integrated configuration of an imaging unit, optical components, laser beam shaping equipment, and a laser beam focusing element. Specifically, microscope unit 130 includes a modular optical barrel unit with integrated components configured to generate, align, and project a desired laser beam pattern onto the surface of a quantum chip to perform a laser annealing operation. Microscope unit 130 is "modular" because it provides an optical barrel unit that includes encapsulated functional components for performing various functions (e.g., imaging, laser beam pattern generation, and delivery), and provides portability for use with a suitable configuration of laser unit 120 and probe unit 140. Modular microscope unit 130 includes a compact and portable optical mirror assembly that can be mounted on a desired probe unit and can be coupled to any suitable laser unit via single-mode fiber 125 to receive laser beam energy from a separate laser unit. In this respect, the modular microscope unit 130 does not include an actual laser source, thus allowing it to be manufactured to be more compact and portable.

[0083] In this regard, at a basic level, the microscope unit 130 includes an optical microscope apparatus comprising an optically integrated configuration of components for performing functions such as, for example, imaging a target device within the field of view of the optical microscope apparatus, laser annealing the target device by generating a laser beam dot pattern from a laser beam received from a remote laser source via an optical fiber, and controlling the exposure duration of the laser beam dot pattern for laser annealing the target device. The optical microscope apparatus includes a modular device configured to be mounted to an electrical characterization system to enable in-situ electrical characterization of the target device in conjunction with laser annealing, wherein in some embodiments, the electrical characterization system includes a wafer-level probe unit.

[0084] Figure 2A A laser annealing apparatus including a modular optical barrel unit is schematically illustrated according to an exemplary embodiment of the present disclosure. Specifically, Figure 2A A laser annealing apparatus including a laser unit 210, an optical fiber 215, and a modular optical barrel unit 220 is schematically illustrated. In some embodiments, the modular optical barrel unit 220 is schematically shown for implementing... Figure 1 An exemplary architecture of the microscope unit 130 with a laser annealing device is shown. The modular optical tube unit 220 includes a light source 221, a camera 222, a fiber collimator 223, a laser beam shaper 224, a laser beam shutter 225, and an objective lens 226, which perform the same or similar functions as the corresponding components of the microscope unit 130 described above, and their details will not be repeated.

[0085] Furthermore, the modular optical tube unit 220 includes multiple optical components, such as lens 231, mirror 232, beam splitter 233, notch filter 234, relay lens 235, mirror 236, relay lens 237, beam splitter 238, and optional quarter-wave plate 239, which are collectively configured to guide, reflect, focus, modify, and shape optical signals (e.g., laser beams for annealing and visible / infrared light for viewing) as required by a given application. Typically, the tube 230 includes a multi-element optical assembly configured to focus parallel light passing through objective lens 226 onto the image plane of the focal plane array of camera 222. Notch filter 234 is configured to filter light using known techniques. Beam splitters 233 and 238 are optical components configured to split incident light into two separate beams at a specified ratio and combine the two distinct beams into a single beam. Relay lenses 235 and 237 are configured to relay the laser beam along the optical laser path from beam shaping element 224 to objective lens 226. An optional quarter-wave plate 239 can be used to change the polarization state of light passing through the plate. For example, the optional quarter-wave plate 239 can be implemented to convert linearly polarized light to circularly polarized light, and vice versa.

[0086] In the light source path, lens 231 is configured to "parallelize" the light emitted from light source 221 to form illumination beam 240. Illumination beam 240 is directed along the optical path by mirror 232 to beam splitter 233, passes through notch filter 234, beam splitter 238, optional quarter-wave plate 239, and is focused by objective lens 236 to illuminate a portion of quantum chip 260 within the field of view (FOV) of objective lens 226. Light source 221, together with optical components 231, 232, and 233, implements a Kohler illumination configuration to create uniform illumination of the target feature within the FOV of objective lens 226, while ensuring that the image of light source 221 is not visible in the resulting image captured by camera 222.

[0087] In the laser beam path, fiber collimator 223 collimates the laser emitted from fiber 215 to generate a collimated laser beam 250. In some embodiments, the modular optical barrel unit 220 includes a power monitor 240, which includes, for example, a beam sampler 241 (e.g., a beam splitter) and a photodiode 242, to monitor the power of the collimated laser beam 250, thereby enabling precise exposure control downstream of the power control / adjustment mechanism provided by the laser unit 210. The collimated laser beam 250 propagates to a laser beam shaper 224, which, as described above, is configured to split the collimated laser beam 250 into two or more laser beams having slightly different angles relative to each other. As described above, the laser beam shaper 224 includes diffractive optical elements, such as a diffractive beam splitter, which splits a single laser beam into a predetermined configuration of multiple beams (diffraction orders).

[0088] Figure 2B This is a perspective view of a modular optical lens barrel unit according to exemplary embodiments of the present disclosure. Specifically, Figure 2B An exemplary modular optical barrel unit 220-1 is shown, which is based on Figure 2A An exemplary integrated optical component architecture is schematically shown in the figure. Figure 2B The exemplary modular optical barrel unit 220-1 shown includes a portable, compact optical system that can be easily mounted on any suitable probe unit (e.g., a wafer-level probe system) to integrate the optical and electrical characterization functions of the laser annealing device to perform in-situ laser annealing and junction resistance measurement operations to facilitate laser tuning of superconducting tunnel junction devices on a quantum chip, for example, performing a LASIQ process to tune the transition frequencies of qubit devices in a given qubit lattice of the quantum chip 160.

[0089] Figure 2C A flowchart illustrating a method for performing laser tuning operation using a laser annealing apparatus including a modular optical barrel unit, according to exemplary embodiments of the present disclosure, is shown. In some embodiments,Figure 2C An exemplary embodiment of the present disclosure is shown, comprising a modular optical tube unit (e.g., a modular microscope unit 220). Figure 2A The laser annealing apparatus performs the operation to perform laser tuning. Figure 2C A high-level process 260 for performing laser tuning operations is illustrated. A laser beam is generated by the laser unit (box 261). The laser beam is transmitted to the modular microscope unit via an optical fiber optically coupled to the laser unit (box 262). The target device to be laser annealed (e.g., a Josephson junction of qubits) is aligned with the FOV of the modular microscope unit using an imager of the modular microscope unit (box 263). More specifically, in some embodiments, as explained in further detail below, the alignment process includes, for example, imaging the FOV via the imager of the modular microscope unit to generate a sample image of the FOV, performing a pattern recognition process (via a control system) by comparing the sample image with a template image to determine the offset between the sample image and the template image, and moving the target device on the XYZ stage based on the determined offset to align the target device within the FOV of the modular microscope unit. The modular microscope unit generates a laser beam pattern from the laser beam (provided by the laser unit) to laser anneal the target device with the laser beam pattern (box 264).

[0090] It should be noted that, although Figure 1 , Figure 2A and Figure 2B An exemplary embodiment of a laser annealing apparatus with an integrated configuration including a modular optical barrel and an electrical characterization device is shown. However, in other embodiments, a laser annealing apparatus may be implemented using discrete benchtop optics combined with electrical characterization devices to perform laser tuning operations and related operations as described herein. For example, Figure 3A A laser annealing system according to another exemplary embodiment of the present disclosure is schematically illustrated. In particular, Figure 3A A laser annealing system 300 is schematically shown, which includes a control system 310, an imaging unit 320, a laser unit 330, and a probe unit 140 (e.g., an electrical characterization device). Figure 3A An exemplary embodiment of an integrated configuration of discrete tabletop optical devices (e.g., implemented by imaging unit 320 and laser unit 330) and electrical characterization devices (e.g., implemented by probe unit 140) is shown to perform the laser annealing operation discussed herein.

[0091] Laser unit 330 includes a laser source to generate a laser beam, and various laser optical components that operate together to generate a laser beam pattern from the laser beam generated by the laser source, project the laser beam pattern onto a target sample to perform laser annealing, and control the annealing time using an electronic shutter, etc. Imaging unit 320 is a separate unit optically coupled to laser unit 320. Imaging unit 320 is configured to support various operations such as real-time visualization, imaging, pattern recognition, and other related functions discussed herein. Control system 310 is configured with suitable hardware and software to use with... Figure 1 The control system 110 uses the same or similar control and data processing functions to control the operation of the imaging unit 320 and the laser unit 330, and its details will not be repeated. The imaging unit 320 and the laser unit 320 can be implemented using any suitable architecture, such as... Figure 3B As shown.

