Noise reduction circuit and corresponding method for quantum computers

Abstract

To provide methods, devices, systems, or a computer program products for providing a signal to an electrode of a quantum computer.SOLUTION: In an exemplary embodiment, a system includes a noise reduction circuitry having a signal generator, a gain stage, and a filter stage. The signal generator may be comprised of a plurality of voltage sources. A controller causes the signal generator to generate a signal. The signal is provided to an electrode via the noise mitigation circuitry to cause at least a part of the system to perform a function.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Cross - Reference to Related Applications

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 145,039, filed on February 3, 2021, the entire content of which is incorporated herein by reference for all purposes.

[0002]

[0002] Various embodiments relate to apparatuses, systems, and methods for reducing signal noise in quantum computers. For example, some exemplary embodiments relate to the use of a signal generator including a dual voltage source and / or filtering including active and passive filters for reducing the noise of signals applied to the electrodes of an ion trap.

Background Art

[0003]

[0003] In various scenarios, a quantum computing system having electrical components can be configured to perform multiple functions, and different functions can have different tolerances. These tolerances can include the amount of noise present in the signals applied to various electrical components and / or the amount of heat that can be applied to the electrical components by the signals. For example, an ion trap can use a combination of an electric field and a magnetic field to trap multiple ions within a potential well. Various functions can be performed to move ions through a part of the ion trap in a specific way and / or to include them in a specific part of the ion trap. These various functions can have different noise tolerances of the signals used to generate the combination of the electric field and the magnetic field and / or different heat tolerances of the electrical components. Further, the electrical circuit used to generate the signal can include circuit components that add heat to the ions. Many of the deficiencies of such conventional ion traps have been solved by developing structured solutions in accordance with embodiments of the present invention through efforts, ingenuity, and implementation of innovations, and many examples thereof are described in detail herein.

Summary of the Invention

[0004]

[0004] Exemplary embodiments include systems, methods, apparatus, and computer program products for quantum computers, specifically, noise reduction for quantum computers. [Means for solving the problem]

[0005]

[0005] Various embodiments provide a system for providing signals to electrodes in an ion trap of a quantum computer. In various embodiments, the system may consist of a signal generator, a gain stage, a filter stage, and / or a transducer. In various embodiments, the signal generator may be configured to generate a first signal, the first signal including a frequency sweep. In various embodiments, the gain stage may be configured to amplify the signal, and the input to the gain stage is connected to the output of the signal generator. In various embodiments, the filter stage may be configured to filter the signal, and the input to the filter stage is connected to the output of the gain stage. The transducer may be further configured to measure the response at the output of the filter stage in response to the first signal. The signal generator may be further configured to generate a second signal, the second signal being pre-distorted with a determined pre-distorted waveform based on the measured response. In various embodiments, the electrodes in the ion trap are configured to receive the second signal.

[0006]

[0006] In various embodiments, the filter stage includes an active filter and a passive filter.

[0007] In various embodiments, the signal generator includes a first digital-to-analog converter and a second digital-to-analog converter.

[0007]

[0008] In various embodiments, the second digital-to-analog converter is configured to provide a DC offset voltage.

[0009] In various embodiments, the first digital-to-analog converter is configured to provide a pre-distorted second signal.

[0008]

[0010] In various embodiments, the output of a signal generator connected to the input of a gain stage is connected via a switch, which switches between connection to the input of the gain stage and connection to a converter.

[0009]

[0011] In various embodiments, the filter stage includes a low-pass filter.

[0012] In various embodiments, the filter stage includes a filter having a Butterworth response.

[0010]

[0013] In various embodiments, an ion trap is configured to have a plurality of ions trapped within it, at least some of which are used as qubits in a quantum computer.

[0011]

[0014] Various embodiments provide a method for pre-distorting a signal generated by a signal generator of a quantum computer. In various embodiments, the method includes the step of having a controller cause the signal generator to generate a first signal, the first signal including a frequency sweep over a plurality of frequencies. The method further includes the step of having the first signal provided to a noise reduction circuit, the noise reduction circuit including a filter stage, the filter stage configured to filter the first signal according to a filter response to provide a filtered signal. The method further includes the steps of measuring the filtered signal using a transducer and causing the signal generator to generate a second signal, the second signal being pre-distorted based on the measurement of the filtered signal. The method further includes the step of having the second signal provided to electrodes of an ion trap of a quantum computer.

[0012]

[0015] Various embodiments provide a method for providing a signal from a signal generator of a quantum computer. In various embodiments, the method includes the step of setting a first switch to a first position by a controller, the first switch including an input, and at least a first output and a second output, the first position corresponding to a first output, the second position corresponding to a second output, the first output of the first switch connected to a transducer, the second output of the first switch connected to the input of a gain stage, the gain stage including an output, the output of the gain stage connected to the input of a filter stage, and the output of the filter stage connected to a transducer. The method further includes the step of causing a signal generator to generate and provide a first signal to the first switch by the controller, the first signal including a frequency sweep or a pulse. The method further includes measuring a first response from the generation of the first signal in the transducer. The method further includes setting the first switch to a second position. The method further includes the step of causing a signal generator to generate a second signal and provide it to a first switch in a second position, the second signal including a frequency sweep or a pulse. The method further includes measuring a second response from the generation of the second signal in a transducer. The method further includes determining a frequency response based on the measured values ​​of the first and second responses. The method further includes causing a signal generator to generate a third signal based on the frequency response, the third signal being pre-distorted based on the frequency response. The method further includes providing the third signal to electrodes of an ion trap in a quantum computer.

[0013]

[0016] Various embodiments provide a method for providing a signal from a quantum computer signal generator for time-domain reflectometry measurement. In various embodiments, the method includes the step of setting a first switch to a first position, wherein the first switch includes an input to the first switch, as well as at least a first output and a second output of the first switch, where the first position of the first switch corresponds to the first output of the first switch, and the second position of the first switch corresponds to the second output of the first switch. The method further includes the step of setting a second switch to a first position, wherein the second switch includes at least a first input and a second input of the second switch, as well as an output of the second switch, where the first position of the second switch corresponds to the first input of the second switch, and the second position of the second switch corresponds to the second output of the second switch. In various embodiments, the first output of the first switch is connected to the first input of the second switch. In various embodiments, the second output of the first switch is connected to the input of a gain stage, the gain stage includes an output, the output of the gain stage is connected to the input of a filter stage, the output of the filter stage is connected to the second input of the second switch, and the output of the second switch is connected to an ion trap of a quantum computer. The method further includes the step of causing a signal generator to generate a first signal by a controller, the first signal including a pulse. The method further includes the step of measuring a first response from the generation of the first signal at the output of the second switch using a transducer, the measurement of the first response including a time-domain reflectivity measurement.

