Impedance adjusting device and method for Josephson junction of quantum chip

Abstract

The embodiment of the invention provides an impedance adjusting device and method for a Josephson junction of a quantum chip. The impedance adjusting device comprises a laser; the coupling head is used for focusing the laser emitted by the laser so as to form a light spot on a transparent quantum chip; and the impedance sensor is pressed at the Josephson junction to be measured on the quantum chip in a touching manner and is used for sensing the impedance of the Josephson junction to be measured while adjusting the light spot, and stopping adjusting the light spot until the sensed impedance reaches preset impedance. According to the embodiment of the invention, the impedance adjustment efficiency is improved, and the adjustment period is shortened. The embodiment of the invention can be applied to various scenes such as quantum chip testing and superconducting quantum chip manufacturing.

Description

Technical Field

[0001] The present disclosure relates to the field of quantum technologies, and particularly to an impedance adjustment device and method for Josephson junctions of a quantum chip. Background Art

[0002] The core device of a qubit unit in a quantum chip is a Josephson junction. Generally, there are 1 - 2 Josephson junctions in one qubit unit. The qubit unit operates relying on the Josephson junction. The Josephson junction has a certain impedance, and this impedance determines the frequency of the qubit.

[0003] There is a prior art solution for separately adjusting the impedance of the Josephson junction of a single qubit unit. It is in a laser - hitting device, where a laser is irradiated onto the quantum chip through the laser to change the impedance of the Josephson junction. Then it is taken to another impedance - measuring device to measure the impedance change of the Josephson junction. If it is not ideal, it goes back to the laser - hitting device to hit the laser again. Through the repeated process of hitting the laser, then measuring, hitting the laser again, and then measuring again, the impedance adjustment is completed.

[0004] The disadvantages of the prior art are that the efficiency of impedance adjustment is low and the period is long. Summary of the Invention

[0005] Embodiments of the present disclosure provide an impedance adjustment device and method for Josephson junctions of a quantum chip, which improve the efficiency of impedance adjustment and shorten the adjustment period.

[0006] According to one aspect of the present disclosure, there is provided an impedance adjustment device for Josephson junctions of a quantum chip, including:

[0007] A laser;

[0008] A coupling head, configured to focus the laser emitted by the laser to form a light spot on the transparent quantum chip;

[0009] An impedance sensor, pressed against the Josephson junction to be measured on the quantum chip, configured to sense the impedance of the Josephson junction to be measured while adjusting the light spot, and stop adjusting the light spot until the sensed impedance reaches a predetermined impedance.

[0010] Optionally, the transparency is full transparency; the impedance adjustment device further includes:

[0011] A microscope, located on opposite sides of the quantum chip from the coupling head, configured to observe the light spot transmitted from the quantum chip while adjusting the light spot.

[0012] Optionally, the impedance adjustment device further includes a base and a first displacement stage. The first displacement stage is mounted on the base to fix the coupling head. The first displacement stage is used to move the coupling head to adjust the position of the light spot on the quantum chip.

[0013] Optionally, the first displacement stage includes a first-direction adjuster, a second-direction adjuster, and a third-direction adjuster. The first direction, the second direction, and the third direction are perpendicular to each other pairwise. The third-direction adjuster is used for focusing to form the light spot on the quantum chip, and the first-direction adjuster and the second-direction adjuster are used to adjust the position of the light spot.

[0014] Optionally, the base has a first connection structure, and the first displacement stage has a second connection structure. The first connection structure cooperates with the second connection structure to mount the first displacement stage on the base.

[0015] Optionally, the impedance adjustment device includes a fixture base and a clamping arm extending from the fixture base. The clamping arm presses against the quantum chip on the opposite side of the coupling head to fix the quantum chip.

[0016] Optionally, the impedance adjustment device further includes a base and a second displacement stage. The second displacement stage is mounted on the base to fix the fixture base. The second displacement stage is used to move the clamping arm to clamp the quantum chip.

[0017] Optionally, the base has a third connection structure, and the second displacement stage has a fourth connection structure. The third connection structure cooperates with the fourth connection structure to mount the second displacement stage on the base.

[0018] Optionally, the impedance adjustment device further includes a support structure and an impedance sensor base mounted on the support structure. The impedance sensor is mounted in the impedance sensor base and extends towards the direction of the Josephson junction to be measured to press against the position of the Josephson junction to be measured.

[0019] Optionally, the impedance adjustment device further includes a support rod extending from the base towards the quantum chip and a top seat integrally connected to the support rod. The microscope hangs down from the top seat.

[0020] Optionally, the support rod includes a first section, a second section, and a telescopic rod located between the first section and the second section. The relative distance between the microscope and the quantum chip in the third direction is adjusted by the length of the telescopic rod.

[0021] Optionally, a fourth direction adjuster and a fifth direction adjuster are provided on the top seat. The fourth direction adjuster is used to move the microscope in a first direction, and the fifth direction adjuster is used to move the microscope in a second direction, so that the microscope is aligned with the quantum chip in a third direction, where the first direction, the second direction, and the third direction are perpendicular to each other in pairs.

[0022] According to one aspect of the present disclosure, a method for adjusting the impedance of a Josephson junction of a quantum chip is provided for an impedance adjustment device. The impedance adjustment device includes a laser, a coupling head, a microscope, and an impedance sensor. The quantum chip is a transparent quantum chip. The method includes:

[0023] Focus the laser light emitted by the laser through the coupling head to form a light spot on the quantum chip as observed from the microscope.

[0024] Move the coupling head in a direction parallel to the quantum chip so that the distance between the light spot and the Josephson junction to be measured is a first distance as observed from the microscope.

[0025] Touch the impedance sensor to the Josephson junction to be measured, and while adjusting the light spot, sense the impedance of the Josephson junction to be measured until the sensed impedance reaches a predetermined impedance, and then stop adjusting the light spot.

[0026] Optionally, the laser has a minimum power. The step of sensing the impedance of the Josephson junction to be measured while adjusting the light spot until the sensed impedance reaches a predetermined impedance and then stopping adjusting the light spot includes:

[0027] Initialize the target laser power to the minimum power.

[0028] Execute a first process. The first process includes: opening the shutter of the laser. If the sensed impedance gradually increases within a predetermined time period and reaches a stable impedance, determine whether the stable impedance reaches the predetermined impedance. If not, close the shutter of the laser, increase the target laser power by a predetermined power step, and repeat the first process until the stable impedance reaches the predetermined impedance.

[0029] Optionally, the laser also has a maximum power. After executing the first process, the method further includes:

[0030] Initialize the target distance to the first distance.

[0031] Execute a second process, which includes: if the stable impedance has not reached the predetermined impedance after the laser has reached the maximum power, reduce the target distance by the predetermined distance step, and change the target laser power to the minimum power; move the coupling head in a direction parallel to the quantum chip so that, as observed from the microscope, the distance between the light spot and the Josephson junction to be measured is the target distance; execute the first process; repeat the second process until the stable impedance reaches the predetermined impedance.

[0032] Optionally, the coupling head is located on a first displacement stage, and the first displacement stage includes a first-direction regulator and a second-direction regulator. The first direction is perpendicular to the second direction, the first direction is parallel to the quantum chip, and the second direction is parallel to the quantum chip.

[0033] The step of moving the coupling head in a direction parallel to the quantum chip so that, as observed from the microscope, the distance between the light spot and the Josephson junction to be measured is the first distance includes: moving the coupling head in the first direction through the first-direction regulator, and moving the coupling head in the second direction through the second-direction regulator so that, as observed from the microscope, the distance between the light spot and the Josephson junction to be measured is the first distance.

[0034] Optionally, the step of moving the coupling head in the first direction through the first-direction regulator and moving the coupling head in the second direction through the second-direction regulator so that, as observed from the microscope, the distance between the light spot and the Josephson junction to be measured is the first distance includes:

[0035] Obtain an observation screenshot of the quantum chip by the microscope;

[0036] In the observation screenshot, obtain the first screenshot coordinates of the Josephson junction to be measured and the second screenshot coordinates of the light spot;

[0037] Utilize the correspondence between the screenshot coordinates and the actual coordinates to determine the first actual coordinates of the Josephson junction to be measured based on the first screenshot coordinates and determine the second actual coordinates of the light spot based on the second screenshot coordinates;

[0038] Based on the first actual coordinates and the first distance, determine the target actual focusing coordinates;

[0039] Based on the second actual coordinates and the target actual focusing coordinates, calculate the first actual moving distance of the light spot in the first direction and the second actual moving distance of the light spot in the second direction;

[0040] Based on the actual moving distance of the first light spot, drive the first-direction adjuster to move the coupling head in the first direction, and based on the actual moving distance of the second light spot, drive the second-direction adjuster to move the coupling head in the second direction.

[0041] Optionally, the first displacement stage further includes a third-direction adjuster, the third direction is perpendicular to the first direction, and the third direction is perpendicular to the second direction;

[0042] Focusing the laser light emitted by the laser through the coupling head for observation from the microscope to form a light spot on the quantum chip includes:

[0043] Move the coupling head in the third direction through the third-direction adjuster so that, as observed from the microscope, the light spot is focused on the quantum chip.

[0044] Optionally, before moving the coupling head in the third direction through the third-direction adjuster so that, as observed from the microscope, the light spot is focused on the quantum chip, the method further includes:

[0045] Move the coupling head in the first direction through the first-direction adjuster and move the coupling head in the second direction through the second-direction adjuster so that, as observed from the microscope, the light spot is formed in an area outside the qubit unit in the quantum chip in the microscope field of view.

[0046] Optionally, the impedance adjustment device further includes a top base to which the microscope is fixed, the top base includes a fourth-direction adjuster and a fifth-direction adjuster, the first direction is perpendicular to the second direction, the first direction is parallel to the quantum chip, and the second direction is parallel to the quantum chip;

[0047] Before focusing the laser light emitted by the laser through the coupling head for observation from the microscope to form a light spot on the quantum chip, the method further includes:

[0048] Move the microscope in the first direction through the fourth-direction adjuster and move the microscope in the second direction through the fifth-direction adjuster so that the microscope is aligned with the quantum chip.

[0049] Optionally, the impedance adjustment device further includes a base and a support rod extending from the base towards the quantum chip direction, the support rod is integrally connected to the top base, and the support rod includes a first section, a second section, and a telescopic rod located between the first section and the second section;

[0050] After moving the microscope in the first direction through the fourth direction adjuster and moving the microscope in the second direction through the fifth direction adjuster so that the microscope is aligned with the quantum chip, the method further includes:

[0051] Adjusting the length of the telescopic rod so that the quantum chip can be observed from the microscope at the maximum magnification of the microscope.

[0052] In the embodiments of the present disclosure, the impedance adjustment device for the Josephson junction of the quantum chip includes a laser, a coupling head, and an impedance sensor. The quantum chip is a transparent quantum chip. When the coupling head focuses the laser emitted by the laser on the quantum chip, the impedance sensor real-time senses the impedance of the Josephson junction to be measured on the quantum chip. In this way, while adjusting the light spot, the impedance of the Josephson junction to be measured is sensed until the sensed impedance reaches a predetermined impedance, and then the adjustment of the light spot is stopped. It can be seen that the embodiments of the present disclosure can observe the impedance while adjusting the light spot, and can perform impedance adjustment without separately firing a laser and then separately measuring the impedance, which improves the efficiency of adjusting the impedance of the Josephson junction in the quantum chip and shortens the adjustment period.