[0092] Figure 3B The illustration schematically shows an exemplary embodiment of the present disclosure that can be implemented... Figure 3A The optical system implemented in the laser annealing system. Specifically, Figure 3B An imaging unit 320, a laser unit 330, and an XYZ stage 142-1 for mounting a quantum chip 160 to be laser-annealed are schematically shown. Typically, the imaging unit 320 includes a camera 321, a tube mirror 322, and a beam splitter 232. The laser unit 330 includes a laser source 331 comprising a laser head 332 and a diode pump 333 to generate laser energy, wherein the diode pump 333 is cooled using any suitable thermoelectric cooling device. The laser unit 330 also includes an isolator 334, a laser power monitoring and control block 335 (which includes a half-wave plate 336, a polarizing beam splitter 337, a collector 338, an optical wedge mirror 339, and a photodiode 340), an electronic shutter 341, a piezoelectric mirror mount 342, a beam reducer 343, a diffraction grating 344 (for generating a laser beam pattern), a focusing lens 345, a first objective lens 346 and a second objective lens (providing a dual-objective system), and a polarizing beam splitter 348. Imaging unit 320 and laser unit 330 are optically coupled via beam splitter 323 and polarization beam splitter 348.

[0093] Various components of the imaging unit 320 and the laser unit 330 are combined with the above. Figure 1The same or similar methods are discussed. For brevity, in some embodiments, the laser source 33 includes a 532nm (frequency-doubled) diode-pumped solid-state laser to generate a laser beam used as a laser annealing source. A laser power monitoring and control block 335 actively calibrates the laser beam power via a combination of a half-wave plate 336 and a polarization beam splitter 337. An optical window wedge mirror 339 serves as a laser power pickup to a silicon photodiode 340 to monitor the laser power level and set an appropriate laser power level for laser annealing operation. A piezoelectric mirror mount 342 actively aligns the laser beam within the FOV of the objective (via image pattern recognition), and the laser beam is optionally shaped by a diffraction grating 344 (e.g., a holographic diffraction grating) to create a multi-point beam pattern. The beam size is compressed by 4x using a dual-objective setup, which also provides 20x junction image magnification. A magnified image of the quantum chip 160 is imaged by a camera 321 and used for active alignment of a target device (e.g., a Josephson junction of a qubit).

[0094] Figure 4 A laser annealing system according to another exemplary embodiment of the present disclosure is schematically illustrated. In particular, Figure 4 A laser annealing system 400 is schematically shown, comprising an optical system 410, a probe control unit 420, an electrical characterization system 440 (e.g., a probe unit) disposed in an environmental chamber 450, an environmental control unit 430, and an ambient environment system 460. The optical system 410 includes a laser system, an imaging system, and associated optical components. The optical system 410 can utilize the aforementioned combination... Figure 1 , Figure 2A , Figure 2B , Figure 3A and Figure 3B Implemented by any of the exemplary optical architectures of the discussed laser unit, imaging unit, and modular microscope unit.

[0095] The electrical characterization system 440 (e.g., a probe unit) includes an XYZ stage 442 with a wafer chuck and an electrical probe 444, the wafer chuck including a thermoelectric cooler 443. The configuration and operation of the electrical characterization system are in conjunction with the above description. Figure 1Similar to the probe unit 140 discussed, the exemplary electrical characterization system 440 implements a thermoelectric cooler 443 to provide a thermal control system (e.g., a temperature-controlled wafer chuck system or other suitable heating / cooling system) configured to (i) heat the quantum chip 160 to perform a global thermal annealing operation to adjust the junction resistance of the tunnel junction device of the quantum chip 160, and (ii) cool the quantum chip 160 to perform in-situ resistance measurements, as will be discussed in further detail below. In some embodiments, the temperature-controlled wafer chuck system may be temperature-controlled in the range of -60°C to 300°C. The probe control unit 420 includes or otherwise implements an automated test equipment (ATE) system 422, which includes a combination of hardware and software to control the automated operation of the electrical characterization system 400 (e.g., automated movement of probes, generation of test signals, processing of voltage / current signals generated as a result of resistance measurement probe operations, etc.).

[0096] An electrical characterization system 440 is housed within or otherwise arranged within an environmental chamber 450 to control the surrounding environment within the environmental chamber 450 via the operation of an environmental control unit 430 and an ambient environment system 460. The ambient environment system 460 includes a gas mixing and dilution system 470, which includes an ambient gas control system coupled to the environmental chamber 450 and configured to inject a mixture of one or more gases into the environmental chamber 450 to control the annealing environment. The gas mixing and dilution system 470 is connected to a plurality of gas cylinders 472-1, ..., 472-n, which store different gases (e.g., nitrogen, dry air, etc.). The gas mixing and dilution system 470 operates under the control of the environmental control unit 430 to mix different gases at various concentrations and inject the mixed gas into the environmental chamber 450 as needed to provide a given gaseous environment for laser annealing. Furthermore, the environmental system 460 includes a vacuum system 480 coupled to the environmental chamber 450 to evacuate the annealing gas from the chamber 450, or otherwise evacuate air from the environmental chamber 450, thereby performing laser annealing in a vacuum atmosphere. An exhaust system 482 is coupled to the vacuum system 480, wherein the exhaust system is configured to guide the evacuated gas for appropriate disposal.

[0097] Figure 5 A flowchart illustrating a method for tuning a Josephson junction of a qubit device based on a tuning scheme according to exemplary embodiments of the present disclosure is shown. Specifically, Figure 5Process 500 is illustrated, which includes various operations that can be performed using exemplary laser annealing systems and apparatuses as disclosed herein to perform in-situ junction resistance measurements and laser annealing operations on the Josephson junction of a superconducting qubit based on a frequency tuning scheme generated and updated to eliminate or otherwise minimize the probability of frequency collisions in a given qubit lattice, to tune the junction resistance of the Josephson junction to a corresponding target junction resistance, thereby tuning the transition frequency of the superconducting qubit of the given qubit lattice (via a LASIQ tuning process).

[0098] refer to Figure 5 Process 500 includes an initial step (block 501) of placing a quantum device (e.g., a quantum chip or quantum wafer) on an XYZ stage of an electrical characterization system (e.g., a probe unit) and optically inspecting the quantum device using an optical system (e.g., a modular microscope unit) to check for physical defects or damage. In an exemplary embodiment, the quantum device includes a lattice of superconducting qubits to be laser-tuned post-fabrication to adjust the transition frequencies of the superconducting qubits according to an initial frequency tuning scheme generated for the lattice of the superconducting qubits. If the optical inspection is deemed acceptable (affirmative judgment in block 502), process 500 continues to obtain the initially generated frequency tuning scheme, assuming that the frequency tuning scheme is now acceptable (affirmative judgment in block 503).

[0099] Process 500 continues to perform a laser annealing operation on the Josephson junction of the superconducting qubit to adjust the junction resistance of the corresponding Josephson junction to the corresponding target junction resistance (box 504). The target junction resistance (R0) of the given Josephson junction of the superconducting qubit is specified in the tuning scheme. target ), where the target junction resistance of a given Josephson junction corresponds to the target transition frequency of the associated superconducting qubit. As the junction resistance of the Josephson junction is progressively adjusted toward their respective target junction resistance by performing iterative annealing operations, process 500 performs in-situ resistance measurements between laser annealing operations to determine the current junction resistance of the Josephson junction (box 505).

[0100] After one or more iterations of the laser annealing process, it is determined whether laser tuning is complete (box 506). If in-situ resistance measurements indicate that some or all of the Josephson junctions are not at their respective target junction resistances, the laser tuning process is considered incomplete (negative judgment in box 506). In some embodiments, a yield assessment (box 506) is performed to determine, for example, how many frequency collisions are expected based on the current junction resistance of the Josephson junctions (and therefore the current transition frequencies of the corresponding superconducting qubits) for a given frequency tuning scheme. Based on the results of the yield assessment, if the current tuning scheme is determined to be unacceptable (negative judgment in box 503), a new, updated tuning scheme is generated (box 509). For example, if the yield assessment indicates that at least some of the target transition frequencies specified in the current tuning scheme cannot be achieved, based at least in part on the currently measured junction resistance of the Josephson junctions, the current tuning scheme may be considered unacceptable. The laser tuning operation then continues based on the new, updated tuning scheme (returning to box 504). When the laser tuning process is considered complete (positive judgment in box 506), process 500 can continue to perform post-laser tuning analysis (box 507).