[0014]

[0017] Various embodiments provide a method for providing a signal from a quantum computer signal generator for time-domain reflectance measurements. In some embodiments, the method includes the step of setting a first switch to a second position of the first switch, wherein the first switch includes an input to the first switch, as well as at least a first output and a second output of the first switch, where the first position of the first switch corresponds to the first output of the first switch, and the second position of the first switch corresponds to the second output of the first switch. The method further includes the step of setting a second switch to a second position of the second switch, wherein the second switch includes at least a first input and a second input of the second switch, as well as an output of the second switch, where the first position of the second switch corresponds to the first input of the second switch, and the second position of the second switch corresponds to the second output of the second switch. In various embodiments, the first output of the first switch is connected to the first input of the second switch. In various embodiments, the second output of the first switch is connected to the input of a gain stage, the gain stage includes an output, the output of the gain stage is connected to the input of a filter stage, the output of the filter stage is connected to the second input of the second switch, and the output of the second switch is connected to an ion trap of a quantum computer. The method further includes the step of causing a signal generator to generate a first signal by a controller, the first signal including a pulse. The method further includes the step of measuring a first response from the generation of the first signal at the output of the second switch using a transducer, the measurement of the first response including a time-domain reflectivity measurement.

[0015]

[0018] Various embodiments provide a method for providing a signal from a signal generator of a quantum computer for noise spectral density measurement. In various embodiments, the method includes the step of setting a first switch to a first position of the first switch, the first switch including an input to the first switch, as well as at least a first output and a second output of the first switch, the first position of the first switch corresponding to a first output of the first switch, and the second position of the first switch corresponding to a second output of the first switch. In various embodiments, the first output of the first switch is connected to a transducer. In various embodiments, the second output of the first switch is connected to the input of a gain stage, the gain stage including an output, the output of the gain stage is connected to the input of a filter stage, the output of the filter stage is connected to a second switch, the second switch including an input, as well as a first output and a second output, the first output of the second switch is connected to an ion trap of a quantum computer, and the second output of the second switch is connected to a transducer. The method further includes the step of causing a signal generator to generate a first signal using a controller, the first signal including a DC voltage. The method further includes the step of measuring a first response using a converter, the measurement of the first response including noise spectral density measurement.

[0016]

[0019] In various embodiments, the method further includes the step of measuring the noise spectral density of an electrode in an ion trap using a transducer, wherein the input to the transducer is connected to the output of a gain stage, and the input to the gain stage is connected to an electrode in an ion trap.

[0017]

[0020] In various embodiments, the electrode is configured to have a plurality of ions trapped therein, at least some of which are used as qubits in a quantum computer.

[0018]

[0021] Various embodiments provide a system for providing a signal to an electrode in an ion trap. In various embodiments, the system includes a signal generator comprising a waveform generator, a converter, and a switch. In various embodiments, the waveform generator is configured to generate a waveform signal. In various embodiments, the converter is a digital-to-analog converter and is configured to generate a DC signal. In various embodiments, the switch has a first input to the switch connected to the output of the waveform generator, a second input to the switch connected to the output of the converter, and an output to the switch. In various embodiments, the signal generator is configured to generate a coupled signal by moving the switch between the first and second inputs to couple the waveform signal and the DC signal at the output of the signal generator. The system further includes a gain stage configured to amplify the coupled signal, the input to the gain stage being connected to the output of the switch. The system further includes an ion trap connected to the output of the gain stage, the ion trap including at least one electrode, the at least one electrode being connected to the output of the gain stage.

[0019]

[0022] Various embodiments provide a system for providing a signal to an electrode in an ion trap, and in various embodiments, the system includes a signal generator configured to produce a first signal, the first signal including a frequency sweep. The system further includes a gain stage configured to amplify the first signal, the input to the gain stage connected to the output of the signal generator. The system further includes a filter stage configured to filter the first signal, the input to the filter stage connected to the output of the gain stage. The system further includes a transducer configured to measure a response at the output of the filter stage in response to the first signal. In various embodiments, the signal generator is further configured to produce a second signal, the second signal being pre-distorted based on the measured response of the first signal, and in various embodiments, the electrode in the ion trap is configured to receive the second signal.

[0020]

[0023] Various embodiments provide a system for providing a signal to an electrode in an ion trap, and in various embodiments, the system includes a signal generator configured to produce a first signal, the first signal including a frequency sweep. The system further includes a gain stage configured to amplify the first signal, the input to the gain stage connected to the output of the signal generator. The system further includes a filter stage configured to filter the first signal, the input to the filter stage connected to the output of the gain stage. The system further includes a sample stage, the input to the sample stage connected to the output of the filter stage. The system further includes a transducer configured to measure a response at the output of the sample stage in response to the first signal. In various embodiments, the signal generator is further configured to produce a second signal, the second signal being pre-distorted based on the measured response of the first signal, and in various embodiments, the electrode in the ion trap is configured to receive the second signal.

[0021]

[0024] Various embodiments provide a system for providing a signal to an electrode in an ion trap, in which various embodiments the system includes a signal generator configured to produce a first signal, the first signal including a frequency sweep. The system further includes a gain stage configured to amplify the first signal, the input to the gain stage connected to the output of the signal generator. The system further includes a filter stage configured to filter the first signal, the input to the filter stage connected to the output of the gain stage. The system further includes a transducer configured to measure a response at the output of the filter stage in response to the first signal. In the system, the signal generator is further configured to produce a second signal, the second signal being pre-distorted based on the measured response of the first signal. In various embodiments the electrode in the ion trap is configured to receive the second signal.

[0022]

[0025] Having described the present invention using general terminology, let us now refer to the attached drawings. The attached drawings are not necessarily drawn to a fixed scale.

Brief Description of the Drawings

[0023] [Figure 1]

[0026] Schematic diagrams of exemplary quantum computing systems according to various embodiments. [Figure 2]

[0027] Schematic diagrams of exemplary controllers of quantum computers according to various embodiments. [Figure 3]

[0028] Schematic diagrams of exemplary computing entities of a quantum computer system that can be used according to exemplary embodiments. [Figure 4]

[0029] Schematic diagrams of exemplary noise reduction circuits according to various embodiments. [Figure 5]

[0030] Schematic diagrams of another exemplary noise reduction circuit according to various embodiments. [Figure 6]

[0031] Schematic diagrams of exemplary signal generators according to various embodiments. [Figure 7]

[0032] Schematic diagrams of another exemplary signal generator according to various embodiments of a noise reduction circuit. [Figure 8]

[0033] Schematic diagrams of exemplary filter stages according to various embodiments. [Figure 9]

[0034] Schematic diagrams of exemplary sample stages according to various embodiments. [Figure 10]

[0035] Schematic diagrams of exemplary calibration circuits according to various embodiments. [Figure 11]

[0036] For example, flowcharts of various processes, procedures, and / or operations that can be performed by a controller of a quantum computer to determine a pre-distorted waveform. [Figure 12]

[0037] For example, flowcharts of various processes, procedures, and / or operations that can be performed by a controller of a quantum computer to provide a filtered pre-distorted signal to an electrode. [Modes for carrying out the invention]

[0024]

[0038] Next, the present invention will be described in more detail below with reference to the accompanying drawings illustrating some embodiments, rather than all embodiments, of the present invention. In practice, the present invention may be embodied in many different forms and should not be construed as being limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure satisfies applicable legal requirements. The term "or" (also indicated as " / ") is used herein in both the sense of a substitute and a conjunction unless otherwise specified. The terms "exemplary" and "exemplary" are used as examples that do not indicate a level of quality. The terms "generally" and "about" refer to the limits of engineering and / or manufacture and / or the user's ability to measure unless otherwise specified. Throughout, similar figures refer to similar elements.