[0053] The method for adjusting the impedance of the Josephson junction of the quantum chip proposed in the embodiments of the present disclosure belongs to the same inventive concept as the impedance adjustment device for the Josephson junction of the quantum chip, and therefore has the same beneficial effects.

[0054] Other features and advantages of the present disclosure will be described in the following specification, and part of them will become obvious from the specification, or will be understood by implementing the present disclosure. The objectives and other advantages of the present disclosure can be achieved and obtained through the structures specifically pointed out in the specification, claims, and drawings. Description of the Drawings

[0055] The drawings are used to provide a further understanding of the technical solutions of the present disclosure, and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the technical solutions of the present disclosure, and do not constitute a limitation to the technical solutions of the present disclosure.

[0056] Figure 1 It is the first structural schematic diagram of the impedance adjustment device for the Josephson junction of the quantum chip;

[0057] Figure 2 It is the second structural schematic diagram of the impedance adjustment device for the Josephson junction of the quantum chip;

[0058] Figure 3 It is the third structural schematic diagram of the impedance adjustment device for the Josephson junction of the quantum chip;

[0059] Figure 4 It is the structural schematic diagram of the second displacement stage;

[0060] Figure 5 is a flowchart of a method for adjusting the impedance of a Josephson junction of a quantum chip according to an embodiment of the present disclosure;

[0061] Figure 6 is Figure 5 a detailed flowchart of step 550 in

[0062] Figure 7 is Figure 6 a schematic diagram of the observation screenshot in step 610 in

[0063] Figure 8 is Figure 6 a schematic diagram of the specific implementation of obtaining the first screenshot coordinate and the second screenshot coordinate from the observation screenshot in step 620 in

[0064] Figure 9 is Figure 6 a schematic diagram of the correspondence between the screenshot coordinate and the actual coordinate in step 630 in

[0065] Figure 10 is a schematic diagram of the distance between the light spot observed by the microscope and the Josephson junction to be measured being the first distance;

[0066] Figure 11 is Figure 5 a first detailed flowchart of step 560 in

[0067] Figure 12 is Figure 5 a second detailed flowchart of step 560 in

[0068] Figure 13 is a specific implementation detail diagram of a method for adjusting the impedance of a Josephson junction of a quantum chip according to an embodiment of the present disclosure.

[0069] Reference numerals in the drawings: impedance adjustment device 1000 for the Josephson junction of the quantum chip, laser 1010, coupling head 1020, microscope 1030, impedance sensor 1040, probe 1041, base 1050, first connection structure 1051, third connection structure 1052, first displacement stage 1060, first direction regulator 1061, second direction regulator 1062, third direction regulator 1063, fixture base 1070, clamping arm 1080, second displacement stage 1090, sixth direction regulator 1091, seventh direction regulator 1092, eighth direction regulator 1093, support structure 1100, impedance sensor seat 1110, support rod 1120, first section 1121, second section 1122, telescopic rod 1123, top seat 1130, fourth direction regulator 1131, fifth direction regulator 1132, fixing device 1140, host computer 1150, quantum chip 2000. Detailed implementation manners

[0070] In order to make the objectives, technical solutions and advantages of the present disclosure clearer and more understandable, the present disclosure will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present disclosure, and are not used to limit the present disclosure.

[0071] In the embodiments of the present disclosure, prefix words such as "first", "second", and "third" are only used to distinguish different described objects, and have no limiting effect on the position, order, priority, quantity, content, etc. of the described objects. The use of ordinal words and other prefix words for distinguishing described objects in the embodiments of the present application does not constitute a limitation on the described objects. For the statements of the described objects, reference may be made to the description in the claims or the context of the embodiments. It should not constitute an unnecessary limitation because of the use of such prefix words. In addition, in the description of the present embodiment, unless otherwise specified, the meaning of "a plurality" is two or more.

[0072] The reference to "some embodiments" described in this specification means that in one or more embodiments of the present application, specific features, structures or characteristics described in combination with the embodiment are included. Thus, the statements "in some embodiments" etc. that appear in different places in this specification do not necessarily refer to the same embodiments, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0073] The "vertical" involved in the present application is not strictly vertical, but within the allowable error range. The "parallel" is not strictly parallel, but within the allowable error range.

[0074] In the embodiments of the present disclosure, the same reference numeral represents the same component or the same part. In the embodiments of the present disclosure, for multiple identical parts, only one of the parts may be marked with a reference numeral in the drawings. The reference numeral is equally applicable to other identical parts or components. In addition, the sizes and dimensions of the parts shown in the drawings are only exemplary.

[0075] Before further elaborating on the embodiments of the present disclosure, the nouns and terms involved in the embodiments of the present disclosure are described. The nouns and terms involved in the embodiments of the present disclosure are applicable to the following explanations:

[0076] Qubit: In quantum informatics, it is the measurement unit of quantum information. Different from the classical bit that can only be in one of the states 0 or 1, the qubit can be in both the 0 and 1 states at the same time, that is, the quantum superposition state of 0 and 1.

[0077] Quantum Chip: A chip that utilizes the principles of quantum mechanics for computing and storing information. Different from traditional binary computers, quantum chips use qubits (quantum bits) to store and process data instead of classical bits in traditional computers. Qubits have superconducting properties and can exist in a superposition of multiple states simultaneously, enabling quantum chips to have the capabilities of parallel computing and processing quantum entanglement. Quantum chips include superconducting quantum chips, ion trap quantum chips, quantum dot quantum chips, topological quantum chips, etc. A quantum chip generally consists of a substrate, a qubit unit structure, and other structures. The qubit unit structure is mainly based on Josephson junctions.

[0078] Josephson Junction: Also known as a superconducting tunnel junction. Generally, it is a structure composed of two superconductors sandwiching a very thin barrier layer (thickness ≤ the coherence length of Cooper electron pairs), such as the S (Superconductor) - I (semiconductor or insulator (Insulator)) - S (superconductor) structure, abbreviated as SIS. In a Josephson junction, superconducting electrons can pass through the semiconductor or insulator thin film from one side to the other through the tunneling effect.

[0079] The core device of the qubit unit in a quantum chip is the Josephson junction. Generally, there are 1 - 2 Josephson junctions in one qubit unit. The qubit unit operates relying on the Josephson junction. The Josephson junction has a certain impedance, and this impedance determines the frequency of the qubit.

[0080] When fabricating a quantum chip, generally, many quantum chips are set on a 2 - inch wafer. There will be dozens to hundreds of Josephson junctions on each quantum chip. A wafer is processed as a whole, that is, dozens to hundreds of Josephson junctions on the wafer are processed simultaneously. Due to process limitations, the impedances of the fabricated Josephson junctions may not be processed exactly the same. After processing, the way to continue adjusting the impedance of the Josephson junction is to heat it again to change the impedance. Currently, generally, the entire quantum chip is heated together, and the impedance of a single Josephson junction cannot be adjusted individually. If individual adjustment can be carried out to change the impedance of a single qubit unit's junction, it will greatly improve the yield of the qubit chip.

[0081] There is a related technology solution for individually adjusting the impedance of the Josephson junction of a single qubit unit. This solution is in a laser - hitting device. By irradiating the qubit chip with a laser, the impedance of the Josephson junction is changed. Then it is taken to another impedance - measuring device to measure the impedance change of the Josephson junction. If it is not ideal, it goes back to the laser - hitting device to hit the laser again. Through such a repeated process of hitting the laser and then measuring, and then hitting the laser again and measuring again, the efficiency is low and the cycle is long.

[0082] Based on this, an impedance adjustment device for Josephson junctions of a quantum chip is proposed in an embodiment of the present disclosure. In the impedance adjustment device of the embodiment of the present disclosure, the quantum chip is a transparent quantum chip. For example, a transparent double-polished sapphire chip substrate is selected. A coupling head for emitting laser to the quantum chip, a microscope for observing the position of the laser irradiation, and an impedance sensor for measuring impedance are tightly coupled in the impedance adjustment device, realizing real-time laser irradiation and real-time measurement. Specifically, the coupling head focuses the laser of the laser on the back of the chip. Since the double-polished sapphire chip substrate is transparent, a microscope is placed on the other side of the quantum chip, and the microscope can observe the position of the light spot formed by the laser. On the other hand, the impedance sensor is tightly clamped on the quantum chip to measure the impedance in real time. In this way, during the impedance adjustment process, when the sensed impedance has not reached the expected impedance, the light spot can be observed through the microscope and adjusted in real time, so that the sensed impedance gradually reaches the predetermined impedance. The entire impedance adjustment process is carried out in real time and continuously, without going through isolated repeated processes of measuring after laser irradiation, then irradiating the laser again and then measuring again, improving the adjustment efficiency and reducing the adjustment cost.

[0083] Figure 1 is a partial structural schematic diagram of an impedance adjustment device for Josephson junctions of a quantum chip. Please refer to Figure 1 , an embodiment of the present disclosure provides an impedance adjustment device 1000 for Josephson junctions of a quantum chip. The impedance adjustment device 1000 for Josephson junctions of a quantum chip includes: a laser 1010, a coupling head 1020, and an impedance sensor 1040 (in Figure 1 , the impedance sensor 1040 is represented by a dotted rectangular box). The coupling head 1020 is used to focus the laser emitted by the laser 1010 to form a light spot on the transparent quantum chip 2000. The impedance sensor 1040 is pressed against the Josephson junction to be measured on the quantum chip 2000, and is used to sense the impedance of the Josephson junction to be measured while adjusting the light spot until the sensed impedance reaches the predetermined impedance, and then stop adjusting the light spot.

[0084] Specifically, after the laser emitted by the laser 1010 irradiates the Josephson junction to be measured in the quantum chip 2000, the impedance of the Josephson junction to be measured is higher than that before irradiation. If the laser is adjusted, the Josephson junction to be measured will have a higher impedance with the adjusted laser, but the specific impedance value cannot be known. In the related art, in order to solve the problem that the impedance cannot be known after the above laser irradiation, an impedance measuring instrument is used alone to measure the impedance after the laser irradiation. However, the disadvantage of doing this is that if the impedance has not reached the predetermined impedance, it is necessary to irradiate the laser again and then re-measure the impedance, which is very cumbersome and inefficient.

[0085] To solve the problem of cumbersome impedance adjustment described above, in the embodiments of the present disclosure, the quantum chip 2000 is a transparent quantum chip. Since laser can penetrate the material and generate local heating on its surface or inside, generally the material needs to have a certain transparency so that the laser can effectively penetrate and heat the material. Therefore, the quantum chip 2000 is usually transparent during the impedance adjustment process so that the laser can effectively act on the surface or inside of the quantum chip 2000. The transparency referred to in this embodiment includes translucent and fully transparent. Translucent means that the package of the quantum chip 2000 is transparent, but the quantum chip 2000 itself is not transparent. Fully transparent means that the package of the quantum chip 2000 is transparent and the quantum chip 2000 itself is transparent. The quantum chip 2000 in this embodiment can be translucent or fully transparent, as long as it can ensure that the Josephson junction to be measured of the quantum chip 2000 can change the impedance under the irradiation of the light spot. When using laser to irradiate the Josephson junction to be measured of the quantum chip, while adjusting the light spot to adjust the impedance, it is possible to observe in real time from the impedance sensor whether the impedance of the Josephson junction to be measured reaches the predetermined impedance.

[0086] Regarding the specific process of how to adjust the light spot, it will not be introduced here and will be described in detail in the method embodiments below.