[0101] In some embodiments, exemplary laser tuning methods as discussed herein include iterative laser tuning methods for tuning the junction resistance of a superconducting tunnel junction device (e.g., a Josephson junction) by implementing an asymptotic tuning method, wherein, for example, the Josephson junction of a qubit in a given multi-qubit device is adaptively and incrementally tuned to gradually adjust the junction resistance toward a corresponding target junction resistance of the Josephson junction. In some embodiments, as described below... Figure 6 To explain further in detail, adaptive and incremental tuning of a given Josephson junction is achieved by adaptively determining the annealing time for a given tuning iteration at a given laser power level. This annealing time is determined as a function of (i) the amount of resistance adjustment remaining to reach the target junction resistance and (ii) the total annealing time previously spent on laser annealing iterations applied to the superconducting tunnel junction. This iterative tuning method contrasts with conventional tuning methods, where a single laser irradiation or a single annealing iteration is used to tune the Josephson junction to the target junction resistance, which is unpredictable.

[0102] Furthermore, in some embodiments, the exemplary laser tuning method is configured to determine a target combination of laser power level and annealing time for a given Josephson junction to perform an initial laser annealing operation (initial irradiation) on the given Josephson junction to achieve initial junction resistance adjustment that reaches an initial target resistance. ), which corresponds to, for example, the specified target junction resistance. Approximately 50% resistance adjustment. Specifically, the initial irradiation is configured to achieve initial resistance adjustment. ,in ,in In an exemplary embodiment, for a given Josephson junction, an initial laser annealing operation (initial irradiation) is performed under a determined combination of laser power level and annealing time to achieve approximately 50% [efficiency / achievement]. Or, depending on any other expected percentage of the application.

[0103] In some embodiments, as described above, tuning calibration data 115 ( Figure 1 The calibration data 115 is used to determine a target combination of laser power level and laser annealing time to be used for initial irradiation of a given Josephson junction. The calibration data 115 includes information such as, for example, the maximum achievable tuning range for each of a plurality of different combinations of laser power and annealing time, and tuning profiles representing the tuning rates of the different combinations of laser power and annealing time. In some embodiments, calibration data is obtained by performing a calibration process that typically includes (i) performing laser annealing operations on a set of test Josephson junctions using different combinations of laser power and annealing time, (ii) determining the junction resistance adjustment of the test Josephson junctions as a result of the laser annealing operations, and (iii) using the determined junction resistance adjustment of the test Josephson junctions to determine calibration data for configuring the laser annealing operation for laser tuning of the Josephson junctions corresponding to the test Josephson junctions. In some embodiments, a set of test Josephson junctions resides on a test quantum chip (e.g., a sister chiplet) having test Josephson junctions, wherein the test Josephson junctions are manufactured using the same manufacturing process used to manufacture Josephson junctions to be laser-tuned by the laser annealing operation configured using the calibration data. In other embodiments, a set of test Josephson junctions resides on the same quantum chip (e.g., in the cut-track region) as the Josephson junctions to be laser-tuned by laser annealing configured using calibration data.

[0104] Figure 6 A flowchart illustrating a method for tuning a Josephson junction according to an exemplary embodiment of the present disclosure is shown. In some embodiments, Figure 6 The control process for iteratively and adaptively tuning the Josephson junction of qubits on a quantum chip is illustrated, which can be performed using any of the exemplary laser annealing systems discussed herein (e.g., Figure 1 The laser annealing system 100). Figure 6 An exemplary embodiment of an iterative tuning process in a sequential loop format is shown, wherein each sequential loop involves traversing all Josephson junctions, each Josephson junction being measured and “illuminated” once to achieve incremental junction resistance adjustment, such that each successive iteration is performed on a different Josephson junction on the quantum chip. Figure 6An exemplary embodiment of the tuning process is also shown, wherein a probe contact resistance check and a probe contact stability check are performed before each in-situ junction resistance measurement to ensure sufficient contact between the electrical probe and the contact pads of the Josephson junction being tested.

[0105] refer to Figure 6 The quantum chip is placed on the XYZ stage 142 of the probe unit 140, and the control system 110 initiates an autotuning process (box 600). The autotuning process selects the initial Josephson junction of the qubit and moves to the selected Josephson junction (box 601). Specifically, the control system 110 moves the XYZ stage 142 to place the initial Josephson junction into the field of view of the microscope unit 130. The tuning process initiates control operations to cause the microscope unit and the probe unit to perform focusing and alignment processes to ensure proper focusing to the focal plane and correct alignment of the target Josephson junction within the field of view of the microscope unit 130 for the purpose of performing in-situ Josephson junction resistance measurements (box 602). The following will be combined with... Figure 7A An exemplary focusing process is described. Focusing ensures that the sample plane (e.g., the plane containing the target Josephson junction) is located at the focal plane (i.e., the focal plane) of objective lens 137. Focusing can be adjusted by adjusting the Z position of XYZ stage 142. As described above, alignment to the Josephson junction is performed using a machine learning pattern recognition process to align the Josephson junction to the center of the field of view. Additionally, depending on a given iteration, the alignment can be slightly adjusted at the X and / or Y positions to ensure that the electrical probes of the probe unit fall at different locations on the contact pads of the Josephson junction, rather than at the same locations on each tuning iteration of the Josephson junction.

[0106] Next, the tuning process continues, causing the probe unit to move the contact pads of the Josephson junction to contact the electrical probes and perform contact resistance and contact stability checks (box 603). The following will combine... Figure 7B An exemplary procedure for checking contact resistance and contact stability is described. After successfully completing the contact resistance and contact stability tests, an in-situ junction resistance measurement is performed using the same or similar resistance measurement method discussed herein (e.g., Kelvin resistance measurement) to determine the current junction resistance of the Josephson junction (box 604).

[0107] The tuning process determines the measured junction resistance of a given Josephson junction. Is it at or near the target junction resistance of a given Josephson junction? (Box 605). For example, as described above, determine the currently measured junction resistance. Is it at the target junction resistance? Within the specified threshold percentage, that is, (For example If the measured junction resistance of a given Josephson junction is determined... The target junction resistance is not at (or close to) that of a given Josephson junction. If the negative judgment in box 605 is true, then the tuning process is ready to perform laser annealing.

[0108] For example, the tuning process initiates a control operation to cause the microscope unit 130 and probe unit 140 to perform focusing and alignment processes, so as to ensure proper focusing to the focal plane and correct alignment of the target Josephson junction within the field of view of the microscope unit 130 for the purpose of performing laser annealing (box 606). The following will be combined with... Figure 7C An exemplary focusing and alignment process for preparing for laser annealing operations is discussed in further detail. Additionally, the tuning process continues, determining, for a given iteration, the “irradiation” annealing time and laser power to be used for laser annealing of a given Josephson junction based on the measured junction resistance (box 607). Using the above in conjunction with Figure 2, Figure 3A and Figure 3B The same or similar methods discussed will be used to perform the process, and there is no need to repeat the details.

[0109] A given iteration of laser annealing (irradiation) is performed using the determined annealing time and laser power to laser anneal the given Josephson junction (box 608). After the final annealing operation is completed, the tuning process proceeds to the next Josephson junction to be tuned (box 601) and repeats the process. The tuning process terminates (box 610) when it is determined at a given point in the iteration process that the currently selected Josephson junction is at its corresponding target resistance (positive judgment in box 605) and there are no remaining Josephson junctions to be further tuned (negative judgment in box 609). In this case, it is assumed that each Josephson junction is tuned to its corresponding target junction resistance, and therefore, each corresponding qubit is tuned to its corresponding target transition frequency.

[0110] As mentioned above, Figure 6 An adaptive tuning process is illustrated, comprising an iterative laser tuning process for tuning the junction resistance of a Josephson junction by implementing an asymptotic tuning method. This involves incrementally and progressively tuning the Josephson junction of a given multi-qubit device, for example, a qubit, so that the junction resistance is gradually adjusted toward a corresponding target junction resistance of the Josephson junction. In some embodiments, this is achieved by (i) the remaining resistance offset to reach the target junction resistance (denoted as...). (ii) is a function of the total annealing time previously used for laser annealing iterations applied to superconducting tunnels, adaptively determining the annealing time for a given tuning iteration at a given laser power level. This allows for adaptive and stepwise tuning of a given Josephson junction.