[0025]

[0039] In various embodiments, methods, apparatus, systems, computer program products, etc., for generating and providing signals, as well as noise reduction circuits for quantum computing systems. For example, a signal may be generated (e.g., by a signal generator) and applied to the electrical components of a system (e.g., electrodes). The application of a signal to the electrical components may cause the system to perform a function. In various embodiments, the system may be configured to perform a variety of functions depending on the signal applied to the electrical components. In exemplary embodiments, different functions of the variety of functions may have different requirements with respect to the amount of acceptable noise in the applied signal and / or the frequency of the noise. In various embodiments, a gain stage may be used to amplify the signal, and / or a filter stage may be used to filter the signal (e.g., generated by a signal generator) before the signal is applied to the electrical components of a system. The filter stage may include an active filter, a passive filter, or a combination of an active filter and a passive filter. An active filter is a filter composed of active components (e.g., operational amplifiers, transistors, etc.) and which may have a response determined by these components. Furthermore, an active filter may be a dynamic filter which may have an operational response that can be dynamically changed (e.g., during the operation of the system). A passive filter is a filter that uses only passive components (e.g., resistors, capacitors, inductors, etc.) and has a response determined by these components.

[0026]

[0040] In exemplary embodiments, the system is a quantum computer. For example, the system may be a trap-type ion quantum computer that includes an ion trap containing multiple electrodes. Applying a signal (e.g., a voltage signal) to the electrodes of the quantum computer can cause the ion trap to perform various functions corresponding to the movement or maintenance of atomic objects (e.g., ions, atoms, etc.) trapped within the ion trap, and the atomic objects can be trapped at various locations within the ion trap. For example, one function may be to transport an atomic object from one location within the ion trap to another location within the ion trap. Atomic objects in the trap-type ion quantum computer move physically around the trap by using a signal (e.g., a waveform) generated by a signal generator (e.g., an arbitrary waveform generator (AWG)) and applied to the electrical components of the trap (e.g., electrodes). To move these ions rapidly, the AWG requires a very fast update rate. The control circuit for signal generation also controls other gate functions, including maintaining atomic objects in specific locations within an ion trap so that quantum logic gates can be executed on them, swapping the positions of two atomic objects within an ion trap, moving two atomic objects closer together, and moving two atomic objects that have been close together further apart.

[0027]

[0041] Each function may be associated with function-specific immunity (e.g., noise immunity, thermal immunity). For example, a specific response may be assigned to a function based on its function-specific noise immunity. Furthermore, during gating, in order to maintain high fidelity of the gating operation, the voltage at the electrodes must be very stable and have a very low noise spectral density (NSD).

[0028]

[0042] An example of a quantum computer including an ion trap. In exemplary embodiments, the system is or includes an atomic object confinement device (also referred to herein as a confinement device). In exemplary embodiments, the confinement device is an ion trap (e.g., a surface ion trap). For example, an ion trap may include a plurality of electrodes configured to receive electrical signals (e.g., voltages) to generate a potential field that controls the movement of one or more atomic objects (e.g., ions) within the ion trap.

[0029]

[0043] Various functions performed to control the movement of one or more atomic objects may have different requirements. One example of a requirement might be limiting noise in the electrical signals applied to electrodes, which may or may not be related to noise in the electric and / or magnetic fields generated by applying the electrical signals to the electrodes. For example, the noise requirement for performing a transport function, where an atomic object moves from one location within an ion trap to another within the ion trap, may be a first noise requirement, and the noise requirement for maintaining an atomic object in a particular location within the ion trap (e.g., so that a gate operation of a quantum computer, where the atomic object is a qubit, can be performed) may be a second noise requirement. In exemplary embodiments, the first and second noise requirements may differ. For example, when performing a transport function, the performance of the function may be susceptible to noise at a frequency of about 1 MHz. In another example, when performing a maintain function (e.g., maintaining an atomic object in a particular location within an ion trap so that a quantum logic gate can be performed on the atomic object), the performance of the function may be susceptible to noise at a frequency of about 250 kHz. Therefore, performing a transport function with noise requirements configured to optimize the performance of a maintain function will lead to a decrease in the performance of the transport function. For example, if a transport function is performed using noise requirements configured to optimize the performance of a maintenance function, the speed and / or bandwidth at which the transport function can be performed will be reduced. Another example of a requirement might be to limit the heat generated by and / or received by atomic objects in the electrical components of the confinement device and / or system, which may require optimizing or reducing the heat generated by noise reduction circuits or other circuits in the quantum computer and / or the heat generated through the operation of those circuits. In an exemplary embodiment, the heat generated by noise reduction circuits may be optimized or reduced by shaping or adjusting electrical signals, including using pre-distorted signals.

[0030]

[0044] Figure 1 provides a schematic diagram of an exemplary quantum computing system 100, including a confinement device (e.g., an ion trap 70), according to an exemplary embodiment. In various embodiments, the quantum computing system 100 includes a computing entity 10 and a quantum computer 110. In various embodiments, the computing entity 10 is configured to allow a user to provide input to the quantum computer 110 (e.g., through a user interface of the computing entity 10) and to receive, view, etc., outputs from the quantum computer 110. In various embodiments, the quantum computer 110 comprises a controller 30, a cryostat and / or vacuum chamber 40 enclosing a confinement device (e.g., an ion trap 70), and one or more operating sources 60. In exemplary embodiments, one or more operating sources 60 may include one or more lasers (e.g., optical lasers, microwave sources, etc.). In exemplary embodiments, beams, pulses, fields, etc., generated by the operating sources 60 may be provided to the ion trap 70 via one or more optical paths 66 (e.g., 66A, 66B, 66C). In various embodiments, one or more operating sources 60 are configured to manipulate and / or induce controlled quantum state evolution of one or more atomic objects within the confinement device. For example, in an exemplary embodiment in which one or more operating sources 60 include one or more lasers, the lasers may provide one or more laser beams to the confinement device in the cryostat and / or vacuum chamber 40. In various embodiments, the quantum computer 110 comprises one or more voltage sources 50. For example, the voltage sources 50 may include a plurality of voltage drivers and / or voltage sources, and / or at least one RF driver and / or voltage source. For example, the voltage sources 50 may include one or more signal generators, such as the signal generator 410 in Figure 4. The voltage sources 50 may be electrically coupled to the corresponding potential generating elements of the confinement device (e.g., ion trap 70) via one or more stages of an electrical circuit (e.g., a gain stage, a filter stage, and / or a sample stage) which may be in series or parallel with other stages.The gain stage and / or filter stage can shape the signal applied to the electrodes of the ion trap that captures atomic objects used as qubits in the quantum computer 110.

[0031]

[0045] Example Controller In various embodiments, a confinement device (e.g., an ion trap 70) is incorporated into the quantum computer 110. In various embodiments, the quantum computer 110 further comprises a controller 30 configured to control various elements of the quantum computer 110. In various embodiments, the controller 30 may be configured to control a voltage source 50, a cryogenic system and / or a vacuum system that controls the temperature and pressure within the cryostat and / or vacuum chamber 40, an operating source 60, and / or other systems that control various environmental conditions (e.g., temperature, humidity, pressure, etc.) within the cryostat and / or vacuum chamber 40, and / or may be configured to manipulate and / or induce a controlled evolution of the quantum states of one or more atomic objects within the confinement device. For example, the controller 30 may induce a controlled evolution of the quantum states of one or more atomic objects within the confinement device to execute quantum circuits and / or algorithms. In various embodiments, the atomic objects confined within the confinement device are used as qubits in the quantum computer 110.