[0087] The impedance adjustment device 1000 for the Josephson junction of the quantum chip provided by the embodiments of the present disclosure has at least the following advantages: It eliminates the cumbersome process of separately performing laser irradiation and then separately measuring the impedance, improves the efficiency of adjusting the impedance of the Josephson junction in the quantum chip, and shortens the adjustment cycle.

[0088] In one embodiment, the quantum chip 2000 includes a substrate, a superconducting circuit layer, an under-bump metal layer, and solder joints from bottom to top. The fact that the quantum chip 2000 itself mentioned above is transparent may mean that the substrate of the quantum chip 2000 is transparent. For example, the substrate of the quantum chip is a transparent double-polished sapphire.

[0089] The above-mentioned laser 1010 is a device that generates a highly focused, highly monochromatic, high-brightness, and good coherence beam. It generates a laser beam through the process of stimulated emission. The basic components of a laser include the following parts: an active medium, a pump source, an optical cavity, a mirror, an optical compensation device, and a control and electronic system. The working principle of a laser is to generate a laser beam through the process of stimulated emission. In the active medium, with the energy provided by the pump source, atoms or molecules in the medium are excited to higher energy levels, forming an excited state. When these excited-state particles return to the ground state, they emit photons, producing an optical amplification effect. These photons are reflected back and forth in the optical cavity. After being enhanced and amplified, a part of them is transmitted through the output mirror to form a laser beam. The laser in the embodiments of the present disclosure may be a fiber laser. A fiber laser uses an optical fiber as the active medium. Common fiber lasers include fiber light sources and fiber Raman lasers, etc. In one example, the laser outputs a laser wavelength of 532 nm and an output power of 50 mW - 700 mW.

[0090] The above-mentioned coupling head 1020 refers to a device that effectively couples the output beam of a laser to an optical fiber or other optical devices. It is usually composed of a lens, an optical fiber interface, an adjustment mechanism, etc. The main function of the coupling head is to achieve efficient energy transfer and beam quality matching between the laser and the optical fiber. By adjusting the position and angle of the lens in the coupling head, the focusing and coupling efficiency of the beam can be optimized to ensure that the laser energy is coupled into the optical fiber to the maximum extent. The design and selection of the coupling head need to consider multiple factors, including the output characteristics of the laser (such as beam diameter, divergence angle), the characteristics of the optical fiber (such as core diameter, numerical aperture), and application requirements, etc. Different types of lasers and optical fibers may require different types of coupling heads. Therefore, when selecting a coupling head, it needs to be matched according to specific situations. In the embodiments of the present disclosure, the coupling head is used to form a light spot of the laser emitted by the laser on the quantum chip.

[0091] Please refer to Figure 1 and Figure 2 , in some embodiments, the impedance adjustment device 1000 for the Josephson junction of the quantum chip further includes: a first displacement stage 1060. The first displacement stage 1060 is used to move the coupling head 1020 to adjust the position of the light spot on the quantum chip 2000.

[0092] The above-mentioned first displacement stage 1060 is a device for precisely adjusting the position of a device or a working platform. It is usually composed of adjustable guide rails and sliders and can achieve small displacements in the horizontal or vertical directions. The first displacement stage 1060 has precise scales and adjustment mechanisms to facilitate fine-tuning and positioning. The first displacement stage 1060 can be operated by means of a manual knob, a screw, an electric drive, or a pneumatic drive, etc., to achieve precise position adjustment and positioning.

[0093] The advantage of setting the first displacement stage 1060 in the embodiments of the present disclosure is that by moving the coupling head 1020 through the first displacement stage 1060, the purpose of adjusting the spot position is achieved, improving the convenience and accuracy of position adjustment.

[0094] It should be noted that the first displacement stage 1060 has a certain weight and size, and can remain relatively stable when moving the coupling head, so as to accurately adjust the position of the spot. In another embodiment, in order to further improve the accuracy of adjusting the spot, the first displacement stage 1060 is also installed on a more stable structure.

[0095] Please refer to Figure 1 and Figure 2 , in this embodiment, the impedance adjustment device 1000 for the Josephson junction of the quantum chip further includes: a base 1050 and a first displacement stage 1060. The first displacement stage 1060 is installed on the base 1050 to fix the coupling head 1020. The first displacement stage 1060 is used to move the coupling head 1020 to adjust the position of the spot on the quantum chip 2000.

[0096] The above base 1050 is a stable support platform, usually made of a solid material (such as metal), and is used to provide stable support and fix devices or work platforms. The base 1050 usually has a solid structure and a flat surface to ensure the stability and reliability of the device or work platform.

[0097] The advantage of setting the first displacement stage 1060 and the base 1050 in the embodiments of the present disclosure is that the base 1050 provides stable support for the first displacement stage 1060, so that when using the first displacement stage 1060 to move the coupling head 1020, the stability of the first displacement stage 1060 can be ensured. More flexible and precise position adjustment and positioning are achieved.

[0098] Please refer to Figure 2 , in some embodiments, the first displacement stage 1060 includes a first direction regulator 1061, a second direction regulator 1062, and / or a third direction regulator 1063. The first direction, the second direction, and the third direction are perpendicular to each other in pairs. Specifically, in a three-dimensional space rectangular coordinate system, the first direction is the horizontal axis direction, the second direction is the vertical axis direction, and the third direction is the vertical axis direction. The position of the spot can be adjusted by adjusting the first direction regulator 1061, the second direction regulator 1062, and / or the third direction regulator 1063.

[0099] Please refer to Figure 2, in some embodiments, the first displacement stage 1060 includes a first direction regulator 1061, a second direction regulator 1062, and a third direction regulator 1063. The first direction, the second direction, and the third direction are perpendicular to each other pairwise. The third direction regulator 1063 is used for focusing to form a light spot on the quantum chip, and the first direction regulator 1061 and the second direction regulator 1062 are used for adjusting the position of the light spot.

[0100] The above-mentioned third direction regulator 1063 refers to a tool for adjusting the coupling head 1020 in the third direction to form a light spot on the quantum chip. For example, the third direction regulator 1063 moves a third distance in the third direction, so that the coupling head 1020 focuses the laser onto the quantum chip 2000 to form a light spot.

[0101] The position of the light spot includes the first direction light spot position and the second direction light spot position.

[0102] The above-mentioned first direction regulator 1061 refers to a tool for adjusting the first direction light spot position of the light spot in the first direction. The above-mentioned second direction regulator 1062 refers to a tool for adjusting the second direction light spot position of the light spot in the second direction.

[0103] The advantage of simultaneously setting the first direction regulator 1061, the second direction regulator 1062, and the third direction regulator 1063 in the embodiments of the present disclosure is that the coupling head 1020 can be adjusted in three directions, and the formation of the light spot on the quantum chip 2000 and the adjustment of the position of the light spot can be realized respectively, improving the adjustment flexibility.

[0104] Please refer to Figure 2 , in some embodiments, the base 1050 has a first connection structure 1051, and the first displacement stage 1060 has a second connection structure (not shown). The first connection structure 1051 cooperates with the second connection structure (not shown) to mount the first displacement stage 1060 on the base 1050.

[0105] The above-mentioned first connection structure 1051 can be a through hole, a screw hole, and the second connection structure can be a screw, a stud, etc. For example, the first connection structure 1051 is a screw hole, and the second connection structure is a screw. The screw hole cooperates with the screw to mount the first displacement stage 1060 on the base 1050. It should be noted that appropriate types and sizes of screws need to be selected to ensure the cooperation of the pre-drilled hole of the screw hole with the screw, and follow the correct fastening steps and standards to ensure the quality and reliability of the connection.

[0106] It should be noted that the first displacement stage 1060 can be mounted on the base 1050 by fixed connection methods such as welding or riveting.

[0107] The advantages of using the first connection structure and the second connection structure in cooperation for installation in the embodiments of the present disclosure include: The first connection structure and the second connection structure are relatively easy to disassemble, making it more convenient to repair and replace components, and having high dismountability and repairability; The tightness of the connection can be adjusted by adjusting the tightness of the first connection structure and the second connection structure, and it has high adjustability.

[0108] In one embodiment, the transparent quantum chip is fully transparent. Please refer to Figure 1 , the impedance adjustment device 1000 for the Josephson junction of the quantum chip further includes: a microscope 1030, located on opposite sides of the quantum chip 2000 from the coupling head 1020, for observing the light spot transmitted from the quantum chip 2000 while adjusting the light spot.

[0109] The advantage of this embodiment is that when using a laser to irradiate the Josephson junction to be measured of the quantum chip, in addition to being able to observe in real time from the resistor sensor whether the resistance of the Josephson junction to be measured reaches a predetermined resistance, it is also possible to observe in real time from the microscope the light spot transmitted from the fully transparent quantum chip. It realizes the adjustment of the light spot when the light spot is observed, which can improve the controllability of the light spot adjustment, and further improve the adjustment accuracy.

[0110] The above microscope 1030 is an optical instrument for observing small objects. It magnifies the details of the object so that people can see microscopic structures that cannot be distinguished by the naked eye. The basic structure of the microscope includes components such as an objective lens, an eyepiece, a light source, and a focusing device. The objective lens is a lens placed below the object, which magnifies the details of the object and forms a real image. The eyepiece is a lens placed above the objective lens, which further magnifies the real image of the object so that it can be observed by the human eye. The light source is usually an adjustable light bulb or laser for illuminating the object. The focusing device can adjust the focal length by moving the objective lens or the eyepiece to make the object clearly visible. According to different optical paths, microscopes can be divided into two major categories: optical microscopes and electron microscopes. The microscope in the embodiments of the present disclosure can be an optical microscope.

[0111] Please refer to Figure 1 , in some embodiments, the impedance adjustment device 1000 for the Josephson junction of the quantum chip further includes: a host computer 1150. The host computer 1150 can obtain the observation screenshot of the quantum chip 2000 by the microscope 1030, and the observation screenshot includes the Josephson junction to be measured and the light spot. According to the observation screenshot, the moving displacement required to adjust the light spot can be determined, and then the position of the light spot can be automatically adjusted. Regarding the specific process of how to determine it, it will not be introduced here first and will be described in detail in the method embodiments below.

[0112] The above-mentioned host computer 1150 refers to a computer or computer system that communicates with and controls a device or system. It is usually used for tasks such as control, configuration, and data processing. The host computer 1150 can be a computer (PC), workstation, server, embedded system, etc. The host computer 1150 can communicate with various devices or systems, such as a laser 1010, a coupling head 1020, a microscope 1030, an impedance sensor 1040, etc. If the host computer 1150 communicates with the laser 1010, it can control the power of the laser emitted by the laser 1010. If the host computer 1150 communicates with the coupling head 1020, it can control the movement of the coupling head 1020 to adjust the position of the light spot on the quantum chip. If the host computer 1150 communicates with the microscope 1030, it can obtain an observation screenshot of the quantum chip 2000 by the microscope 1030. If the host computer 1150 communicates with the impedance sensor 1040, it can obtain the impedance of the Josephson junction to be measured sensed by the impedance sensor 1040.