[0111] For example, the annealing time used to determine a given "irradiation" at a given laser power level ( An example function of ) is represented as follows:

[0112] ,

[0113] in This indicates the annealing number (or "irradiation" number), where Indicates the target junction resistance of a given Josephson junction ( The initial measured resistance of the given Josephson junction before the initial annealing operation (denoted as...) ) (exist The difference between (locations), and where express The current measured junction resistance of a given Josephson junction (denoted as...) The difference between the currently measured junction resistance and the calculated annealing time in a given iteration before applying the next "irradiation". Measurement. In other words, , ,and In the context of the adaptive tuning process, the parameters This represents the current junction resistance measured at the beginning of each successive iteration of the adaptive tuning process, and calculations are performed for each successive iteration of the adaptive tuning process. This is to determine the target annealing time for performing the laser annealing operation for a given iteration. In some embodiments, the laser power level used in each iteration is the laser power level initially selected for performing the initial laser annealing operation (initial irradiation).

[0114] In use for calculation In the example function, the ratio A weighting factor is provided, which represents the junction resistance based on an initial measurement from a given Josephson junction. Starting to reach the target junction resistance The required total resistance adjustment to reach the target junction resistance of a given Josephson junction. The percentage of the required remaining resistance adjustment. Additionally, summation. Provides all annealing times previously applied to a given Josephson junction (all determined) The total weighting factor for the total time (the sum of all times). Note that this is used for... The exemplary function provides a basis A linear combination of weighting factors for the product of total historical annealing time. In other embodiments, used for calculation The function can be based on other parameters and / or based on parameters. The total history annealing time is a nonlinear function of other parameters, which depends, for example, on the tuning characteristics of the Josephson junction determined by applying and / or based on associated tuning calibration data obtained using the calibration techniques discussed herein.

[0115] Based on functions The exemplary parameters, in a given iteration of the tuning process, indicate that if the measured junction resistance still indicates a relatively large amount of resistance adjustment is needed to reach the target junction resistance. The determined annealing time Will be weighted (by ratio) The resistance is longer. On the other hand, if a relatively small amount of resistance adjustment is required to reach the target junction resistance... Then the annealing time Will be weighted (by ratio) The length is relatively short. As another example, if in a given iteration of the tuning process (e.g., in a given...), Summation at ) If a relatively large total amount of annealing has already been performed on a given Josephson junction, then this provides an indication that the tuning of the given Josephson junction is slow, making the next annealing time... This will be weighted (by the total annealing time) to a relatively long duration. On the other hand, if the summation at a given iteration in the tuning process... If a relatively small annealing duration has already been performed on a given Josephson junction, then this provides an indication of a relatively fast tuning of the given Josephson junction, allowing for a faster next annealing time. It will be weighted (by total annealing time) to a relatively short value.

[0116] As discussed herein, the exemplary laser tuning method contrasts with conventional tuning methods, in which a single laser irradiation is used to tune the Josephson junction to a target junction resistance, which is unpredictable. The exemplary junction tuning technique disclosed herein is configured to perform an initial "irradiation" on a given Josephson junction to reduce the junction resistance from an initial resistance (…). Adjust to, for example, approximately the target junction resistance ( The junction resistance of a given Josephson junction is determined by taking 50% of its junction resistance and then iteratively tuning the junction resistance using multiple irradiations. The annealing time is adaptively determined for each irradiation to ensure a gradual approach to the target junction resistance, while also taking into account the relaxation of the junction resistance after laser annealing, which may require a delay to get closer to its final value. In an exemplary embodiment of laser tuning progression after the first irradiation, the process proceeds sequentially from the first junction to the last, with each junction being irradiated once in turn, and the process is repeated starting from the first junction. In this way, the first junction resistance has time to relax and stabilize near its final value before subsequent irradiations. In another embodiment of laser tuning progression after the first irradiation, each junction can be iteratively annealed until completion before annealing the next junction. In this case, a time delay can be implemented between successive annealing iterations on the same junction to allow the junction resistance to relax and stabilize near its final value, thereby improving the accuracy of approaching the resistance target.

[0117] Figure 7A A flowchart illustrating a method for focusing and aligning to a target Josephson junction in order to perform in-situ Josephson junction resistance measurement, according to exemplary embodiments of the present disclosure, is shown. In some embodiments, Figure 7A The following diagram illustrates the implementation. Figure 6 An exemplary process 700 for focusing / alignment processing is shown in box 402. The initial step of process 700 involves performing a coarse alignment, wherein the XYZ stage 142 is controllably operated to move the target Josephson node to be aligned with the center of the FOV of the microscope unit (box 701). The probe unit 140 is then controlled to scan the Z position of the XYZ stage 142 through a series of discrete steps (positions), and the camera 132 of the microscope unit 130 is controlled to capture and save a digital image (sample image) of the sample in the FOV at each Z position (box 702).

[0118] The tuning process then determines the sharpest sample image among multiple sample images taken at different Z positions (box 703). In some embodiments, the sharpest sample image is determined by using, for example, an edge detection process to identify the sample image with the sharpest edge (e.g., the sharpest edge of the contact pad that the electrical probe will contact). The XYZ stage 142 is then controlled to move to a target Z position corresponding to the sharpest sample image (box 704), where it is assumed that at the target Z position, the sample imaging plane with the contact pad is offset by a known distance (e.g., 70 micrometers) relative to the probe plane. Finally, an optional step of slightly adjusting the X and / or Y position of the quantum chip can be performed to provide some small offset from the original center alignment (box 705), which allows the probe tip of the electrical probe to contact the contact pad of a given Josephson junction at desired target contact positions, which differ from the contact positions with the contact pad in previous in-situ junction resistance measurements of previous iterations.

[0119] Figure 7B A flowchart is shown of a method for performing contact resistance and contact stability checks prior to performing in-situ Josephson junction resistance measurements, according to exemplary embodiments of the present disclosure. In some embodiments, Figure 7B The following diagram illustrates the implementation. Figure 6 The exemplary process 710 of the contact resistance and stability check process in box 603. The initial step of process 710 involves establishing a contact between the tip of the electrical probe and the contact pad of the Josephson junction using the same or similar methods discussed herein (box 711).

[0120] Next, the process continues, measuring the contact resistance between the electrical probe and the contact pads of the Josephson junction (box 712). The contact resistance is measured using known techniques. It is determined whether the measured contact resistance is less than a contact resistance threshold (box 713). If the measured contact resistance is determined to be less than the contact resistance threshold (affirmative judgment in box 713), the tuning process continues to determine whether the contact is stable (box 714). In some embodiments, a contact stability check is performed by repeatedly measuring the contact resistance over a given time period (e.g., 1-10 seconds) and determining whether the repeatedly measured contact resistance over the given time period remains less than the contact resistance threshold. Performing a contact stability check ensures that the electrical contact between the tip of the electrical probe and the contact pads of the Josephson junction is stable, because intermediate or intermittent contact during in-situ junction resistance measurement operations can cause voltage spikes and potentially damage the Josephson junction being measured.

[0121] In response to the determination that the electrical contact between the probe and the contact pad has low contact resistance and is stable (positive judgments in blocks 713 and 714), the tuning process continues, performing an in-situ junction resistance measurement operation to measure the resistance of the Josephson junction (block 715). On the other hand, if the contact resistance check or contact stability check fails (negative judgments in block 713 or block 714), the tuning process can skip the junction resistance measurement of that Josephson junction and move to the next Josephson junction, continuing the sequential cyclic tuning iterations for the next Josephson junction (block 716). In this case, remedial measures can be taken (e.g., cleaning the probe tip, or contacting a different area on the contact pad of the skipped Josephson junction) to ensure that the skipped Josephson junction can be tuned in subsequent iterations.