[0032]

[0046] As shown in Figure 2, in various embodiments, the controller 30 may include various controller elements, including a processing element 205, a memory 210, a driver controller element 215, a communication interface 220, an analog-to-digital converter element 225, and so on. For example, the processing element 205 may include a programmable logic device (PLD), a composite PLD (CPLD), a microprocessor, a coprocessing entity, an application-specific instruction set processor (ASIP), an integrated circuit, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a programmable logic array (PLA), a hardware accelerator, other processing devices and / or circuits. The term "circuit" may refer to an entirely hardware embodiment or a combination of hardware and a computer program product. In an exemplary embodiment, the processing element 205 of the controller 30 may include a clock and / or be in communication with a clock.

[0033]

[0047] For example, memory 210 may include non-transient memory such as volatile and / or non-volatile memory storage, such as one or more of the following: hard disk, ROM, PROM, EPROM, EEPROM, flash memory, MMC, SD memory card, memory stick, CBRAM, PRAM, FeRAM, RRAM, SONOS, racetrack memory, RAM, DRAM, SRAM, FPM DRAM, EDO DRAM, SDRAM, DDR SDRAM, DDR2 SDRAM, DDR3 SDRAM, RDRAM, RIMM, DIMM, SIMM, VRAM, cache memory, register memory, etc. In various embodiments, memory 210 may store qubit records corresponding to the qubits of a quantum computer (e.g., in a qubit record data store, qubit record database, qubit record table, etc.), calibration tables, executable queues, computer program code (e.g., in one or more computer languages, specialized controller languages, etc.). In an exemplary embodiment, the execution of at least a portion of the computer program code stored in the memory 210 (for example, by the processing element 205) causes the controller 30 to perform one or more steps, operations, processes, procedures, etc., described herein for applying a signal to the electrodes of the ion trap 70 and performing a function corresponding to the signal.

[0034]

[0048] In various embodiments, the driver controller element 215 may include one or more drivers and / or controller elements configured to control one or more drivers. In various embodiments, the driver controller element 215 may include drivers and / or driver controllers. For example, a driver controller may be configured to operate one or more corresponding drivers according to executable instructions, commands, etc., scheduled and executed by the controller 30 (e.g., by the processing element 205). In various embodiments, the driver controller element 215 may enable the controller 30 to operate the operating source 60. In various embodiments, the drivers may be laser drivers, vacuum component drivers, drivers for controlling the flow of current and / or voltage applied to electrodes used to maintain and / or control the ion trap potential of the ion trap 70 (e.g., a voltage source 50), drivers for controlling the operating response of one or more dynamic filters (e.g., a filter driver which can be controlled by the controller to actuate the circuitry of the filter stage (e.g., switches or attenuators) to select a response), cryogenic and / or vacuum system component drivers, and the like. In various embodiments, the controller 30 may include one or more analog-to-digital converter elements 225 configured to receive signals from one or more optical receiver components, calibration sensors, etc. For example, in various embodiments, the controller 30 may include means for communicating and / or receiving signals from one or more optical receiver components such as cameras, MEM cameras, CCD cameras, photodiodes, photomultiplier tubes, etc.

[0035]

[0049] In various embodiments, the controller 30 may include a communication interface 220 for interfaceing with and / or communicating with the computing entity 10. For example, the controller 30 may include a communication interface 220 for receiving executable instructions, command sets, etc., from the computing entity 10 and for providing the output received from the quantum computer 110 (e.g., from an optical collection system) and / or the results of processing the output to the computing entity 10. In various embodiments, the computing entity 10 and the controller 30 may communicate via direct wired and / or wireless connections, and / or via one or more wired and / or wireless networks 20.

[0036]

[0050] Exemplary Computational Entity Figure 3 provides a schematic diagram of an exemplary computing entity 10 that may be used in conjunction with embodiments of the present invention. In various embodiments, the computing entity 10 is configured to allow a user to provide input to a quantum computer 110 (for example, through the user interface of the computing entity 10) and to receive, display, analyze, and so on, output from the quantum computer 110. The computing entity 10 may be in communication with the controller 30 of the quantum computer 110 via one or more wired or wireless networks 20 and / or via direct wired and / or wireless communication. In exemplary embodiments, the computing entity 10 may convert, configure, and format information / data, quantum computing algorithms, etc., into a computing language, executable instructions, command set, etc., that the controller 30 can understand and / or implement.

[0037]

[0051] As shown in Figure 3, the computing entity 10 may include an antenna 312, a transmitter 304 (e.g., a radio), a receiver 306 (e.g., a radio), and a processing element 308 that provides and receives signals from the transmitter 304 and the receiver 306, respectively. The signals provided to and received from the transmitter 304 and the receiver 306 may include signaling information / data in accordance with applicable radio system air interface standards for communicating with various entities such as a controller 30 and other computing entities 10. In this regard, the computing entity 10 may be able to operate with one or more air interface standards, communication protocols, modulation types, and access types. For example, the computing entity 10 may be configured to receive and / or provide communications using wired data transmission protocols such as fiber distributed data interface (FDDI), digital subscriber line (DSL), Ethernet, asynchronous transfer mode (ATM), Frame Relay, data over cable service interface specification (DOCSIS), or any other wired transmission protocol. Similarly, the computing entity 10 may be configured to receive and / or provide communications using general packet radio service (GPRS), Universal Mobile Telecommunications System (UMTS), Code Division Multiple Access 2000 (CDMA2000), CDMA2000 1X (1xRTT), Wideband Code Division Multiple Access (WCDMA), Global System for Mobile Communication (GSM), Enhanced Data Rate for GSM (EDGE).It may be configured to communicate over a wireless external communication network using any of the following protocols: Evolution, Time Division-Synchronous Code Division Multiple Access (TD-SCDMA), Long Term Evolution (LTE), Evolved Universal Terrestrial Radio Access Network (E-UTRAN), Evolution-Data Optimized (EVDO), High Speed ​​Packet Access (HSPA), High-Speed ​​Downlink Packet Access (HSDPA), IEEE 802.11 (Wi-Fi), Wi-Fi Direct, 802.16 (WiMAX), ultra-wideband (UWB), infrared (IR) protocol, near field communication (NFC) protocol, Wibree, Bluetooth protocol, wireless universal serial bus (USB) protocol, and / or any other wireless protocol. Computation entity 10 considers such protocols and standards to be Border Gateway Protocol (BGP), Dynamic Host Configuration Protocol (DHCP), Domain Name System (DNS), File Transfer Protocol (FTP), Hypertext Transfer Protocol (HTTP), HTTP over TLS / SSL / Secure, and Internet Message Access Protocol (IMAP).It can be used for communication using protocols such as Network Time Protocol (NTP), Simple Mail Transfer Protocol (SMTP), Telnet, Transport Layer Security (TLS), Secure Sockets Layer (SSL), Internet Protocol (IP), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), Datagram Congestion Control Protocol (DCCP), Stream Control Transmission Protocol (SCTP), and HyperText Markup Language (HTML).