[0113] In one embodiment, the host computer 1150 includes components such as a radio frequency (RF) circuit, a memory, an input unit, a display unit, a sensor, an audio circuit, a wireless fidelity (WiFi) module, a processor, and a power supply. The RF circuit can be used for receiving and sending signals during information reception or call processes. Specifically, after receiving the downlink information from the base station, it is given to the processor for processing; in addition, the data designed for uplink is sent to the base station. The memory can be used to store software programs and modules. The processor executes various functional applications and data processing of the terminal by running the software programs and modules stored in the memory. The input unit can be used to receive input digital or character information and generate key signal inputs related to the settings and function controls of the terminal. Specifically, the input unit can include a touch panel and other input devices. The display unit can be used to display the input information or the provided information and various menus of the terminal. The display unit can include a display panel. The audio circuit, speaker, and microphone can provide an audio interface. In this embodiment, the processor included in the host computer can obtain an observation screenshot of the quantum chip 2000 by the microscope 1030. The observation screenshot contains the Josephson junction to be measured and the light spot. Then, according to the observation screenshot, the movement displacement required to adjust the light spot can be determined, and then the position of the light spot can be automatically adjusted.

[0114] The advantage of automatically adjusting the position of the light spot by the host computer in the embodiments of the present disclosure is that there is no need to manually adjust the light spot, which improves the adjustment efficiency and accuracy.

[0115] Please refer to Figure 3, in some embodiments, the impedance adjustment device 1000 for the Josephson junctions of the quantum chip further includes: a support rod 1120 extending from the base 1050 towards the quantum chip, and a top seat 1130 integrally connected to the support rod 1120, and the microscope 1030 is suspended from the top seat 1130.

[0116] The above-mentioned support rod 1120 and top seat 1130 provide a stable support platform for the microscope 1030, ensuring that the microscope 1030 remains stable during impedance adjustment. This is very important for precise operation and measurement, especially under the microscope observation that requires high resolution. The extension of the support rod 1120 and the connection of the top seat 1130 can accurately position and adjust the position of the microscope 1030. In this way, the distance and angle between the microscope 1030 and the quantum chip 2000 can be accurately controlled to obtain clear images and accurate measurement results. The design of the support rod 1120 and the top seat 1130 is simple and intuitive, easy to operate and use. This can reduce the risk of operation errors and damage, and improve the work efficiency and comfort of the operator.

[0117] The advantage of the embodiment of the present disclosure in setting the support rod 1120 and the top seat 1130 to suspend the top seat 1130 lies in its high stability and precision.

[0118] Please refer to Figure 3 , in some embodiments, the support rod 1120 includes a first section 1121, a second section 1122, and a telescopic rod 1123 located between the first section 1121 and the second section 1122. The relative distance between the microscope 1030 and the quantum chip 2000 in the third direction is adjusted by adjusting the length of the telescopic rod 1123.

[0119] The above-mentioned support rod 1120 is a structure for supporting the microscope 1030 or other devices, usually composed of multiple parts. In this embodiment, the support rod 1120 includes a first section 1121, a second section 1122, and a telescopic rod 1123. The first section 1121 and the second section 1122 have fixed lengths. The telescopic rod 1123 can adjust its length to adjust the relative distance between the microscope 1030 and the quantum chip 2000 in the third direction.

[0120] Since the above-mentioned first section 1121 and second section 1122 have fixed lengths, the first section 1121 and the second section 1122 include solid metal rods, tubular rods, etc. Solid metal rods are the most common type, made of metal materials (such as aluminum, stainless steel, etc.), with fixed lengths and diameters. They usually have high strength and stability and are suitable for supporting heavier devices. Tubular rods are made of metal or plastic, with fixed lengths and inner and outer diameters. They are usually lighter and are suitable for supporting relatively light devices.

[0121] The above-mentioned telescopic rod 1123 is usually composed of two or more parts, and its length can be adjusted by locking or unlocking the positions of the parts. For example, one part is an inner pipe or column, and the other part is an outer pipe or column. The inner pipe or column can be slidably placed inside the outer pipe or column to adjust the length of the telescopic rod. The length of the telescopic rod can be adjusted by locking or unlocking the positions of the inner and outer pipes or columns. The length of the telescopic rod can be adjusted as needed to adapt to different application scenarios.

[0122] The advantage of the support rod 1120 in the embodiment of the present disclosure including the first section 1121, the second section 1122, and the telescopic rod 1123 is that by adjusting the length of the telescopic rod 1123, precise control of the relative distance between the microscope 1030 and the quantum chip 2000 in the third direction can be achieved. This is very important for operations and measurements that require high-resolution microscope observation. By arranging the telescopic rod 1123 between the first section 1121 and the second section 1122, the stability and accuracy of adjusting the relative distance are further improved. In addition, the length of the telescopic rod 1123 can be adjusted according to the size and shape of the quantum chip 2000. This can adapt to the designs and requirements of different quantum chips 2000, providing better compatibility and flexibility.

[0123] Please refer to Figure 3 , in some embodiments, the top seat 1130 is provided with a fourth-direction adjuster 1131 and a fifth-direction adjuster 1132. The fourth-direction adjuster 1131 is used to move the microscope 1030 in the first direction, and the fifth-direction adjuster 1132 is used to move the microscope 1030 in the second direction, so that the microscope 1030 is aligned with the quantum chip 2000 in the third direction, where the first direction, the second direction, and the third direction are perpendicular to each other in pairs.

[0124] Specifically, in a three-dimensional space rectangular coordinate system, the first direction is the horizontal axis direction, the second direction is the vertical axis direction, and the third direction is the vertical axis direction.

[0125] The above-mentioned fourth-direction adjuster 1131 refers to a tool for moving the position of the microscope 1030 in the first direction. The above-mentioned fifth-direction adjuster 1132 refers to a tool for moving the position of the microscope 1030 in the second direction.

[0126] The advantage of the embodiment of the present disclosure setting the fourth-direction adjuster 1131 and the fifth-direction adjuster 1132 is that the microscope 1030 can be moved in the first direction and the second direction, improving the flexibility of moving the microscope 1030.

[0127] The above-mentioned impedance sensor 1040 is an instrument for sensing impedance. Please refer to Figure 1 and Figure 2, in some embodiments, the impedance adjustment device 1000 for the Josephson junction of the quantum chip further includes: a support structure 1100, and an impedance sensor seat 1110 mounted on the support structure 1100. The impedance sensor 1040 is mounted in the impedance sensor seat 1100 and extends towards the Josephson junction to be measured, so as to press against the position of the Josephson junction to be measured.

[0128] Specifically, when performing impedance adjustment, the impedance sensor 1040 needs to press against the Josephson junction to be measured on the quantum chip 2000 and maintain a stable press. In the embodiments of the present disclosure, the impedance sensor is mounted in the impedance sensor seat 1100, and the impedance sensor seat is mounted on the support structure 1100. Since the impedance sensor seat and the support structure are relatively stable structures, therefore, it can greatly ensure that the impedance sensor 1040 can stably and accurately press against the position of the Josephson junction to be measured and will not slide randomly.

[0129] The advantage of setting the support structure 1100 and the impedance sensor seat 1110 in the embodiments of the present disclosure is that it can improve the stability of the impedance sensor pressing against the Josephson junction to be measured.

[0130] Please refer to Figure 1 and Figure 2 , in some embodiments, the impedance sensor 1040 includes: a probe 1041, and a source meter (not shown) electrically connected to the probe 1041. The probe 1041 is inserted into the capacitance region of the Josephson junction to be measured, and the source meter real-time displays the impedance of the Josephson junction to be measured.

[0131] The above probe 1041 refers to a probe, which is a contact tool used to connect the test equipment and the device under test. The probe is usually composed of a fine metal probe tip and can precisely contact the pins or circuit nodes on the device.

[0132] The above source meter (Source Measure Unit, abbreviated as SMU) is a test instrument used to perform electrical performance tests on devices. It integrates a voltage source, a current source, and a measurement function, can provide a stable voltage or current output, and can simultaneously measure parameters such as current, voltage, and resistance value.

[0133] Specifically, the probe 1041 is used to introduce the electrical signal of the source meter into the Josephson junction to be measured, or to lead out the electrical signal on the Josephson junction to be measured to the source meter for measurement. By the combined use of the probe 1041 and the source meter, the impedance of the Josephson junction to be measured can be accurately measured.

[0134] It can be understood that although in Figure 2 the probe 1041 is not pressing against the Josephson junction to be measured, but compared with Figure 1Similarly, when performing impedance adjustment, the probe 1041 presses against the Josephson junction to be measured in the quantum chip 2000.

[0135] The advantage of setting the impedance sensor 1040 as the probe 1041 and the source meter in the embodiments of the present disclosure is that two probes 1041 can be used to form conductive connections with the electrodes on both sides of the Josephson junction to be measured respectively, so that the source meter can display the impedance of the Josephson junction to be measured according to the electrical signal, improving the accuracy of impedance measurement.

[0136] Please refer to Figure 2 , in some embodiments, the impedance adjustment device 1000 for the Josephson junction of the quantum chip includes a fixture base 1070 and a clamping arm 1080 extending from the fixture base 1070. The clamping arm 1080 presses against the quantum chip 2000 on the opposite side of the coupling head 1020 to fix the quantum chip 2000.

[0137] The above-mentioned fixture base 1070 and clamping arm 1080 can provide stable support and fixation, ensuring that the quantum chip 2000 remains stable during operation and use. This is very important for the precise operation and measurement of the quantum chip 2000 because the quantum system is very sensitive to external interference. The clamping arm 1080 can precisely control and adjust the pressing force on the quantum chip 2000. This can ensure a tight contact between the quantum chip 2000 and the impedance sensor 1040, minimizing signal transmission loss and improving the performance and efficiency of the quantum chip 2000. The designs of the fixture base 1070 and clamping arm 1080 usually have adjustable characteristics and can be adjusted according to the size and shape of the quantum chip 2000. This can adapt to different quantum chip designs and requirements, providing better compatibility and flexibility. The fixture base 1070 and clamping arm 1080 can provide a physical barrier and protection to prevent dust, particulate matter and other contaminants from entering the quantum chip 2000, thereby extending the service life and reliability of the quantum chip 2000. The designs of the fixture base 1070 and clamping arm 1080 are usually simple and intuitive, easy to operate and use. This can reduce the risk of operation errors and damage and improve the work efficiency and comfort of the operator.

[0138] It should be noted that when designing and using the fixture base 1070 and clamping arm 1080, it is necessary to ensure the low thermal conductivity, low noise and low vibration characteristics of their materials to minimize the interference to the quantum chip 2000. In addition, appropriate fixture base 1070 and clamping arm 1080 should be selected according to the specific design and requirements of the quantum chip 2000 to ensure their compatibility and reliability with the quantum chip 2000.

[0139] The advantage of setting the fixture base 1070 and the clamping arm 1080 to fix the quantum chip 2000 in the embodiments of the present disclosure is that it has relatively high stability, accuracy, adjustability, safety, and ease of operation.

[0140] Please refer to Figure 2 and Figure 3 , in some embodiments, the impedance adjustment device 1000 for the Josephson junction of the quantum chip further includes a fixing device 1140. The fixing device 1140 is used to fix the clamping arm 1080 extending from the fixture base 1070.

[0141] The above fixing device 1140 can be a stud, and the fixture base 1070 is provided with a threaded hole so that the stud can be screwed into the threaded hole of the fixture base 1070. While fixing the clamping arm 1080, the tightening degree of the clamping arm 1080 for clamping the quantum chip 2000 can be adjusted.

[0142] The advantage of setting the fixing device 1140 in the embodiments of the present disclosure is that when the clamping arm 1080 is used to clamp the quantum chip 2000, the clamping arm 1080 can be stably fixed. And the fixing device is convenient to disassemble, improving the adjustability of the clamping arm 1080 for clamping the quantum chip 2000.