[0122] Figure 7C A flowchart illustrating a method for focusing and aligning to a target Josephson junction in order to perform a laser annealing process, according to exemplary embodiments of the present disclosure, is shown. In some embodiments, Figure 7C The following diagram illustrates the implementation. Figure 6An exemplary process 720 of the focusing / alignment process in box 606. The initial step of process 720 involves performing a coarse alignment process (box 721), wherein the XYZ stage 142 is controllably operated to, for example, return to a previously determined Z position as a focusing step performed for in-situ junction resistance measurement (e.g., box 704). Figure 7A As a result, the image plane is placed at or near the focal plane. In this case, it is assumed that the target Josephson node is returned to a position aligned (or nearly aligned) with the center of the FOV of the microscope unit (box 701). A pattern recognition operation is performed to determine the offset (if any) between the sample image of the Josephson node taken in the FOV and the template image of the Josephson node aligned to the center of the FOV (box 722). In some embodiments, the pattern recognition operation may be performed using the cross-correlation between the sample image and the template image to quantify the quality of the match and the corresponding offset (if any) required to optimize the match.

[0123] Next, it is determined whether the determined offset exceeds an offset threshold (box 723). For example, this determination can be made to determine whether the sample image of the Josephson junction in the FOV is offset by an amount exceeding the offset threshold in the X direction, Y direction, or both X and Y directions. If it is determined that the X offset and / or Y offset exceeds the offset threshold (affirmative judgment in box 723), the XYZ stage 142 is controllably moved by the determined offset in the X and / or Y directions to correct the misalignment in the X and / or Y directions (box 724), and the pattern recognition and offset determination steps are repeated (boxes 722 and 723). Once it is determined that the sample image of the Josephson junction in the FOV is aligned with the template image, the tuning process continues to the laser annealing operation (box 725).

[0124] Figure 7D The diagram schematically illustrates a process for aligning a contact probe and a laser spot to a Josephson junction of qubits according to an exemplary embodiment of the present disclosure. Specifically, Figure 7D An exemplary FOV 730 is schematically shown, which schematically illustrates a superconducting quantum bit 740. The superconducting quantum bit 740 comprises a transmon quantum bit consisting of a capacitor and a Josephson junction connected in parallel. Specifically, the superconducting quantum bit 740 includes a first superconducting pad 741, a second superconducting pad 742, and a Josephson junction 743 coupled to and disposed between the first and second superconducting pads 741 and 742. The first and second superconducting pads 741 and 742 comprise electrodes of a coplanar parallel-plate capacitor structure of the superconducting quantum bit 740. The Josephson junction 743 functions as a nonlinear inductor, forming an energy level (e.g., corresponding to the ground state) with individually addressable energy levels when shunt to the capacitor formed by the first and second superconducting pads 741 and 742. and the first excited state A non-resonant LC oscillator (with its two lowest energy levels) having a given transition frequency f 01 As described above, laser annealing is applied to the Josephson junction 743 to monotonically increase its junction resistance to the target junction resistance, which leads to an increase in the transition frequency f of the superconducting qubit 740. 01 Incrementally reduce to the target transition frequency.

[0125] FOV 730 represents the area of ​​the object imaged by microscope unit 130, where the size of the FOV is typically determined by the magnification of objective lens 137. In the exemplary camera-objective architecture of microscope unit 130, the FOV of the objective lens is applied to the image sensor (e.g., focal plane array) of camera 132. Since the image sensor is rectangular in shape, therefore... Figure 7D As shown, the image captured by the microscope unit 130 has a rectangular field of view (FOV) that does not capture the entire circular FOV from the objective lens 137.

[0126] Figure 7D An exemplary alignment process is schematically illustrated, wherein a plurality of electrical probes 750-1 and 750-2 (e.g., probe tips) are aligned and contacted with a first superconducting pad 741 and a second superconducting pad 742, the first superconducting pad 741 and the second superconducting pad 742 comprising electrodes of a coplanar parallel-plate capacitor of a superconducting quantum bit 740. Specifically, Figure 7D An electrical probe configuration for performing four-wire (Kelvin) resistance measurements is shown, wherein electrical probe 750-1 includes two probes contacting a first superconducting pad 741, and wherein electrical probe 750-2 includes two probes contacting a second superconducting pad 742. In this embodiment, the first superconducting pad 741 and the second superconducting pad 742 serve as contact pads for a Josephson junction 743, and the electrical probes rest on these contact pads to perform in-situ junction resistance measurements.

[0127] In some embodiments, the template image used to perform the pattern recognition alignment process includes an overall image of the superconducting qubit 740, including the first superconducting pad 741, the second superconducting pad 742, and the Josephson junction 743. In other embodiments, the template image used to perform the pattern recognition alignment process includes an image of the Josephson junction 743. In other embodiments, one or more additional features of the template image may be used to perform the pattern recognition alignment process.

[0128] Figure 7D An exemplary pattern of laser dots 760, which can be used for laser annealing of Josephson junction 743, is also shown. Specifically, the exemplary pattern of laser dots 760 includes four dots, corresponding to, for example, those formed by laser beam shaper 135. Figure 1The generated laser beams, implemented using a 2×2 diffraction beam splitter by the laser beam shaper 135, are projected onto the surface of the quantum chip 160 through the microscope unit 130. Figure 7D As schematically shown, the Josephson junction 743 is aligned in the field of view (FOV) 730 such that the laser beam dot pattern includes two laser dots positioned on one side (e.g., above) of the Josephson junction 743 and two laser dots positioned on the opposite side (e.g., below) of the Josephson junction 743, wherein the laser dots 760 are positioned to irradiate (and heat) a region of the upper surface of the quantum chip 160 adjacent to the Josephson junction 743, but not directly irradiate the Josephson junction 743. In other embodiments, other types of laser dot patterns can be used to laser anneal the Josephson junction 743. For example, different laser dot patterns include, for example, a 1-dot pattern, a 2-dot pattern, a 6-dot pattern, etc., depending on the geometry of the application and / or the feature being laser annealed.

[0129] It should be noted that, although Figure 7D A superconducting qubit 740 comprising a single Josephson junction 743 is shown, but other types of superconducting qubits or quantum devices can have multiple Josephson junctions, which can be simultaneously laser-annealed using a suitable laser dot pattern. For example, some quantum devices (such as tunable qubit couplers) include SQUIDs, where a SQUID comprises a pair of Josephson junctions connected in parallel to form a superconducting loop (called a SQUID loop), with an external magnetic flux... The operation of the tunable qubit coupler can be controlled through this superconducting loop. In this respect, the Josephson junctions of the SQUID can be simultaneously laser-annealed and tuned using a suitable laser dot pattern configured to heat the substrate region around the two Josephson junctions of the SQUID. It should also be noted that, although... Figure 7D The fixed-frequency qubit shown is a candidate for laser tuning using the exemplary laser tuning techniques disclosed herein, but it is to be understood that such exemplary techniques can be implemented to laser tune any quantum element including at least one Josephson junction, including but not limited to fixed-frequency transmon qubits, SQUID devices, etc.

[0130] Figure 8A This is a flowchart illustrating a method for performing an annealing operation to tune the junction resistance of a Josephson junction using a laser annealing apparatus combined with in-situ DC resistance measurement, according to exemplary embodiments of the present disclosure. Specifically, Figure 8A An exemplary process 800 for tuning the junction resistance of a Josephson junction using an overall thermal annealing stage is shown, which can be used, for example, with an exemplary electrical characterization system 440 ( Figure 4The overall thermal annealing stage is performed by a thermoelectric cooler 443 (e.g., a temperature-controlled wafer chuck system), followed by a target laser annealing stage. In some embodiments, the overall thermal annealing stage includes an initial step: performing an in-situ resistance measurement at room temperature to measure the junction resistance of the Josephson junction of a superconducting qubit in a given qubit lattice on a given quantum device (e.g., a quantum chip / wafer) (box 801).

[0131] The quantum device is then heated to a target temperature for a specified time (box 802) to perform a global thermal annealing process designed to adjust (increase) the junction resistance of the Josephson junction by a desired amount. The quantum device is then cooled back to room temperature (box 803), and an in-situ resistance measurement is performed at room temperature to remeasure the junction resistance of the Josephson junction. In an exemplary embodiment, the resistance measurement operations (boxes 801 and 804) include DC measurements performed using, for example, a four-wire (Kelvin) resistance measurement operation.