[0038]

[0052] Computational entity 10 can communicate with various other entities via these communication standards and protocols, using concepts such as Unstructured Supplementary Service information / data (USSD), Short Message Service (SMS), Multimedia Messaging Service (MMS), Dual-Tone Multi-Frequency Signaling (DTMF), and / or Subscriber Identity Module Dialer (SIM dialer). Computational entity 10 can also download changes, add-ons, and updates to its firmware, software (including executable instructions, applications, and program modules), and operating system, for example.

[0039]

[0053] The computational entity 10 may also include a user interface device that includes one or more user input / output interfaces (e.g., a display 316 and / or speaker / speaker driver coupled to the processing element 308, and a touchscreen, keyboard, mouse, and / or microphone coupled to the processing element 308). For example, the user output interface may be configured to provide applications, browsers, user interfaces, interfaces, dashboards, screens, web pages, pages, and / or similar words used herein interchangeably, which run on and / or are accessible through the computational entity 10, for displaying or audibly presenting information / data and for interacting with information / data via one or more user input interfaces. The user input interface may include any of several devices that enable the computational entity 10 to receive data, such as a keypad 318 (hard or soft), a touch display, a voice / speech or motion interface, a scanner, a reader, or other input device. In embodiments including a keypad 318, the keypad 318 may include (or display) conventional numeric keys (0-9) and associated keys (#, *), as well as other keys used to operate the computational entity 10, and may include a set of keys that can be enabled to provide a complete set of alphabetic keys or a complete set of alphanumeric keys. In addition to providing input, certain functions, such as a screen saver and / or sleep mode, can be enabled or disabled using a user input interface, for example. The computational entity 10 can collect information / data, user interaction / input, etc., through such input.

[0040]

[0054] The computing entity 10 may also include volatile storage or memory 322 and / or non-volatile storage or memory 324, which may be embedded and / or removable. For example, non-volatile memory may be ROM, PROM, EPROM, EEPROM, flash memory, MMC, SD memory card, memory stick, CBRAM, PRAM, FeRAM, RRAM, SONOS, racetrack memory, etc. Volatile memory may be RAM, DRAM, SRAM, FPM DRAM, EDO DRAM, SDRAM, DDR SDRAM, DDR2 SDRAM, DDR3 SDRAM, RDRAM, RIMM, DIMM, SIMM, VRAM, cache memory, register memory, etc. The volatile and non-volatile storage or memory may store databases, database instances, database management system entities, data, applications, programs, program modules, scripts, source code, object code, bytecode, compiled code, interpreted code, machine code, executable instructions, etc., for performing the functions of the computing entity 10.

[0041]

[0055] Exemplary noise reduction circuit Figure 4 shows an exemplary noise reduction circuit 400 according to an exemplary embodiment. In various embodiments, the controller 30 can control one or more signal generators 410 to generate signals (e.g., voltage signals) and apply those signals to an electrical circuit (e.g., a noise reduction circuit 400) before applying them to electrical components (e.g., electrodes 440) of a system configured to perform multiple functions with different tolerances and / or requirements. In various embodiments, the noise reduction circuit 400 may be provided to each electrode 440 of a quantum computer 110, such as a noise reduction circuit 400 for each electrode 440 in a parallel arrangement (not shown). In other various embodiments, the noise reduction circuit 400 may provide signals to multiple electrodes 440 (not shown) of the quantum computer 110. The noise reduction circuit 400 may be configured to shape and / or adjust the signals applied to one or more electrodes 440 of the ion trap 70.

[0042]

[0056] As described above, the application of a signal to electrode 440 generates a potential field that can perform one or more functions on atomic objects trapped in ion trap 70. Different functions result in different sensitivities (such as noise sensitivity), and therefore different tolerances and requirements (e.g., noise requirements). Furthermore, sensitivity, tolerance, or requirements may be related to the function being performed. Therefore, the noise reduction circuit 400 can be used to shape and / or adjust the signal applied to electrode 440 by one or more signal generators 410, including noise reduction. In exemplary embodiments, signal generator 410 includes one or more waveform generators, which may be, for example, arbitrary waveform generators (AWGs) or digital-to-analog converters (DACs).

[0043]

[0057] In an exemplary embodiment, as shown in Figure 4, the noise reduction circuit 400 comprises a signal generator 410, a gain stage 420, and a filter stage 430. In some embodiments, the gain stage 420 and / or the filter stage 430 may be omitted. Alternatively, stages may be omitted, or one or more additional stages may be added. For example, in another exemplary embodiment, as shown in Figure 5, the noise reduction circuit 500 may include a sample stage 510. In the exemplary embodiment of Figure 5, the sample stage 510 is located after the filter stage, but in alternative embodiments, it may be located elsewhere in the noise reduction circuit, such as before the filter stage 430 or before the gain stage 420, or in parallel with one or more other stages. In various embodiments, the gain stage 420 applies gain to the signal generated by the signal generator 410.

[0044]

[0058] In various embodiments, the signal generator 410 may consist of one or more signal sources (e.g., a voltage source, a current source, an arbitrary waveform generator, a digital-to-analog converter, etc.). In an exemplary embodiment, as shown in Figure 6, the exemplary signal generator 600 may consist of an arbitrary waveform generator (AWG) 610, a digital-to-analog converter 620, and a switch 630, each of which may be controlled by a controller 30. In the exemplary embodiment of Figure 6, the controller 30 may provide signals to cause the AWG 610 to generate a signal and signals to cause the DAC 620 to generate a signal. The signal output by the signal generator 600 may be generated by the controller causing the switch 630 to select a signal from either the AWG 610 or the DAC 620. Thus, the signals from the AWG 610 and the DAC 620 may be selected to combine the signal from the AWG 610 and the signal from the DAC 620. The selection of a signal from either the AWG610 or the DAC620, or the switching to generate a signal consisting of their respective outputs, may depend, for example, on the current capabilities or phase of the quantum computer 110.

[0045]

[0059] In alternative embodiments not shown, for example, there are alternative methods for combining the outputs of AWG610 and DAC620. For example, switch 630 may be omitted, and controller 30 can generate a signal from either AWG610 or DAC620, or both, to generate a signal that will be the output of the signal generator. In alternative examples, servos may be used to reference AWG610 and DAC620 (e.g., conventional integrators or Deboo integrators), bias T may be used, or voltage adders may be used. Alternatively, or additionally, switch 630 may be replaced by, for example, an adder, divider, or averager that can be used to generate the output signal. Furthermore, the signal generator 600 may include three or more signal sources (not shown), and multiple switches may be used together with adders, dividers, or averagers. Furthermore, the controller can control the signals from AWG610 and DAC620 so that the signals generated as the output of signal generator 600 are pre-distorted and / or shaped, and the pre-distortion and / or shaping may be based on measurements obtained with respect to the noise reduction circuit or downstream circuit. The coupling of signals from the signal sources (e.g., AWG610 and DAC620) may not be equal in duration or for equal duration. For example, switch 630 may pass the signal from AWG610 for a greater duration (e.g., 75%) than the duration (e.g., 25%) of the signal from DAC620. Furthermore, the controller 30 may prevent either AWG610 or DAC620 from generating a signal.

[0046]

[0060] The controller 30 can cause the signal generator 410 to generate a specific signal by controlling how each signal source of the signal generator 410 generates a signal. Thus, the signal generated by the signal generator 410 may be generated for a specific electrical circuit and / or electrode to which the signal is provided.