[0143] Please refer to Figure 2 , in some embodiments, the impedance adjustment device 1000 for the Josephson junction of the quantum chip further includes: a second displacement stage 1090, and the second displacement stage 1090 is used to move the clamping arm 1080 to clamp the quantum chip 2000.

[0144] The above second displacement stage 1090 is a device for precisely adjusting the position of a device or a working platform. It usually consists of adjustable guide rails and sliders and can achieve micro-displacements in the horizontal or vertical directions. The second displacement stage 1090 has precise scales and adjustment mechanisms for easy fine-tuning and positioning. The second displacement stage 1090 can be operated by means of a manual knob, a screw, an electric drive, a pneumatic drive, etc. to achieve precise position adjustment and positioning.

[0145] The advantage of setting the second displacement stage 1090 in the embodiments of the present disclosure is that by moving the clamping arm 1080 through the second displacement stage 1090 to clamp the quantum chip 2000, the convenience and safety of clamping the quantum chip are improved.

[0146] It should be noted that the second displacement stage 1090 has a certain weight and size and can remain relatively stable when moving the clamping arm, so as to accurately adjust the position of the light spot. In another embodiment, in order to further improve the accuracy of clamping the quantum chip 2000, the second displacement stage 1090 is further installed on a more stable structure.

[0147] Please refer toFigure 2 In this embodiment, the impedance adjustment device 1000 for the Josephson junction of the quantum chip further includes: a base 1050 and a second displacement stage 1090. The second displacement stage 1090 is mounted on the base 1050 to fix the fixture seat 1070. The second displacement stage 1090 is used to move the clamping arm 1080 to clamp the quantum chip 2000.

[0148] The above-mentioned base 1050 is a stable support platform, usually made of a solid material (such as metal), and is used to provide stable support and fix devices or work platforms. The base 1050 usually has a solid structure and a flat surface to ensure the stability and reliability of the devices or work platforms.

[0149] The advantage of setting the second displacement stage 1090 and the base 1050 in the embodiments of the present disclosure is that the base 1050 provides stable support for the second displacement stage 1090, so that when the second displacement stage 1090 is used to move the clamping arm 1080, the stability of the second displacement stage 1090 can be ensured. More flexible and precise position adjustment and positioning are achieved.

[0150] Please refer to Figure 2 , in some embodiments, the base 1050 has a third connection structure 1052, and the second displacement stage 1090 has a fourth connection structure (not shown). The third connection structure 1052 cooperates with the fourth connection structure (not shown) to mount the second displacement stage 1090 on the base 1050.

[0151] The above-mentioned third connection structure 1052 can be a through hole or a screw hole, and the fourth connection structure can be a screw, a stud, etc. For example, the third connection structure 1052 is a screw hole, and the fourth connection structure is a screw. The screw hole cooperates with the screw to mount the second displacement stage 1090 on the base 1050. It should be noted that appropriate types and sizes of screws need to be selected to ensure that the pre-drilled hole of the screw hole cooperates with the screw, and follow the correct fastening steps and standards to ensure the quality and reliability of the connection.

[0152] The advantages of using the third connection structure and the fourth connection structure to cooperate for installation in the embodiments of the present disclosure include: the third connection structure and the fourth connection structure are relatively easy to disassemble, making maintenance and replacement of components more convenient, and having high dismountability and maintainability; the fastening degree of the connection can be adjusted by adjusting the fastening degree of the third connection structure and the fourth connection structure, and it has high adjustability.

[0153] Please refer to Figure 4, in some embodiments, the second displacement stage 1090 includes a sixth-direction adjuster 1091, a seventh-direction adjuster 1092, and an eighth-direction adjuster 1093. The sixth-direction adjuster 1091 is configured to move the quantum chip in a first direction. The seventh-direction adjuster 1092 is configured to move the quantum chip in a second direction. The eighth-direction adjuster 1093 is configured to move the quantum chip in a third direction. The first direction, the second direction, and the third direction are perpendicular to each other pairwise. In a three-dimensional rectangular coordinate system, the first direction is the horizontal axis direction, the second direction is the vertical axis direction, and the third direction is the vertical axis direction.

[0154] The advantage of providing the fourth-direction adjuster 1091, the fifth-direction adjuster 1092, and the eighth-direction adjuster 1093 in the embodiments of the present disclosure is that the quantum chip 2000 can be adjusted in three directions, improving the adjustment flexibility.

[0155] The method for adjusting the impedance of the Josephson junction of the quantum chip provided by the embodiments of the present invention will be described in detail below.

[0156] Referring to Figure 5 , in some embodiments, the embodiments of the present invention provide a method for adjusting the impedance of the Josephson junction of a quantum chip. Referring to Figure 1 , this method is used for the impedance adjustment device 1000, which includes a laser 1010, a coupling head 1020, a microscope 1030, and an impedance sensor 1040. The quantum chip 2000 is a transparent quantum chip. This method includes but is not limited to steps 540 to 560:

[0157] Step 540: Focus the laser emitted by the laser through the coupling head to form a light spot on the quantum chip as observed from the microscope;

[0158] Step 550: Move the coupling head in a direction parallel to the quantum chip so that, as observed from the microscope, the distance between the light spot and the Josephson junction to be measured is a first distance;

[0159] Step 560: Press the impedance sensor against the Josephson junction to be measured to sense the impedance of the Josephson junction to be measured while adjusting the light spot until the sensed impedance reaches a predetermined impedance, and then stop adjusting the light spot.

[0160] The advantage of the embodiments of steps 540-560 is that there is no need for the cumbersome process of separately performing laser irradiation and then separately measuring the impedance, improving the efficiency of adjusting the impedance of the Josephson junction in the quantum chip and shortening the adjustment cycle.

[0161] In one embodiment, referring to Figure 3, the impedance adjustment device 1000 further includes: a top seat 1130 to which the microscope 1030 is fixed, and the top seat 1130 includes a fourth-direction adjuster 1131 and a fifth-direction adjuster 1132. The first direction is perpendicular to the second direction, the first direction is parallel to the quantum chip, and the second direction is parallel to the quantum chip. In this embodiment, before step 540, the method for adjusting the impedance of the Josephson junction of the quantum chip according to an embodiment of the present disclosure may further include: step 510, moving the microscope in the first direction by the fourth-direction adjuster and moving the microscope in the second direction by the fifth-direction adjuster, so that the microscope is aligned with the quantum chip.

[0162] In addition to step 510, other alignment algorithms or alignment methods can also be used to adjust the microscope 1030. Since step 510 is optional, it is Figure 5 represented by a dashed box.

[0163] Specifically, in this step 510, the fourth-direction adjuster 1131 and the fifth-direction adjuster 1132 are involved, as well as the alignment of the microscope 1030 and the quantum chip 2000. First, as described above, the microscope 1030 is an optical instrument for observing tiny objects. It usually consists of an eyepiece and an objective lens, magnifying the details on the sample through the objective lens and observing through the eyepiece. The quantum chip 2000 refers to a tiny chip used to implement quantum computing, which contains qubits and related circuits and components. When aligning the microscope 1030 and the quantum chip 2000, the position of the microscope 1030 needs to be adjusted to make it completely aligned with the quantum chip 2000. This can be achieved by the fourth-direction adjuster 1131 and the fifth-direction adjuster 1132. The fourth-direction adjuster 1131 is usually used to move the microscope 1030 in the horizontal direction. By adjusting the fourth-direction adjuster 1131, the microscope 1030 can be aligned with the quantum chip 2000 in the horizontal direction. The fifth-direction adjuster 1132 is usually used to move the microscope 1030 in the vertical direction. By adjusting the fifth-direction adjuster 1132, the microscope 1030 can be aligned with the quantum chip 2000 in the vertical direction.

[0164] The advantage of this step 510 is that by simultaneously adjusting the fourth-direction adjuster 1131 and the fifth-direction adjuster 1132, fine adjustment of the microscope 1030 in the horizontal and vertical directions can be achieved, so that it is completely aligned with the quantum chip 2000. This alignment process is very important because when observing and operating the quantum chip 2000, it is necessary to ensure that the microscope 1030 can accurately focus on the quantum chip 2000 to obtain clear images and accurate operations.

[0165] In one embodiment, referring to Figure 3, the impedance adjustment device 1000 further includes: a base 1050, and a support rod 1120 extending from the base 1050 towards the quantum chip 2000. The support rod 1120 is integrally connected to the top base 1130. The support rod 1120 includes a first section 1121, a second section 1122, and a telescopic rod 1123 located between the first section 1121 and the second section 1122. In this embodiment, after step 510, the method for adjusting the impedance of the Josephson junction of the quantum chip according to an embodiment of the present disclosure may further include: step 520, by adjusting the length of the telescopic rod, so that the quantum chip can be observed by the microscope at the maximum magnification of the microscope.

[0166] In addition to step 520, other adjustment methods can also be used to achieve the adjustment of the microscope 1030. Since step 520 is optional, it is represented by a dashed box in Figure 5 this figure.

[0167] In this step 520, it involves adjusting the length of the telescopic rod 1123 so as to observe the quantum chip 2000 from the microscope 1030 at the maximum magnification. The telescopic rod 1123 is a device for adjusting the distance between the microscope 1030 and the quantum chip 2000. The telescopic rod 1123 can be composed of a telescopic rod and a clamping device fixed at both ends on the first section and the second section. When it is desired to observe the quantum chip 2000 at the maximum magnification of the microscope 1030, the length of the telescopic rod 1123 needs to be adjusted. By increasing or decreasing the length of the telescopic rod 1123, the distance between the microscope 1030 and the quantum chip 2000 can be changed, thereby adjusting the focal length and magnification. Specifically, when the length of the telescopic rod 1123 is longer, the distance between the microscope 1030 and the quantum chip 2000 is farther, the focal length is longer, and the observed image will be smaller. On the contrary, when the length of the telescopic rod 1123 is shorter, the distance between the microscope 1030 and the quantum chip 2000 is closer, the focal length is shorter, and the observed image will be larger.

[0168] The advantage of this step 520 is that by adjusting the length of the telescopic rod 1123, the microscope 1030 can observe the quantum chip 2000 at the maximum magnification. In this way, a higher magnification can be obtained to more clearly observe the details and structures on the quantum chip 2000.

[0169] In one embodiment, referring to Figure 2, the coupling head 1020 is located on the first displacement stage 1060. The first displacement stage 1060 includes a first-direction adjuster 1061 and a second-direction adjuster 1062. The first direction is perpendicular to the second direction. The first direction is parallel to the quantum chip 2000, and the second direction is parallel to the quantum chip 2000. In this embodiment, before step 510, the method for adjusting the impedance of the Josephson junction of the quantum chip according to an embodiment of the present disclosure may further include: step 530, moving the coupling head in the first direction through the first-direction adjuster, and moving the coupling head in the second direction through the second-direction adjuster, so that from the microscope observation, the light spot is formed in the area outside the qubit unit in the quantum chip in the microscope field of view.

[0170] In addition to step 530, other adjustment methods can also be used to adjust the coupling head 1020. Since step 530 is optional, it is Figure 5 represented by a dashed box.