[0132] Following the overall thermal annealing stage, process 800 continues with a target laser annealing stage to laser tune the junction resistance of the Josephson junction to a corresponding target junction resistance. Specifically, process 800 generates a tuning scheme (box 805) for tuning the transition frequency of the superconducting qubit to a target transition frequency, wherein this tuning scheme is generated based on the currently measured junction resistance and determines the corresponding target junction resistance of the Josephson junction under certain constraints, such as the current junction resistance, the maximum tuning range achievable to adjust the current junction resistance of the Josephson junction to the target junction resistance, etc. Then, process 800 continues with a laser annealing operation based on the generated tuning scheme to laser tune the Josephson junction (box 806). For example, it can use, for instance... Figure 5 and Figure 6 The process is used to achieve laser tuning / annealing of the 806 block.

[0133] Figure 8B This is a flowchart illustrating a method for performing an annealing operation to tune the junction resistance of a Josephson junction using a laser annealing apparatus combined with in-situ DC resistance measurement, according to another exemplary embodiment of this disclosure. Specifically, Figure 8B An exemplary process 810 for tuning the junction resistance of a Josephson junction using a global thermal annealing stage is shown, which can be used, for example, with an exemplary electrical characterization system 440 ( Figure 4The overall thermal annealing stage is performed by a thermoelectric cooler 443 (e.g., a temperature-controlled wafer chuck system), followed by a target laser annealing stage. In some embodiments, the overall thermal annealing stage includes an initial step: performing an in-situ resistance measurement at a specified cryogenic temperature to measure the junction resistance of the Josephson junction of a superconducting qubit in a given qubit lattice on a given quantum device (e.g., a quantum chip / wafer), wherein the quantum device is cooled to the cryogenic temperature. Cryogenic resistance measurement provides more accurate resistance measurements (e.g., low-noise electrical measurements) and reduces the contribution of substrate conductivity to the junction resistance measurement.

[0134] The quantum device is then heated to a target temperature for a specified time (box 812) to perform a global thermal annealing process designed to adjust (increase) the junction resistance of the Josephson junction by a desired amount. The quantum device is then cooled back to the target cryogenic temperature (box 813), and an in-situ resistance measurement is performed while the quantum device is cooled to the cryogenic temperature to remeasure the junction resistance of the Josephson junction. In an exemplary embodiment, the resistance measurement operations (boxes 811 and 814) include DC measurements performed using, for example, a four-wire (Kelvin) resistance measurement operation.

[0135] Following the overall thermal annealing stage, process 810 continues with a target laser annealing stage to laser tune the junction resistance of the Josephson junction to a corresponding target junction resistance. Specifically, process 810 generates a tuning scheme (box 815) for tuning the transition frequency of the superconducting qubit to a target transition frequency, wherein this tuning scheme is generated based on the currently measured junction resistance and determines the corresponding target junction resistance of the Josephson junction under certain constraints, such as the current junction resistance, the maximum tuning range achievable to adjust the current junction resistance of the Josephson junction to the target junction resistance, etc. Then, process 810 continues with a laser annealing operation based on the generated tuning scheme to tune the Josephson junction (box 816). For example, it can be used... Figure 5 and Figure 6 The process is used to perform laser tuning / annealing operations on the 806.

[0136] Figure 9 This is a flowchart illustrating a method for performing an annealing operation to tune the junction resistance of a Josephson junction using a laser annealing apparatus combined with in-situ AC resistance measurement, according to exemplary embodiments of the present disclosure. Specifically, Figure 9 An exemplary process 900 for tuning the junction resistance of a Josephson junction using an overall thermal annealing stage is shown, which can be used, for example, with an exemplary electrical characterization system 440 ( Figure 4The overall thermal annealing stage is performed by a thermoelectric cooler 443 (e.g., a temperature-controlled wafer chuck system), followed by a target laser annealing stage. In some embodiments, the overall thermal annealing stage includes an initial step: performing an in-situ AC resistance measurement at a specified cryogenic temperature to measure the junction resistance of the Josephson junction of a superconducting qubit in a given qubit lattice on a given quantum device (e.g., a quantum chip / wafer), wherein the quantum device is cooled to the cryogenic temperature. Cryogenic resistance measurement provides a more accurate resistance measurement. Additionally, in some embodiments, the AC measurement is performed at a frequency of approximately 1.0 kHz or higher. High-frequency resistance measurements are configured to reduce 1 / f noise, thereby improving the accuracy of the junction resistance measurement.

[0137] The quantum device is then heated to a target temperature for a specified time (box 912) to perform a total thermal annealing process designed to adjust (increase) the junction resistance of the Josephson junction by a desired amount. The quantum device is then cooled back to the target cryogenic temperature (box 913), and an in-situ resistance measurement is performed using AC measurements while the quantum device is cooled to the cryogenic temperature to remeasure the junction resistance of the Josephson junction. In an exemplary embodiment, the resistance measurement operations (boxes 911 and 914) include AC measurements using, for example, a 4-wire (Kelvin) resistance measurement operation performed at cryogenic temperatures.

[0138] Following the overall thermal annealing stage, process 900 continues with a target laser annealing stage to laser tune the junction resistance of the Josephson junction to a corresponding target junction resistance. Specifically, process 900 generates a tuning scheme (box 915) for tuning the transition frequency of the superconducting qubit to a target transition frequency. This tuning scheme is generated based on the currently measured junction resistance and determines the corresponding target junction resistance of the Josephson junction under certain constraints, such as the current junction resistance, the maximum tuning range achievable to adjust the current junction resistance of the Josephson junction to the target junction resistance, etc. Process 900 then continues, performing a laser annealing operation based on the generated tuning scheme to tune the Josephson junction (box 916). For example, it can be used... Figure 5 and Figure 6 The process is used to perform laser tuning / annealing operations on the 916.

[0139] Various aspects of this disclosure are described by narrative text, flowcharts, block diagrams of computer systems, and / or block diagrams of machine logic included in computer program product (CPP) embodiments. Regarding any flowchart, depending on the technology involved, operations may be performed in a different order than shown in a given flowchart. For example, again depending on the technology involved, two operations shown in consecutive flowchart blocks may be performed in reverse order, as a single integrated step, simultaneously, or in a manner that at least partially overlaps.

[0140] Computer Program Product Embodiment (“CPP Embodiment” or “CPP”) is a term used herein to describe any collection of one or more storage media (also referred to as “media”) collectively included in a collection of one or more storage devices, the collection of one or more storage devices collectively including machine-readable code corresponding to instructions and / or data for performing computer operations specified in a given CPP claim. A storage device is any tangible device capable of holding and storing instructions for use by a computer processor. Without limitation, a computer-readable storage medium can be an electronic storage medium, a magnetic storage medium, an optical storage medium, an electromagnetic storage medium, a semiconductor storage medium, a mechanical storage medium, or any suitable combination of the foregoing. Some known types of storage devices that include these media include: floppy disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), optical disc read-only memory (CD-ROM), digital versatile optical disc (DVD), memory sticks, floppy disks, mechanical encoding devices (such as punched cards or pits / bumps formed on the main surface of the disk), or any suitable combination of the foregoing. As used herein, computer-readable storage media should not be construed as storing transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides, optical pulses transmitted through fiber optic cables, electrical signals communicated through wires, and / or other transmission media. As those skilled in the art will understand, data typically moves at some occasional point in time during normal operation of the storage device, such as during access, defragmentation, or garbage collection, but this does not make the storage device transient, because the data is not transient when it is stored.

[0141] Figure 10 The computing environment 1000 includes examples of environments for executing at least some computer code (box 1026), said computer code including data processing and control algorithms for performing various operations, such as laser annealing operations, imaging operations, machine learning pattern recognition operations, junction resistance measurement operations, tuning and calibration operations, and other computer-automated control and data processing operations discussed herein for performing various methods, such as those related to... Figure 1 , Figure 2A , Figure 2B , Figure 2C , Figure 3A , Figure 3B , Figure 4 , Figure 5 , Figure 6 , Figure 7A , Figure 7B , Figure 7C , Figure 7D , Figure 8A , Figure 8B and Figure 9In addition to box 1026, the computing environment 1000 also includes, for example, a computer 1001, a wide area network (WAN) 1002, an end-user equipment (EUD) 1003, a remote server 1004, a public cloud 1005, and a private cloud 1006. In this embodiment, the computer 1001 includes a processor set 1010 (including processing circuitry 1020 and a cache 1021), a communication structure 1011, volatile memory 1012, persistent storage 1013 (including an operating system 1022 and box 1026, as described above), a peripheral device set 1014 (including a user interface (UI) device set 1023, storage 1024, and an Internet of Things (IoT) sensor set 1025), and a network module 1015. The remote server 1004 includes a remote database 1030. Public cloud 1005 includes gateway 1040, cloud orchestration module 1041, host physical machine set 1042, virtual machine set 1043, and container set 1044.