[0047]

[0061] Figure 7 shows a further embodiment of the signal generator 410, reference no. 710. The signal generator 710 comprises an AWG 720 and a DAC 730, as well as a gain stage 740. Although not shown in Figure 7, the gain stage may be located after the AWG 720, or both the AWG 720 and the DAC 730 may have their own gain stages within the signal generator 710. Circuits 750 and 760 are also shown in Figure 7, which may be the same circuit or separate circuits. For example, circuits 750 and 760 may be electrical junctions, or alternatively, each may be a switch (for example, shown as circuit 760 in Figure 7) or other circuit for coupling two inputs to one output. As shown in Figure 7, the input to circuit 760 may be the output of a stage after a noise reduction circuit, such as the output of the gain stage 420 or the input to electrode 440, which are the same signals as in Figure 7, but may be different signals in Figure 4 or 5, for example.

[0048]

[0062] In various embodiments, the filter stage 430 may include a plurality of filters (e.g., two or more) (e.g., not shown in Figure 7), and the filters may be of the same type or different types (e.g., low-pass filters, high-pass filters, band-pass filters, and / or band-stop filters). Furthermore, each filter may be a single-terminated type filter with a specific filter response (e.g., Butterworth, Bessel, Chebyshev, elliptic, Reglende, etc.). In various embodiments, various filters (e.g., having various responses) may be used. The filters may be active filters or passive filters.

[0049]

[0063] In an exemplary embodiment as shown in Figure 8, the exemplary filter stage 800 may consist of an active filter 810 and a passive filter 820. Although Figure 8 shows a single active filter 810 and a single passive filter 820, exemplary embodiments may have one or more active filters and one or more passive filters in the filter stage. Furthermore, although not shown, the active and passive filters may be arranged in various orders (for example, a passive filter before an active filter).

[0050]

[0064] The filtering of the signal output by the filter stage 800 may be determined, for example, by the output of the active filter 810 and the output of the passive filter 820. The filtering of the filter stage 800 is to ensure that the signal output from the filter stage 800 satisfies the requirements and tolerance of the electrodes 440, and this filtering may be, for example, a target filter function. The target filter function may consist of its constituent electrodes, some of which are assigned to each filter (e.g., the active filter 810, the passive filter 820). In an exemplary embodiment, the real electrodes and the pair of electrodes with the least attenuation are assigned to the passive filter 820, and the remaining electrodes are assigned to the active filter 810. In this embodiment, this assignment of electrodes can prevent the under-attenuated response from clipping the operational amplifier and reduce nonlinear behavior. From the electrode assignment, the active filter 810 and the passive filter 820 may be determined. In an alternative embodiment, the electrodes assigned to the passive filter may be low-frequency electrodes. Furthermore, in exemplary embodiments, the pre-distorted signal from the signal generator 410 may be generated based on measurements from the filter stage 800, and may include a pre-distorted signal that includes a portion of the signal to be removed by the filter. The pre-distorted signal may be generated so as to be partially removed due to the capabilities of the signal source of the signal generator 410.

[0051]

[0065] In an exemplary embodiment, the active filter 810 may provide noise shaping, and the passive filter 820 may remove residual noise that may arise from the operational amplifier of the active filter 810. The design of the component including the active filter may include, for example, registers to minimize noise. Furthermore, buffers (not shown) may be used at the input and / or output of the active filter 810. A buffer at the input may, for example, address the low impedance of the active filter 810. A buffer at the output may, for example, be used to drive the passive section.

[0052]

[0066] In an exemplary embodiment, the passive filter 820 may be designed so that an infinite output impedance drives the electrodes, and the input impedance may be selected so that the inductor value matches a desired value.

[0053]

[0067] Therefore, the controller 30 can control the signal generator 410 to provide a specific signal. The controller 30 can also control the filter stage 430 to control the operating response of the filter. The filter stage 430 receives the signal generated by the signal generator 410 and can filter the signal according to the operating response selected by the controller 30. The filtered signal is then provided to the electrode 440, which can then perform a function using the resulting potential field. Furthermore, the filtered signal provided to the electrode 440 has a suitable profile within the necessary tolerance (e.g., noise immunity) for the function performed via the potential field resulting from the application of the signal to the electrode 440.

[0054]

[0068] In exemplary embodiments such as those shown in Figure 5, a sampling stage 510 can be used along with the signal before it is provided to the electrodes. The signal input to the sampling stage may have more noise than desired, and noise on the electrodes may reduce the fidelity of gates performed near the electrodes. For example, in embodiments where the gain stage 420 and / or filter stage 430 are omitted, the output of the signal generator may have more noise than the output of the precision operational amplifier. For example, the output of the DAC may have noise on the order of tens to hundreds of nanovolts, while the precision operational amplifier may have noise on the order of a few nanovolts. In some embodiments, the use of the sampling stage 510 may reduce the detrimental effect of the instrument noise spectral density (NSD) on the electrodes 440 and may eliminate the need for larger or additional filters. In some embodiments, the output of the sampling stage 510 may be to an analog-to-digital converter that can assist sampling by acting as a buffer, for example. In some embodiments, the sampling stage may be a buffer to reduce noise or circuit complexity. In some embodiments, the noise to be reduced may be noise generated by the signal generator.

[0055]

[0069] Figure 9 shows a schematic diagram of an exemplary sample stage 510. In an exemplary embodiment, the sample stage 510 comprises a switch 910, a capacitor 920 (which may be grounded), and an operational amplifier 930. The switch 910 may be opened or closed, for example, based on a mode or operation or function (e.g., transport or gating). The switch 910 may be, for example, a JFET (not shown). When the JFET is switched on, the capacitor 920 may be charged. Once the capacitor is charged, the JFET closes the circuit, and the operational amplifier 930 acts as a buffer for the capacitor 920, holding the capacitor's voltage at the output of the sample stage 510. The capacitor may be charged by a voltage source, for example, a DAC that can generate a signal based on an input from the controller 30.

[0056]

[0070] Feedback circuit The bandwidth of the signal applied to the electrodes may be limited by the noise reduction circuit. In an exemplary embodiment, to overcome the bandwidth limitation, the signal generated by the signal generator 410 may be shaped using, for example, pre-distortion. This may overcome, for example, the delay and / or attenuation of the filter. Furthermore, the signal may generate unwanted heat that reduces the processing of the quantum circuit, and this heat can be reduced by using a pre-distorted signal. In an exemplary embodiment, the feedback circuit enables the determination of a pre-distorted signal, such as a signal that can reduce the heat generated.

[0057]

[0071] Figure 10 shows a schematic diagram of an exemplary noise reduction circuit including a feedback circuit 1000. In the embodiment shown in Figure 10, the exemplary noise reduction circuit including the feedback circuit 1000 may consist of additional switches (e.g., switches 1010 and 1020) and a converter 1030. In the exemplary embodiment, the converter 1030 is an analog-to-digital converter. Switches 1010 and 1020 may be, for example, one-to-N switches (e.g., one input to two outputs) or N-to-1 switches (e.g., two inputs to one output). Furthermore, switch 1010 or switch 1020 may be a combination of one or more switches, such as an N-to-1 switch and a one-to-N switch, which allows one of several inputs to be selected and output with one of N outputs. The use of switches makes it possible to isolate one or more parts of the noise reduction circuit, and one or more parts may be used for calibration, characterization, or diagnosis of the noise reduction circuit. This can be done by inputting the switch output to the converter 1030, as shown in Figure 10. The signal input to the converter 1030 may be converted from an analog signal to a digital signal, for example, to determine characteristics of a noise reduction circuit that enable calibration of the signal output by the signal generator 410 or diagnosis of the noise reduction circuit.