[0171] In this step 530, the movement of the first-direction adjuster 1061, the second-direction adjuster 1062, and the coupling head 1020 is involved, so that from the microscope 1030, it can be observed that the light spot is formed in the area outside the qubit unit in the quantum chip 2000 in the field of view. First of all, the coupling head 1020 refers to an optical device for focusing a light beam onto the quantum chip. It is usually composed of a lens or an optical fiber, etc. During the process of adjusting the position of the light spot, the first-direction adjuster 1061 and the second-direction adjuster 1062 are needed to move the coupling head 1020. The first-direction adjuster 1061 is usually used to move the coupling head in the horizontal direction. By adjusting the first-direction adjuster 1061, the coupling head 1020 can be aligned with the quantum chip 2000 in the horizontal direction. The second-direction adjuster 1062 is usually used to move the coupling head in the vertical direction. By adjusting the second-direction adjuster 1062, the coupling head 1020 can be aligned with the quantum chip 2000 in the vertical direction.

[0172] The advantage of this step 530 is that by simultaneously adjusting the first-direction adjuster 1061 and the second-direction adjuster 1062, fine adjustment of the coupling head 1020 in the horizontal and vertical directions can be achieved, so that the light spot is formed in the area outside the qubit unit in the quantum chip in the microscope field of view. This adjustment process is very important because when observing the quantum chip, it is desired to accurately focus the light spot in the area outside the qubit unit. This can avoid the interference of the light spot on the qubit unit, and at the same time, it can better observe and analyze the environment and structure around the qubit unit.

[0173] In one embodiment, referring to Figure 2, the first displacement stage 1060 further includes a third-direction adjuster 1063, where the third direction is perpendicular to the first direction and perpendicular to the second direction. In this embodiment, step 540 includes: moving the coupling head in the third direction through the third-direction adjuster so that, as observed from the microscope, the light spot is focused on the quantum chip.

[0174] Specifically, this embodiment involves the movement of the third-direction adjuster 1063 and the coupling head 1020 so that, as observed from the microscope 1030, the light spot is focused on the quantum chip 2000. When observing the quantum chip 2000, it is often desirable to be able to accurately focus the light spot on the quantum chip 2000 in order to better illuminate the qubit unit. This can ensure that the intensity and shape of the light spot achieve the best effect on the qubit unit, thereby enabling more accurate and stable quantum operations and measurements. The third-direction adjuster is typically used to move the coupling head 1020 in the depth direction. By adjusting the third-direction adjuster 1063, the coupling head 1020 can be aligned with the quantum chip in the depth direction.

[0175] The advantage of this embodiment is that by adjusting the third-direction adjuster 1063, the light spot can be focused on the quantum chip 2000 so that the details and structure of the quantum chip 2000 can be observed from the microscope 1030.

[0176] In one embodiment, referring to Figure 2 , the coupling head 1020 is located on the first displacement stage 1060. The first displacement stage 1060 includes a first-direction adjuster 1061 and a second-direction adjuster 1062. The first direction is perpendicular to the second direction. The first direction is parallel to the quantum chip. The second direction is parallel to the quantum chip. In this embodiment, step 550 includes: moving the coupling head in the first direction through the first-direction adjuster and moving the coupling head in the second direction through the second-direction adjuster so that, as observed from the microscope, the distance between the light spot and the Josephson junction to be measured is a first distance.

[0177] The advantage of this embodiment is that by simultaneously adjusting the first-direction adjuster 1061 and the second-direction adjuster 1062, fine-tuning of the coupling head 1020 in the horizontal and vertical directions can be achieved, so that the distance between the light spot and the Josephson junction to be measured is the first distance, and thus impedance adjustment can be performed at the precise first distance.

[0178] In one embodiment, referring to Figure 6 , step 550 includes:

[0179] Step 610, obtaining an observation screenshot of the quantum chip by the microscope;

[0180] Step 620, in the observation screenshot, obtaining the first screenshot coordinates of the Josephson junction to be measured and obtaining the second screenshot coordinates of the light spot;

[0181] Step 630: Based on the correspondence between the screenshot coordinates and the actual coordinates, determine the first actual coordinate of the Josephson junction to be measured based on the first screenshot coordinate, and determine the second actual coordinate of the light spot based on the second screenshot coordinate.

[0182] Step 640: Based on the first actual coordinate and the first distance, determine the target actual focusing coordinate.

[0183] Step 650: Based on the second actual coordinate and the target actual focusing coordinate, calculate the first actual moving distance of the light spot in the first direction and the second actual moving distance of the light spot in the second direction.

[0184] Step 660: Based on the first actual moving distance of the light spot, drive the first-direction regulator to move the coupling head in the first direction, and based on the second actual moving distance of the light spot, drive the second-direction regulator to move the coupling head in the second direction.

[0185] In step 610, the observed screenshot refers to the image of the quantum chip observed from the microscope 1030. As Figure 7 shown, the observed screenshot contains multiple Josephson junctions of the quantum chip ( Figure 7 shows 8 Josephson junctions), and the multiple Josephson junctions include the Josephson junction to be measured. The observed screenshot also contains the light spot formed by the laser on the quantum chip.

[0186] In one embodiment, the setting of the acquisition period of the observed screenshot includes but is not limited to the following methods:

[0187] (1) Immediately obtain the observed screenshot after observing from the microscope that a light spot is formed on the quantum chip.

[0188] (2) Obtain the observed screenshot after observing from the microscope that a light spot is formed on the quantum chip and after a predetermined waiting time has passed.

[0189] In one embodiment, the acquisition method of the observed screenshot includes but is not limited to the following methods:

[0190] (1) Take a screenshot of the quantum chip observed by the microscope through the host computer to obtain the observed screenshot.

[0191] (2) Install a screenshot tool in the microscope. For example, the screenshot tool takes a screenshot of the quantum chip observed by the microscope and uploads the observed screenshot to the host computer.

[0192] In step 620, the first screenshot coordinate indicates the relative position of the Josephson junction to be measured in the observed screenshot. The second screenshot coordinate indicates the relative position of the light spot in the observed screenshot.

[0193] In one embodiment, the acquisition methods of the first screenshot coordinate and the second screenshot coordinate include but are not limited to the following methods:

[0194] (1) Establish a rectangular coordinate system based on the observation screenshot, map the Josephson junction to be measured and the light spot in the observation screenshot in the rectangular coordinate system, and obtain the first screenshot coordinate and the second screenshot coordinate.

[0195] (2) Input the observation screenshot into an image processing model to detect the first screenshot coordinate of the Josephson junction to be measured and the second screenshot coordinate of the light spot.

[0196] In an example, as Figure 8 shown, establish a rectangular coordinate system, map the Josephson junction to be measured and the light spot in the observation screenshot in the rectangular coordinate system, and the obtained first screenshot coordinate is (8, 6), and the second screenshot coordinate is (8.5, 7).

[0197] In step 630, since both the first screenshot coordinate and the second screenshot coordinate are relative coordinates rather than actual positions, it is necessary to use the correspondence between the screenshot coordinate and the actual coordinate to obtain the actual coordinate. The correspondence between the screenshot coordinate and the actual coordinate can be a coordinate table or a coordinate function. For example, based on the screenshot coordinate, query the coordinate table to obtain the actual coordinate. Or, input the screenshot coordinate into the coordinate function to obtain the mapped actual coordinate.

[0198] In an example, as Figure 9 shown, the correspondence between the screenshot coordinate and the actual coordinate is a coordinate table. The left column of this coordinate table is the screenshot coordinate, and the right column is the actual coordinate corresponding to the screenshot coordinate. The screenshot coordinate (2, 3) corresponds to the actual coordinate (1, 1). The screenshot coordinate (2, 6) corresponds to the actual coordinate (1, 2). The screenshot coordinate (4, 3) corresponds to the actual coordinate (2, 1). The screenshot coordinate (4, 6) corresponds to the actual coordinate (2, 2). The screenshot coordinate (6, 3) corresponds to the actual coordinate (3, 1). The screenshot coordinate (6, 6) corresponds to the actual coordinate (3, 2). The screenshot coordinate (8, 3) corresponds to the actual coordinate (4, 1). The screenshot coordinate (8, 6) corresponds to the actual coordinate (4, 2). The screenshot coordinate (8.5, 7) corresponds to the actual coordinate (4.25, 2.33). It can be understood that Figure 9 shown in the coordinate table only shows the correspondence between 9 screenshot coordinates and the actual coordinates, but in actual situations, it is not limited to these.

[0199] In this example, based on the first screenshot coordinate being (8, 6), the first actual coordinate is obtained as (4, 2). Based on the second screenshot coordinate being (8.5, 7), the second actual coordinate is obtained as (4.25, 2.33).

[0200] In step 640, the target actual focusing coordinate refers to the coordinate corresponding to the first distance between the light spot and the Josephson junction to be measured.

[0201] Specifically, the light spot and the Josephson junction to be measured can be separated by a first distance in the first direction, or by a first distance in the second direction. The light spot and the Josephson junction to be measured can also be separated by a first distance in the direction of the angle between the first direction and the second direction.

[0202] In one example, assume that the first distance is 5 μm. Among them, 5 μm is converted into a coordinate interval of 0.5. Based on the first actual coordinate being (4, 2) and the first distance being 5 μm, the target actual focusing coordinate is determined to be (4.5, 2). In this way, the light spot and the Josephson junction to be measured are separated by 5 μm in the first direction. In another example, assume that the first distance is 5 μm. Based on the first actual coordinate being (4, 2) and the first distance being 5 μm, the target actual focusing coordinate is determined to be (4, 2.5). In this way, the light spot and the Josephson junction to be measured are separated by 5 μm in the second direction. In another example, assume that the first distance is 5 μm. Based on the first actual coordinate being (4, 2) and the first distance being 5 μm, the target actual focusing coordinate is determined to be (4.3, 2.4). In this way, the light spot and the Josephson junction to be measured are separated by 3 μm in the first direction and 4 μm in the second direction, so that the light spot and the Josephson junction to be measured are separated by 5 μm in total.

[0203] In step 650, the actual moving distance of the first light spot is the coordinate difference between the second actual coordinate and the target actual focusing coordinate in the first direction. The actual moving distance of the second light spot is the coordinate difference between the second actual coordinate and the target actual focusing coordinate in the second direction. In one example, the second actual coordinate is (4.25, 2.33), and the target actual focusing coordinate is (4, 2.5). The coordinate interval in the first direction is -0.25, so the actual moving distance of the first light spot is -2.5 μm. The coordinate interval in the second direction is 0.17, so the actual moving distance of the second light spot is 1.7 μm. In another example, the second actual coordinate is (4.25, 2.33), and the target actual focusing coordinate is (4.3, 2.4). The coordinate interval in the first direction is 0.05, so the actual moving distance of the first light spot is 0.5 μm. The coordinate interval in the second direction is 0.07, so the actual moving distance of the second light spot is 0.7 μm.

[0204] After determining the actual moving distance of the first light spot and the actual moving distance of the second light spot, in step 660, based on the actual moving distance of the first light spot, drive the first-direction regulator to move the coupling head in the first direction, and based on the actual moving distance of the second light spot, drive the second-direction regulator to move the coupling head in the second direction. As Figure 10As shown, assume that the second actual coordinate is (4.25, 2.33), and the target actual focusing coordinate is (4.5, 2). After driving the first-direction regulator to move the coupling head 2.5 μm in the first direction and driving the second-direction regulator to move the coupling head -0.33 μm in the second direction, the light spot moves from the position of the dashed circle to the position of the solid circle. Observed from the microscope, the light spot is at a first distance of 5 μm from the Josephson junction to be measured in the first direction.