[0142] Computer 1001 may take the form of a desktop computer, laptop computer, tablet computer, smartphone, smartwatch or other wearable computer, mainframe computer, quantum computer, or any form of computer or mobile device now known or to be developed in the future capable of running programs, accessing networks, or querying databases (such as remote database 1030). As is well known in the art of computer technology, and depending on the technology, the performance of a computer-implemented method can be distributed among multiple computers and / or distributed across multiple locations. On the other hand, in this presentation of computing environment 1000, the detailed discussion focuses on a single computer, specifically computer 1001, to keep the presentation as simple as possible. Computer 1001 may reside in the cloud, even if it is not physically present. Figure 10 The computer 1001 is displayed in the cloud. On the other hand, unless explicitly instructed otherwise, the computer 1001 does not need to be located in the cloud.

[0143] Processor set 1010 includes one or more types of computer processors, either currently known or to be developed in the future. Processing circuitry 1020 may be distributed across multiple packages, for example, multiple coordinated integrated circuit chips. Processing circuitry 1020 may implement multiple processor threads and / or multiple processor cores. Cache 1021 is a memory located within the processor chip package and typically used for data or code that should be readily accessible by the threads or cores running on processor set 1010. Cache memory is typically organized into multiple levels depending on its relative proximity to the processing circuitry. Alternatively, some or all of the processor set's cache may be located "off-chip". In some computing environments, processor set 1010 may be designed to work with qubits and perform quantum computing.

[0144] Computer-readable program instructions are typically loaded onto computer 1001 to cause processor set 1010 to perform a series of operational steps, thereby implementing a computer-implemented method such that the instructions executed thereby instantiate the method specified in the flowcharts and / or narrative descriptions of the computer-implemented method included in this document (collectively, the "inventive method"). These computer-readable program instructions are stored in various types of computer-readable storage media, such as cache 1021 and other storage media discussed below. Processor set 1010 accesses the program instructions and associated data to control and direct the execution of the inventive method. In computing environment 1000, at least some of the instructions for performing the inventive method may be stored in box 1026 of persistent storage 1013.

[0145] The communication structure 1011 includes signal transmission paths that allow various components of the computer 1001 to communicate with each other. Typically, this structure is made of switches and conductive paths, such as switches and conductive paths that constitute buses, bridges, physical input / output ports, etc. Other types of signal communication paths can be used, such as fiber optic communication paths and / or wireless communication paths.

[0146] Volatile memory 1012 is any type of volatile memory known now or to be developed in the future. Examples include dynamic random access memory (RAM) or static RAM. Typically, volatile memory is characterized by random access, but this is not necessary unless explicitly stated. In computer 1001, volatile memory 1012 is located in a single package and is internal to computer 1001; however, alternatively or additionally, volatile memory may be distributed across multiple packages and / or located externally to computer 1001.

[0147] Persistent storage 1013 is any form of non-volatile storage for a computer, now known or to be developed in the future. The non-volatility of this storage means that the stored data remains unchanged regardless of whether the computer 1001 and / or the persistent storage 1013 are powered. Persistent storage 1013 may be read-only memory (ROM), but typically at least a portion of persistent storage allows data to be written, deleted, and rewritten. Some familiar forms of persistent storage include hard disks and solid-state storage devices. Operating system 1022 can take many forms, such as various known proprietary operating systems or operating systems using an open-source portable operating system interface type with a kernel. The code included in box 1026 typically includes at least some computer code relating to performing the inventive methods.

[0148] Peripheral device set 1014 includes the peripheral device set of computer 1001. Data communication connections between peripheral devices and other components can be implemented in various ways, such as Bluetooth connections, near field communication (NFC) connections, connections established via cables (such as Universal Serial Bus (USB) type cables), plug-in connections (e.g., Secure Digital (SD) cards), connections established via local area communication networks, and even connections established via wide area networks (such as the Internet). In various embodiments, UI device set 1023 may include components such as displays, speakers, microphones, wearable devices (such as goggles and smartwatches), keyboards, mice, printers, touchpads, game controllers, and haptic devices. Storage 1024 is external storage, such as an external hard drive, or pluggable storage, such as an SD card. Storage 1024 can be persistent and / or volatile. In some embodiments, storage 1024 may take the form of a quantum computing storage device for storing data in the form of qubits. In cases where computer 1001 requires a large amount of memory (e.g., where computer 1001 locally stores and manages a large database), this storage can be provided by peripheral storage devices designed to store very large amounts of data, such as a storage area network (SAN) shared by multiple geographically distributed computers. The IoT sensor set 1025 consists of sensors that can be used in IoT applications. For example, one sensor could be a thermometer, and another could be a motion detector.

[0149] Network module 1015 is a collection of computer software, hardware, and firmware that allows computer 1001 to communicate with other computers via WAN 1002. Network module 1015 may include hardware such as a modem or Wi-Fi transceiver, software for packetizing and / or depacketizing data for transmission over a communication network, and / or web browser software for communicating data over the Internet. In some embodiments, the network control and network forwarding functions of network module 1015 are performed on the same physical hardware device. In other embodiments (e.g., embodiments utilizing software-defined networking (SDN), the control and forwarding functions of network module 1015 are performed on physically separate devices, such that the control functions manage several different network hardware devices. Computer-readable program instructions for performing the exemplary inventive methods can typically be downloaded to computer 1001 from a network adapter card or network interface included in network module 1015, which may be downloaded from an external computer or external storage device.

[0150] WAN 1002 is any wide area network (e.g., the Internet) capable of communicating computer data over non-local distances via any technology known now or to be developed in the future for communicating computer data. In some embodiments, a WAN can be replaced and / or supplemented by a local area network (LAN) designed to communicate data between devices located in a local area, such as a Wi-Fi network. WANs and / or LANs typically include computer hardware such as copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and edge servers.

[0151] End User Equipment (EUD) 1003 is any computer system used and controlled by an end user (e.g., an enterprise customer operating computer 1001) and can take any of the forms discussed above regarding computer 1001. EUD 1003 typically receives useful data from the operation of computer 1001. For example, in the hypothetical case where computer 1001 is designed to provide recommendations to an end user, these recommendations are typically sent from network module 1015 of computer 1001 to EUD 1003 via WAN 1002. In this way, EUD 1003 can display or otherwise present recommendations to the end user. In some embodiments, EUD 1003 can be a client device, such as a thin client, a thick client, a mainframe computer, a desktop computer, etc.

[0152] Remote server 1004 is any computer system that provides at least some data and / or functionality to computer 1001. Remote server 1004 can be controlled and used by the same entity operating computer 1001. Remote server 1004 represents a machine that collects and stores useful data for use by other computers, such as computer 1001. For example, in the case where computer 1001 is hypothetically designed and programmed to provide recommendations based on historical data, that historical data could be provided to computer 1001 from a remote database 1030 of remote server 1004.

[0153] Public cloud 1005 is any computer system that can be used by multiple entities, providing on-demand availability of computer system resources and / or other computing capabilities (especially data storage (cloud storage) and computing power) without direct, active management by the user. Cloud computing typically leverages resource sharing to achieve consistency and economies of scale. Direct and active management of the computing resources of public cloud 1005 is performed by the computer hardware and / or software of cloud coordination module 1041. The computing resources provided by public cloud 1005 are typically implemented by virtual computing environments running on various computers constituting host physical machine set 1042, which is a universe of physical computers in and / or available in public cloud 1005. Virtual computing environments (VCEs) typically take the form of virtual machines from virtual machine set 1043 and / or containers from container set 1044. It is understood that these VCEs can be stored as images and can be transferred between various physical machine hosts as images or after instantiation of the VCE. The cloud coordination module 1041 manages the delivery and storage of images, deploys new VCE instantiations, and manages the instantiation of active VCE deployments. Gateway 1040 is a collection of computer software, hardware, and firmware that allows the public cloud 1005 to communicate via WAN 1002.