[0058]

[0072] Figure 10 shows two switches (switch 1010 and switch 1020), but additional switches may be present to isolate additional circuits. For example, referring to Figure 10, a switch can be placed between the gain stage 420 and the filter stage 430 to allow isolation of the filter stage 430. As a further example, if a sample stage (not shown in Figure 10) is present, the sample stage can be isolated using switches before, after, or before / after the sample stage. The sample stage may be located, for example, after the filter stage 430 but before switch 1020 in Figure 10.

[0059]

[0073] In an exemplary embodiment, the signal generator 410 may include two or more signal sources. The controller 30 can generate separate signals from each of the signal sources of the signal generator 410, and can use switches 1010 and 1020 to isolate parts of the noise reduction circuit and direct the signals to pass through or around specific stages and / or components of the noise reduction circuit in order to determine the characteristics of each signal generated separately or in different combinations (for example, a duty cycle where 75% of the first signal comes from the first signal source and 25% of the second signal comes from the second signal source).

[0060]

[0074] In the exemplary calibration routine shown in Figure 11, in order to overcome the bandwidth limitations of the circuit, minimize noise, and minimize heat, the signal output by the signal generator 410 can be calibrated by measuring the response of a noise reduction circuit, including a feedback circuit 1000, to determine the pre-distorted waveform that the signal generator 410 should generate.

[0061]

[0075] Figure 11 provides a flowchart illustrating exemplary processes, procedures, and operations that may be performed by the controller 30 to determine, for example, a pre-distorted waveform that can be generated by the signal generator 410. For clarity, the focus is on applying a signal with dynamically shaped noise to a single electrode 440. However, as can be understood, the system may include multiple signal generators 410, multiple gain stages, filter stages, and / or sampling stages, so that signals with pre-distorted waveforms and / or different pre-distorted waveforms can be supplied to multiple electrodes 440 and / or other electrical components.

[0062]

[0076] Starting from step / operation 1110, using an exemplary noise reduction circuit including the feedback circuit 1000 in Figure 10, the signal generator 410 can be isolated by the operation switch 1010 so that the output of the signal generator 410 is input to the converter 1030.

[0063]

[0077] In step / operation 1120, the signal generator 410 can generate a first frequency sweep over a range of frequencies. The frequency range may be determined, for example, by the characteristics of the signal generator 410, or alternatively, by the characteristics of another part of the noise reduction circuit, such as a filter stage. For example, if the characteristics of the filter stage allow only signals with frequencies below 10 kHz to pass through, the upper limit of the first frequency sweep may be 10 kHz. Alternatively, there may be no limit to the frequency of the frequency sweep other than the frequencies that the signal generator 410 can generate.

[0064]

[0078] In step / operation 1130, the transducer 1030 measures a first response to a first frequency sweep generated by the signal generator 410. This first measurement by the transducer 1030 may be provided to the controller 30.

[0065]

[0079] In step / operation 1140, switches 1010 and 1020 may be operated to isolate noise reduction electrical circuits. For example, switch 1010 may be operated to receive the output of signal generator 410 as input and output that signal to gain stage 420, and switch 1020 may be operated to receive the output of filter stage 430 as input and output that signal to converter 1030. In this step in this example, the output of signal generator 410 is sent only to gain stage 420, and the output of filter stage 430 is sent only to converter 1030. In an alternative example, if there are two or more gain stages, or two or more filter stages, or sampling stages, the switches may be operated to isolate each stage so that the output of each stage is provided to converter 1030.

[0066]

[0080] Continuing this example, in step / operation 1150, the signal generator 410 generates a second frequency sweep which may be the same signal as the first frequency sweep. The second frequency sweep may or may not be limited based on the characteristics of the electrical circuit described above.

[0067]

[0081] In step / operation 1160, the transducer 1030 measures a second response to a second frequency sweep generated by the signal generator 410 and transmitted through switch 1010, gain stage 420, filter stage 430, and switch 1020, as shown in Figure 10. This second measurement by the transducer 1030 may be provided to a controller 30 that can use the measurement. In some embodiments, the controller may analyze the second measurement (e.g., frequency domain analysis), and the second measurement may be used in further operations, such as determining a pre-distorted waveform. Furthermore, the signal provided to the transducer 1030 may be small, and an additional gain stage (not shown) may be placed before the transducer 1030.

[0068]

[0082] In step / operation 1170, the first and second measurements can be used to determine a pre-distorted waveform that may be used in the electrical circuit in this example. For example, by dividing the second measurement by the first measurement, the frequency response of the gain stage 420 and filter stage 430, which are the electrical circuits through which the signal passes before being input to electrode 440 in the example shown in Figure 10, can be determined. The determined frequency response is an improvement over the analytical or theoretical model of the electrical circuit due to differences in the physical components used in the electrical circuit. Therefore, the determined frequency response can be used to determine a pre-distorted waveform that can be used in the noise reduction circuit of Figure 10 to generate a pre-distorted waveform that reduces noise and heat that may be generated from the signal generated from the signal generator 410 passing through the noise reduction circuit, and / or that may be generated by filtering, amplifying, and / or other adjustments of the signal generated from the signal generator 410.

[0069]

[0083] Figure 12 is a flowchart of various processes, procedures, and / or operations that may be performed, for example, to provide a filtered pre-distorted signal to electrodes. In an exemplary embodiment, after determining the pre-distorted waveform to be applied, in step 1210, the signal generator 410 generates a pre-distorted signal having the pre-distorted waveform. As step 1220, the pre-distorted signal is provided to the gain stage 420, which applies gain to the pre-distorted signal. In step 1230, the pre-distorted signal with gain is provided to the filter stage 430 for filtering the signal. In step 1240, the filtered pre-distorted signal is provided to one or more electrodes 440. Although Figure 12 deals with a pre-distorted signal generated by the signal generator 410, in an exemplary embodiment, the same steps may be used to provide a signal to one or more electrodes where the signal is not pre-distorted.

[0070]

[0084] An alternative to the frequency sweep described above for use in Figure 11 is to use a DC voltage instead of a frequency sweep. Using a DC voltage may allow the noise spectral density of the noise reduction circuit to be measured using the measurement obtained by the ADC. Another alternative is to use a pulse instead of a frequency sweep. Another alternative is that the signal may be a frequency sweep, a pulse, and / or a DC voltage.

[0071]

[0085] In various alternative embodiments, the order in which the signal (e.g., frequency sweep) is applied to the parts of the noise reduction circuit can vary.

[0086] Furthermore, feedback circuits can be used to verify the health of the noise reduction circuit. The health of a stage can be determined by isolating the stage or a portion of a stage and measuring the response of the entire isolated stage. For example, if a component fails, it may be possible to isolate the stage from the noise reduction circuit, measure the response of that stage, and compare the measured response to an expected response (e.g., a theoretical response) or a previously measured response. By verifying the health of the noise reduction circuit in this way, a diagnosis may be possible. In some exemplary embodiments, such a diagnosis may be automated and performed periodically.