[0205] The advantage of the embodiment of steps 610 - 660 is that automatic position adjustment is achieved based on the observed screenshots, improving the automation degree of impedance adjustment. It has high universality and practicality.

[0206] In step 560, the impedance sensor is pressed against the Josephson junction to be measured to sense the impedance of the Josephson junction to be measured while adjusting the light spot, and stop adjusting the light spot until the sensed impedance reaches a predetermined impedance.

[0207] Specifically, the greater the power of the laser, the greater the impedance of the Josephson junction to be measured. The smaller the distance between the light spot and the Josephson junction to be measured, the greater the impedance of the Josephson junction to be measured. Therefore, adjusting the light spot can be adjusting the power of the laser, or adjusting the distance between the light spot and the Josephson junction to be measured. Adjusting the light spot can also be adjusting the power of the laser while adjusting the distance between the light spot and the Josephson junction to be measured.

[0208] In one embodiment, the laser has the lowest power. Refer to Figure 11 , step 560 includes:

[0209] Step 1110, initialize the target laser power to the lowest power;

[0210] Step 1120, execute the first process. The first process includes: opening the baffle of the laser. If the sensed impedance gradually increases within a predetermined time period and reaches a stable impedance, determine whether the stable impedance reaches the predetermined impedance. If not, close the baffle of the laser, increase the target laser power by a predetermined power step, and repeat the first process until the stable impedance reaches the predetermined impedance.

[0211] In step 1110, the target laser power is a variable used to indicate the current power of the laser. The lowest power is a constant used to indicate the minimum power of the laser. For example, the lowest power of the laser is 50 mW.

[0212] In step 1120, the baffle of the laser is opened, so that the laser emitted by the laser forms a light spot on the quantum chip, and the impedance of the Josephson junction to be measured will increase to a stable impedance under the influence of the light spot. Closing the baffle of the laser can block the laser emitted by the laser, so as to cause adverse effects on the Josephson junction to be measured when a predetermined power step is added to the target laser power. The predetermined duration refers to a preset duration threshold, such as 1 second, 2 seconds, etc. The stable impedance refers to the impedance of the Josephson junction to be measured after being irradiated by the laser emitted by the laser, and the impedance of the Josephson junction to be measured increases to a relatively stable impedance value that will not change. The predetermined impedance refers to a preset impedance threshold. When the impedance of the Josephson junction to be measured reaches the predetermined impedance, the first process ends. The predetermined power step refers to the amplitude of the power increase set in advance, such as 50 mW, 100 mW, etc. The first process is repeatedly executed, aiming to irradiate the Josephson junction to be measured based on the target laser power after increasing the predetermined power step, so that the sensed stable impedance reaches the predetermined impedance.

[0213] In one example, the target laser power is initialized to 50 mW, and the repeated execution of the first process specifically includes:

[0214] (1) Open the baffle of the laser. If the impedance sensed by the impedance sensor gradually increases within the predetermined duration and reaches the stable impedance, determine whether the stable impedance reaches the predetermined impedance;

[0215] (2) If the stable impedance does not reach the predetermined impedance, close the baffle of the laser; increase the target laser power by 50 mW; return to step (1);

[0216] (3) If the stable impedance has reached the predetermined impedance, turn off the laser, lift the impedance sensor, and take out the quantum chip.

[0217] The advantage of the embodiment of steps 1110 - 1120 is that by gradually increasing the target laser power to achieve impedance growth, the error rate can be reduced to avoid interference or damage to the quantum chip caused by too high power. It can also help the operator better understand the operation steps and reduce the possibility of operation errors and operation failures. It should be noted that in addition to using the baffle of the laser to block the laser, the laser can also be directly turned off to turn off the laser. However, it usually takes some time for the laser to stabilize after being turned on, resulting in a longer test cycle. Therefore, using the baffle in this embodiment can also improve the adjustment efficiency.

[0218] In another embodiment, the laser also has a maximum power. Refer to Figure 12 , after executing the first process, step 560 further includes:

[0219] Step 1210, initialize the target distance to the first distance;

[0220] Step 1220: Execute the second process, which includes: if the stable impedance has not reached the predetermined impedance after the laser has reached its maximum power, reduce the target distance by a predetermined distance step, and change the target laser power to the minimum power; move the coupling head in a direction parallel to the quantum chip so that, as observed through the microscope, the distance between the light spot and the Josephson junction to be measured is the target distance; execute the first process; repeat the second process until the stable impedance reaches the predetermined impedance.

[0221] In step 1210, the target distance is a variable used to indicate the current distance between the light spot and the Josephson junction to be measured. The maximum power is a constant used to indicate the maximum power of the laser. For example, the maximum power of the laser is 700 mW. Combining the foregoing, the power of the laser is 50 mW - 700 mW.

[0222] In step 1220, if the stable impedance has not reached the predetermined impedance after the laser has reached its maximum power, it means that at the current distance between the light spot and the Josephson junction to be measured, it is no longer possible to adjust the power of the laser to make the stable impedance reach the predetermined impedance. Therefore, it is necessary to reduce the distance between the light spot and the Josephson junction to be measured. Specifically, in this embodiment, on the premise that the target distance is initialized to the first distance, the target distance is reduced by a predetermined distance step. Then, move the coupling head in a direction parallel to the quantum chip so that, as observed through the microscope, the distance between the light spot and the Josephson junction to be measured is the target distance. The predetermined distance step refers to a pre-set distance threshold, such as 2 μm, 3 μm, etc. While reducing the target distance by the predetermined distance step, the target laser power is also changed to the minimum power. In this way, during impedance adjustment, the power of the laser can be gradually increased from the minimum power to the maximum power to achieve gradual impedance adjustment.

[0223] In an example, the target distance is initialized to 5 μm. After executing the first process, the specific steps for repeating the second process include:

[0224] (1) If the stable impedance has not reached the predetermined impedance after the laser has reached 700 mW, reduce the target distance by 2 μm and change the target laser power to 50 mW;

[0225] (2) Move the coupling head in a direction parallel to the quantum chip so that, as observed through the microscope, the distance between the light spot and the Josephson junction to be measured is 3 μm;

[0226] (3) Open the baffle of the laser. If the impedance sensed by the impedance sensor gradually increases within a predetermined time period and reaches the stable impedance, determine whether the stable impedance reaches the predetermined impedance;

[0227] (4) If the stable impedance has not reached the predetermined impedance and if the laser has not reached 700 mW, close the baffle of the laser; increase the target laser power by 50 mW; then repeat step (3);

[0228] (5) If the stable impedance does not reach the predetermined impedance and if the laser does not reach 700 mW, return to step (1).

[0229] (6) If the stable impedance has reached the predetermined impedance, turn off the laser, lift the impedance sensor, and take out the quantum chip.

[0230] The advantage of the embodiment of steps 1210 - 1220 is that by gradually reducing the distance between the light spot and the Josephson junction to be measured to achieve impedance growth, the error rate can be reduced to avoid interference or damage to the quantum chip caused by the light spot at too close a distance.

[0231] Next, refer to Figure 13 for a detailed exemplary description of the implementation details of the method for adjusting the impedance of the Josephson junction of the quantum chip according to the embodiments of the present disclosure.

[0232] As Figure 13 shown, the method for adjusting the impedance of the Josephson junction of the quantum chip according to the embodiments of the present disclosure includes:

[0233] (1) Start.

[0234] (2) Move the microscope in the first direction through the fourth - direction regulator and move the microscope in the second direction through the fifth - direction regulator so that the microscope is aligned with the quantum chip. For example, refer to Figure 1 , Figure 2 , and Figure 3 to adjust the quantum chip 2000 and the microscope 1030 to an appropriate height, adjust the working distance of the microscope 1030 to ensure that the structure of the quantum chip 2000 can be clearly seen at the highest magnification. For example, first fix the position of the quantum chip 2000; secondly, through the fourth - direction regulator 1131 and the fifth - direction regulator 1132 on the top seat 1130, adjust the horizontal position of the microscope 1030 so that it is exactly above the quantum chip 2000. Insert the probe 1041 into the capacitance region of the Josephson junction to be measured, and the probe 1041 is connected to the source meter, and the source meter reads the impedance value in real - time. As long as the probe 1041 is inserted into the capacitance of the Josephson junction to be measured, the specific position has no effect on the measured impedance value. The measured impedance value is only affected by the light spot focused on the quantum chip 2000.

[0235] (3) By adjusting the length of the telescopic rod, make it possible to observe the quantum chip under the maximum magnification of the microscope. For example, refer to Figure 3 and adjust the height through the telescopic rod 1123 to ensure that the chip structure can be clearly seen at the highest magnification.

[0236] (4) Move the coupling head in the first direction through the first direction regulator and move the coupling head in the second direction through the second direction regulator, so that from the microscope observation, the light spot is formed in the area outside the qubit unit in the quantum chip in the microscope field of view. For example, referring to Figure 1 、 Figure 2 and Figure 3 , by adjusting the first direction regulator 1061 and the second direction regulator 1062 on the first displacement stage 1060, the position of the laser irradiation on the chip is adjusted so that the light spot appears in the microscope field of view and stays in the blank area without qubit unit structure.

[0237] (5) Move the coupling head in the third direction through the third direction regulator, so that from the microscope observation, the light spot is focused on the quantum chip. Adjust the vertical height of the coupling head 1020. For example, referring to Figure 1 、 Figure 2 and Figure 3 , it is to adjust the third direction regulator 1063 of the first displacement stage 1060 to focus the light spot of the laser on the quantum chip 2000.

[0238] (6) Move the coupling head in the first direction through the first direction regulator and move the coupling head in the second direction through the second direction regulator, so that from the microscope observation, the distance between the light spot and the Josephson junction to be measured is the first distance. For example, referring to Figure 1 、 Figure 2 and Figure 3 , by adjusting the first direction regulator 1061 and the second direction regulator 1062 of the first displacement stage 1060, the light spot is adjusted to a position 5 μm near the Josephson junction to be measured (the Josephson junction to be measured can be seen through the microscope 1030, and 5 μm can also be measured). Turn off the Shuttle of the laser (baffle, do not directly turn off the laser power because it needs to be stabilized again every time the laser is restarted). Specifically, the upper computer 1150 can save the observation screenshot observed by the microscope, and calculate the first actual coordinate of the Josephson junction to be measured and the second actual coordinate of the light spot according to the positions of the Josephson junction to be measured and the light spot in the observation screenshot. Calculate the target actual focusing coordinate according to 5 μm and the first actual coordinate. According to the target actual focusing coordinate, calculate the first actual moving distance and the second actual moving distance that the coupling head 1020 needs to move. Then automatically drive the first direction regulator 1061 and the second direction regulator 1062 to move.

[0239] (7) Initialize the target laser power to the lowest power. For example, after the laser 1010 is powered on and stabilized for 10 minutes, the power is adjusted to the lowest power, and the lowest output power is 50 mW.

[0240] (8) Initialize the target distance to the first distance. For example, initialize the target distance to 5 μm.

[0241] (9) Open the baffle of the laser. If the sensed impedance gradually increases within a predetermined time duration and reaches a stable impedance.

[0242] (10) Determine whether the stable impedance reaches a predetermined impedance. If not, proceed to step (11). If so, proceed to step (14).

[0243] (11) Determine whether the laser reaches the maximum power. If not, proceed to step (12). If so, proceed to step (13).

[0244] (12) Close the baffle of the laser, and increase the target laser power by a predetermined power step. For example, adjust the power of the laser to 100 mW. Return to step (9).