[0154] Now, we will provide some further explanation of Virtualized Computing Environments (VCEs). A VCE can be stored as an "image." New active instances can be instantiated from this image. Two familiar types of VCEs are virtual machines and containers. A container is a VCE that uses operating system-level virtualization. This refers to an operating system feature where the kernel allows the existence of multiple isolated user-space instances (called containers). From the perspective of the programs running within them, these isolated user-space instances typically behave like a real computer. Computer programs running on a regular operating system can utilize all the resources of that computer, such as connected devices, files and folders, network shares, CPU power, and quantifiable hardware capabilities. However, programs running in containers can only use the contents of the container and the devices allocated to the container; this characteristic is called containerization.

[0155] Private cloud 1006 is similar to public cloud 1005, except that its computing resources are available only to a single enterprise. While private cloud 1006 is depicted communicating with WAN 1002, in other embodiments, private cloud may be completely disconnected from the internet and accessible only via a local / private network. A hybrid cloud consists of multiple clouds of different types (e.g., private, community, or public cloud types), typically implemented by different vendors. Each of the multiple clouds remains a separate and discrete entity, but the larger hybrid cloud architecture is united by standardized or proprietary technologies that enable coordination, management, and / or data / application portability across the multiple component clouds. In this embodiment, both public cloud 1005 and private cloud 1006 are part of a larger hybrid cloud.

[0156] The descriptions of the various embodiments disclosed herein are for illustrative purposes and are not intended to be exhaustive or to limit the embodiments to those disclosed. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles of the embodiments, practical applications of techniques found in the prior art, or technical improvements, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. An apparatus comprising: Optical devices; as well as Electrical characterization devices; The optical device and the electrical characterization device are integrated to perform a laser annealing operation for tuning the junction resistance of a superconducting tunnel junction device on a quantum chip, and to perform in-situ resistance measurement to measure the junction resistance of the superconducting tunnel junction device on the quantum chip.

2. The apparatus according to any one of the preceding claims, wherein, The optical device includes: A laser unit, comprising a laser source and optical components configured to generate one or more laser beams for performing the laser annealing operation; and An imaging unit, optically coupled to the laser unit, and configured to image a sample in the field of view of the laser unit.

3. The apparatus according to any one of the preceding claims, wherein, The optical device includes: A laser unit, the laser unit including a laser source configured to generate a laser beam; A modular microscope unit, comprising an optically integrated configuration of an imaging unit, optical components, a laser beam shaping device, and a laser beam focusing element; An optical fiber is configured to couple the laser beam output from the laser unit to the laser beam input of the modular microscope unit.

4. The apparatus according to any one of the preceding claims, wherein, The optical device includes an imager configured for computer vision imaging and inspection of the quantum chip.

5. The apparatus according to any one of the preceding claims, wherein, The optical device is configured such that the imaging plane corresponds to the laser focal plane.

6. The apparatus according to any one of the preceding claims, wherein, The electrical characterization device is configured to perform a direct current (DC) resistance measurement operation to measure the junction resistance of the superconducting tunnel junction device.

7. The apparatus according to any one of the preceding claims, wherein, The electrical characterization device is configured to perform an alternating current (AC) resistance measurement operation to measure the junction resistance of the superconducting tunnel junction device.

8. The apparatus according to any one of the preceding claims, wherein, The electrical characterization device includes a wafer probe, wherein the wafer probe includes at least one of an automated and semi-automated wafer probing system.

9. The apparatus according to any one of the preceding claims, wherein, The optical device and the electrical characterization device are integrated such that the detection plane is offset by a specified distance relative to the imaging plane.

10. The apparatus according to any one of the preceding claims, wherein, The electrical characterization device includes an environment chamber configured to control the environment surrounding the quantum chip during the laser annealing operation.

11. The apparatus according to claim 10, wherein, The environmental chamber is configured to control the surrounding environment by at least one of the following: (i) controlling the composition of one or more gases in the environmental chamber, and (ii) creating a vacuum in the environmental chamber.

12. The apparatus according to any one of the preceding claims, wherein, The electrical characterization device includes a thermal control system configured to perform at least one of the following: (i) heating the quantum chip to perform an overall thermal annealing operation for adjusting the junction resistance of the tunnel junction device of the quantum chip, and (ii) cooling the quantum chip to perform the in-situ resistance measurement.

13. A system comprising: Control system; as well as A laser annealing device coupled to the control system; The laser annealing apparatus includes an integrated configuration of optical devices and electrical characterization devices; The control system controls the laser annealing device to perform a laser annealing operation for tuning the junction resistance of the superconducting tunnel junction device on the quantum chip, and performs in-situ resistance measurement to measure the junction resistance of the superconducting tunnel junction device on the quantum chip.

14. The system according to claim 13, wherein, The control system controls the laser annealing apparatus to perform a DC resistance measurement operation to measure the junction resistance of the superconducting tunnel junction device.

15. The system according to any one of claims 13 to 14, wherein, The control system controls the laser annealing apparatus to perform an AC resistance measurement operation to measure the junction resistance of the superconducting tunnel junction device.

16. The system according to any one of claims 13 to 15, wherein: The laser annealing apparatus also includes an environmental chamber; and The control system is configured to control the surrounding environment of the environmental chamber during laser annealing operations, wherein the quantum chip is disposed in the chamber.

17. The system according to claim 16, wherein, The control system is configured to control the surrounding environment by at least one of the following: (i) controlling the composition of one or more gases in the environmental chamber, and (ii) creating a vacuum in the environmental chamber.

18. The system according to any one of claims 13 to 17, wherein, The laser annealing apparatus further includes a thermal control system configured to perform at least one of the following: (i) heating the quantum chip to perform an overall thermal annealing operation for adjusting the junction resistance of the tunnel junction device of the quantum chip, and (ii) cooling the quantum chip to perform the in-situ resistance measurement.

19. A method comprising: Performing an annealing operation to tune the junction resistance of a superconducting tunnel junction device on a quantum chip, wherein performing the annealing operation includes: Perform a thermal annealing operation to heat the quantum chip and thermally anneal the superconducting tunnel junction device to partially adjust the junction resistance of the superconducting tunnel junction device to a corresponding target junction resistance of the superconducting tunnel junction device; Following the thermal annealing operation, a resistance measurement of the superconducting tunnel junction device is performed to measure the corresponding junction resistance of the superconducting tunnel junction device; and A laser annealing operation is performed on the superconducting tunnel junction device to adjust the junction resistance of the superconducting tunnel junction device from its corresponding measured junction resistance to its corresponding target junction resistance.

20. The method according to claim 19, wherein, The annealing operation is performed by a laser annealing device to tune the junction resistance of the superconducting tunnel junction device on the quantum chip. The laser annealing device is configured to perform the thermal annealing operation, the resistance measurement, and the laser annealing operation in situ.

21. The method according to claim 20, wherein, In-situ resistance measurement includes alternating current (AC) resistance measurement.

22. The method according to any one of claims 20 to 21, further comprising cooling the quantum chip in situ to a target temperature after the thermal annealing operation, and performing the in-situ resistance measurement of the superconducting tunnel junction device while the quantum chip is cooled to the target temperature.

23. The method according to any one of claims 19 to 22, wherein: The superconducting tunnel junction device includes a Josephson junction of a corresponding superconducting qubit device in a given lattice on the quantum chip; as well as The target junction resistance of the corresponding superconducting tunnel junction device includes a target junction resistance specified in a tuning scheme for tuning the transition frequency of the superconducting qubit device to the corresponding target transition frequency determined by the tuning scheme.

24. A method comprising performing a laser tuning process using a laser annealing apparatus to tune the junction resistance of a superconducting tunnel junction device on a quantum chip, the laser annealing apparatus performing a laser annealing operation to laser tune the junction resistance of the superconducting tunnel junction device, and performing an in-situ resistance measurement to measure the junction resistance of the superconducting tunnel junction device on the quantum chip.

25. A computer program product for laser tuning, the computer program product comprising: One or more computer-readable storage media, and program instructions commonly stored on the one or more computer-readable storage media, the program instructions comprising: Program instructions are provided for using a laser annealing apparatus to perform a laser tuning process to tune the junction resistance of a superconducting tunnel junction device on a quantum chip, wherein the laser annealing apparatus performs a laser annealing operation to laser tune the junction resistance of the superconducting tunnel junction device, and performs an in-situ resistance measurement to measure the junction resistance of the superconducting tunnel junction device on the quantum chip.

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