[0245] (13) Close the baffle of the laser, reduce the target distance by a predetermined distance step, and change the target laser power to the minimum power; move the coupling head in a direction parallel to the quantum chip so that, as observed from the microscope, the distance between the light spot and the Josephson junction to be measured is the target distance. Return to step (9).

[0246] (14) End. Specifically, turn off the laser, lift the impedance sensor, and take out the quantum chip.

[0247] The advantages of this embodiment include, but are not limited to, being able to separately adjust the impedance of the Josephson junction to be measured. By selecting a transparent double-polished sapphire chip substrate and coupling the coupling head for laser irradiation on the quantum chip, the microscope for observing the position of the light spot, and the impedance sensor for measuring impedance in a unified device, real-time laser irradiation and real-time measurement are achieved. The coupling head turns the laser of the laser into a light spot and hits the back of the quantum chip. Since the double-polished sapphire chip substrate is transparent, a microscope is placed on the other side of the quantum chip, and the microscope can observe the position of the light spot. On the other hand, the impedance sensor is tightly clamped on the quantum chip to measure the impedance in real time. In this way, during the impedance adjustment process, when the impedance of the Josephson junction to be measured has not reached the predetermined impedance, the distance between the light spot and the Josephson junction and the power of the laser can be observed through the microscope and adjusted in real time to gradually reach the predetermined impedance. The whole process is carried out in real time and continuously, without going through isolated and repeated processes such as measuring after laser irradiation and then measuring again after laser irradiation, improving the adjustment efficiency and reducing the adjustment cost.

[0248] The embodiments of the present disclosure can be applied to various scenarios such as quantum chip testing and superconducting quantum chip manufacturing.

[0249] It should be understood that in the description of the embodiments of the present disclosure, the meaning of multiple (or plural) is more than two, and understandings such as greater than, less than, exceeding, etc. do not include the present number, and understandings such as above, below, within, etc. include the present number.

[0250] In the description of the embodiments of the present disclosure, unless otherwise specified, " / " means "or". For example, A / B may mean A or B; herein, "and / or" is merely a description of the association relationship between associated objects, indicating that there can be three relationships. For example, A and / or B may mean: A exists alone, A and B exist simultaneously, and B exists alone.

[0251] In several embodiments provided by the present disclosure, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection between each other can be through some interfaces, and the indirect coupling or communication connection of devices or units can be in electrical, mechanical, or other forms.

[0252] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0253] In addition, each functional unit in various embodiments of the present disclosure can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

[0254] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present disclosure, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods in various embodiments of the present disclosure. The aforementioned storage medium includes: USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs, etc., which can store program codes.

[0255] It should also be understood that the various embodiments provided by the embodiments of the present disclosure can be combined arbitrarily to achieve different technical effects.

[0256] The above is a specific description of the embodiments of the present disclosure, but the present disclosure is not limited to the above embodiments. Those skilled in the art can also make various equivalent deformations or substitutions without departing from the spirit of the present disclosure, and these equivalent deformations or substitutions are all included within the scope defined by the claims of the present disclosure.

Claims

1. An impedance adjustment device for Josephson junctions of a quantum chip, characterized in that, it includes: a laser; a coupling head for focusing the laser light emitted by the laser to form a light spot on the transparent quantum chip; an impedance sensor pressed against the Josephson junction to be measured on the quantum chip, for sensing the impedance of the Josephson junction to be measured while adjusting the light spot, and stopping adjusting the light spot until the sensed impedance reaches a predetermined impedance.

2. The impedance adjustment device according to claim 1, characterized in that, the transparency is full transparency; the impedance adjustment device further includes: a microscope located on opposite sides of the quantum chip from the coupling head, for observing the light spot transmitted from the quantum chip while adjusting the light spot.

3. The impedance adjustment device according to claim 1, characterized in that, the impedance adjustment device further includes a base and a first displacement stage, the first displacement stage is installed on the base to fix the coupling head, and the first displacement stage is used to move the coupling head to adjust the position of the light spot on the quantum chip.

4. The impedance adjustment device according to claim 3, characterized in that, the first displacement stage includes a first direction regulator, a second direction regulator, and a third direction regulator, the first direction, the second direction, and the third direction are perpendicular to each other in pairs, the third direction regulator is used for focusing to form the light spot on the quantum chip, and the first direction regulator and the second direction regulator are used to adjust the position of the light spot.

5. The impedance adjustment device according to claim 3, characterized in that, the base has a first connection structure, the first displacement stage has a second connection structure, and the first connection structure cooperates with the second connection structure to install the first displacement stage on the base.

6. The impedance adjustment device according to claim 1, characterized in that, the impedance adjustment device includes a fixture base and a clamping arm extending from the fixture base, the clamping arm presses against the quantum chip on the opposite side of the coupling head to fix the quantum chip.

7. The impedance adjustment device according to claim 6, characterized in that, the impedance adjustment device further includes a base and a second displacement stage, the second displacement stage is installed on the base to fix the fixture base, and the second displacement stage is used to move the clamping arm to clamp the quantum chip.

8. The impedance adjustment device according to claim 7, characterized in that, the base has a third connection structure, the second displacement stage has a fourth connection structure, and the third connection structure cooperates with the fourth connection structure to install the second displacement stage on the base.

9. The impedance adjustment device according to claim 1, characterized in that, the impedance adjustment device further includes a support structure and an impedance sensor base installed on the support structure, the impedance sensor is installed in the impedance sensor base and extends towards the direction of the Josephson junction to be measured to press against the position of the Josephson junction to be measured.

10. The impedance adjustment device according to claim 3, It is characterized in that the impedance adjustment device further includes a support rod extending from the base towards the quantum chip and a top seat integrally connected to the support rod, and the microscope is suspended from the top seat.

11. The impedance adjustment device according to claim 10 It is characterized in that the support rod includes a first section, a second section, and a telescopic rod located between the first section and the second section. The relative distance between the microscope and the quantum chip in the third direction is adjusted by adjusting the length of the telescopic rod.

12. The impedance adjustment device according to claim 11 It is characterized in that the top seat is provided with a fourth-direction adjuster and a fifth-direction adjuster. The fourth-direction adjuster is used to move the microscope in the first direction, and the fifth-direction adjuster is used to move the microscope in the second direction so that the microscope is aligned with the quantum chip in the third direction, where the first direction, the second direction, and the third direction are perpendicular to each other in pairs.

13. A method for adjusting the impedance of a Josephson junction of a quantum chip It is characterized in that it is used for an impedance adjustment device, and the impedance adjustment device includes a laser, a coupling head, a microscope, and an impedance sensor. The quantum chip is a transparent quantum chip. The method includes: focusing the laser emitted by the laser through the coupling head to form a light spot on the quantum chip as observed from the microscope; moving the coupling head in a direction parallel to the quantum chip so that the distance between the light spot and the Josephson junction to be measured is a first distance as observed from the microscope; pressing the impedance sensor against the Josephson junction to be measured to sense the impedance of the Josephson junction to be measured while adjusting the light spot until the sensed impedance reaches a predetermined impedance, and then stop adjusting the light spot.

14. The method according to claim 13 It is characterized in that the laser has a minimum power; the step of sensing the impedance of the Josephson junction to be measured while adjusting the light spot until the sensed impedance reaches a predetermined impedance and then stop adjusting the light spot includes: initializing the target laser power to the minimum power; executing a first process, the first process includes: opening the shutter of the laser. If the sensed impedance gradually increases within a predetermined time period and reaches a stable impedance, determine whether the stable impedance reaches the predetermined impedance. If not, close the shutter of the laser, increase the target laser power by a predetermined power step, and repeat the first process until the stable impedance reaches the predetermined impedance.

15. The method according to claim 14 It is characterized in that the laser also has a maximum power. After executing the first process, the method further includes: initializing the target distance to the first distance; Execute the second process, where the second process includes: if the stable impedance has not reached the predetermined impedance after the laser has reached the maximum power, reduce the target distance by the predetermined distance step and change the target laser power to the minimum power; move the coupling head in a direction parallel to the quantum chip so that, as observed from the microscope, the distance between the light spot and the Josephson junction to be measured is the target distance; execute the first process; repeat the second process until the stable impedance reaches the predetermined impedance.

16. The method according to claim 13, wherein, the coupling head is located on a first displacement stage, and the first displacement stage includes a first direction adjuster and a second direction adjuster, the first direction is perpendicular to the second direction, the first direction is parallel to the quantum chip, and the second direction is parallel to the quantum chip; the moving the coupling head in a direction parallel to the quantum chip so that, as observed from the microscope, the distance between the light spot and the Josephson junction to be measured is the first distance includes: moving the coupling head in the first direction by the first direction adjuster and moving the coupling head in the second direction by the second direction adjuster so that, as observed from the microscope, the distance between the light spot and the Josephson junction to be measured is the first distance.

17. The method according to claim 16, wherein, the moving the coupling head in the first direction by the first direction adjuster and moving the coupling head in the second direction by the second direction adjuster so that, as observed from the microscope, the distance between the light spot and the Josephson junction to be measured is the first distance includes: acquiring an observation screenshot of the quantum chip by the microscope; in the observation screenshot, acquiring the first screenshot coordinates of the Josephson junction to be measured and acquiring the second screenshot coordinates of the light spot; using the correspondence between the screenshot coordinates and the actual coordinates, determining the first actual coordinates of the Josephson junction to be measured based on the first screenshot coordinates and determining the second actual coordinates of the light spot based on the second screenshot coordinates; determining the target actual focusing coordinates based on the first actual coordinates and the first distance; calculating the first actual moving distance of the light spot in the first direction and the second actual moving distance of the light spot in the second direction based on the second actual coordinates and the target actual focusing coordinates; driving the first direction adjuster to move the coupling head in the first direction based on the first actual moving distance of the light spot and driving the second direction adjuster to move the coupling head in the second direction based on the second actual moving distance of the light spot.

18. The method according to claim 16, wherein, the first displacement stage further includes a third direction adjuster, the third direction is perpendicular to the first direction, and the third direction is perpendicular to the second direction; the focusing the laser emitted by the laser by the coupling head to form a light spot on the quantum chip as observed from the microscope includes: Move the coupling head in the third direction through the third direction adjuster so that, as observed from the microscope, the light spot is focused on the quantum chip.

19. The method according to claim 13, wherein, the impedance adjustment device further includes a top seat to which the microscope is fixed, the top seat includes a fourth direction adjuster and a fifth direction adjuster, a first direction is perpendicular to a second direction, the first direction is parallel to the quantum chip, and the second direction is parallel to the quantum chip; before focusing the laser light emitted by the laser through the coupling head so that, as observed from the microscope, a light spot is formed on the quantum chip, the method further includes: moving the microscope in the first direction through the fourth direction adjuster and moving the microscope in the second direction through the fifth direction adjuster so that the microscope is aligned with the quantum chip.

20. The method according to claim 19, wherein, the impedance adjustment device further includes a base and a support rod extending from the base towards the quantum chip, the support rod is integrally connected to the top seat, and the support rod includes a first section, a second section, and a telescopic rod located between the first section and the second section; after moving the microscope in the first direction through the fourth direction adjuster and moving the microscope in the second direction through the fifth direction adjuster so that the microscope is aligned with the quantum chip, the method further includes: adjusting the length of the telescopic rod so that the quantum chip can be observed from the microscope at the maximum magnification of the microscope.

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