[0072]

[0087] In further embodiments, a feedback circuit is used to perform time-domain reflectometry (TDR). TDR can enable the measurement of an impedance-indicating response related to a portion of the circuit that may otherwise be inaccessible. Furthermore, TDR can enable the measurement of a response from a downstream circuit of the noise reduction circuit (e.g., electrode 440), thereby providing feedback on the health of the noise reduction circuit or the downstream circuit. Switches (e.g., switches 1010 and 1020 in Figure 10) can be used to isolate part or all of the noise reduction circuit 400 to perform TDR. Isolation of the noise reduction circuit may be beneficial, among other reasons, to isolate an amplifier (e.g., gain stage 420). For example, a signal generator 410 may generate pulses. These pulses may be transmitted through various stages (or parts of stages) of the noise reduction circuit 400, such as the gain stage 420 and / or the filter stage 430, or they may bypass the noise reduction circuit 400. When a pulse passes through a component including a connector junction (e.g., a component in a stage or downstream circuit), signal reflections can be generated. Reflections can provide telemetry data when they are generated, which may be due to, for example, an open or faulty component or circuit. The amplitude and dispersion characteristics of the measured reflections provide insights into the quality of the stage, downstream circuitry, components in the stage or downstream circuitry, and connections. Examples of these insights include impedance measurements and the location where the reflection was generated (e.g., in a faulty component or circuit, an open circuit, or a component that is causing the open circuit).

[0073]

[0088] In further embodiments, a feedback circuit is used to measure the noise spectral density (NSD). For example, the signal generator 410 can be connected to the transducer 1030 via switch 1010, and the output of the signal generator 410 can be set to a DC voltage signal to measure the NSD of the signal generator 410. In further embodiments, the NSD of the electrode 440 can be measured by connecting the electrode 440 to the transducer 1030 (without connecting the signal generator 410 or the gain stage 420 or the filter stage 430). The ion trap 70 may have two or more electrodes 440, and the circuits that provide signals to these additional electrodes may be in physical proximity to the noise reduction circuits and / or the electrodes 440. The NSD measurement of the electrode 440 can measure, for example, whether there are unwanted signals emitted to the electrode 440, or crosstalk between circuits that provide signals to other electrodes.

[0074]

[0089] In an alternative embodiment, the feedback circuit may be able to generate a response using a frequency sweep. For example, a signal generator 410 can be connected to the electrode 440 and the transducer 1030 via switches 1010 and 1020, and the output of the signal generator 410 can be set to a frequency sweep to measure the response of the electrode (or other downstream circuit). The response can measure, for example, the expected change in response at a particular frequency. Such a change could be, for example, a thermal variation in a component or circuit.

[0075]

[0090] Insights gained from verifying system health can minimize downtime and improve system troubleshooting. Alternatively, or in addition, health checks may be performed at runtime, for example, while the system is shut down for maintenance, or, as another example, while a part of the system is isolated, so that insights can be learned to address system health. Health checks may enable real-time waveform pre-distortion to address the response received from the check. Furthermore, from the response, a pre-distorted waveform may be determined and generated to take into account the tolerances measured within the system (e.g., manufacturing tolerances) and to compensate for variations that occur during use (e.g., thermal variations).

[0076]

[0091] In alternative embodiments, noise in noise reduction circuits, electrodes, or other downstream circuits may fluctuate due to nearby test equipment or other electrical or mechanical systems (e.g., in the same room or alternative part of the system). Health checks may reveal that the use of other systems introduces noise in the system, for example, components, stages (e.g., gain stage 420), or electrodes 440. For example, feedback from health checks using TDR, NSD, or frequency sweep can be used to pre-distort the signal to compensate for noise occurring in the system. Additionally, or alternatively, noise may be addressed by the controller 30 adjusting the signal generator 410 to generate a signal to, for example, turn off the system, or by the noise reduction circuit or feedback circuit to isolate the noisy portion of the system. For example, if high fidelity is required in the operation of the electrodes, the system can be checked before the signal is generated to determine that the noise is within acceptable limits (or absent).

[0077]

[0092] Technical advantages Various embodiments provide technical solutions to the technical problem of generating and providing signals to a system that cause the system to perform different functions with different tolerances or requirements. For example, in the exemplary system of the trap-type ion quantum computer described above, when performing the transport function, the performance of the function may be susceptible to noise at frequencies such as about 1 MHz, and / or when performing the maintenance function (e.g., maintaining atomic objects in specific locations within an ion trap so that quantum logic gates can be executed on atomic objects), the performance of the function may be susceptible to noise at frequencies such as about 250 kHz. Conventional methods of noise shaping signals involve filtering all signals based on the noise tolerance of the function with the most stringent noise tolerance. However, performing the transport function with noise requirements configured to optimize the performance of the maintenance function may lead to a decrease in the performance of the transport function. For example, performing the transport function with noise requirements configured to optimize the performance of the maintenance function reduces the speed and / or bandwidth at which the transport function can be performed. The exemplary embodiments provided herein describe technical solutions to these technical problems by providing noise reduction circuits for providing signals to electrodes that satisfy the noise requirements and noise tolerances required for multiple functions. Thus, the exemplary embodiments provide technical solutions that lead to improved system performance.

[0078]

[0093] For example, to meet the low-noise requirements of electrode 440, the signal generator 410 may consist of two or more voltage sources, and the signal generator 410 may generate a signal by combining the outputs of each voltage source. This combination of signals from two or more voltage sources can reduce the noise generated by a system using only one voltage source.

[0079]

[0094] In another example, to meet the low-noise requirements of electrode 440, the filter stage 430 may consist of at least one active filter and at least one passive filter. This filter stage 430 can provide an improvement over the case of a passive filter alone, which may require an inductor that is physically too large or has too many parasitic losses and / or too high tolerance for a comparable passive filter in the quantum computer 110. This filter stage 430 can also provide an improvement over the case of an active filter alone, which may require an operational amplifier that generates too much residual noise for the required tolerance.

[0080]

[0095] In another example, the use of a feedback circuit in a noise reduction circuit can make it possible to determine the pre-distorted waveform of a signal. The pre-distorted waveform can be determined from measurements taken from a portion of the noise reduction circuit, thereby making it possible to determine a pre-distorted waveform that minimizes the noise and / or heat generated from supplying a signal to these portions of the noise reduction circuit.

[0081]

[0096] conclusion Those skilled in the art, who benefit from the teachings presented in the foregoing description and the accompanying drawings, will likely conceive of many modifications and other embodiments of the invention described herein. Therefore, it should be understood that the invention is not limited to the specific embodiments disclosed, and that modifications and other embodiments are intended to be included within the scope of the appended claims. Certain terms are used herein, but these are used in a general and descriptive sense only and not for limiting purposes. [Explanation of Symbols]

[0082] 10 Computation Entities 30 controllers 40 Vacuum Chamber 50 Voltage source 60 Operation source 66 Light path 70 Ion trap 100 Quantum Computer Systems 110 Quantum Computers 205 Processing Elements 210 memory 215 Driver Controller Elements 220 Communication Interfaces 225 Analog-to-Digital Converter Element 312 Antenna 304 Transmitter 306 Receiver 308 processing elements 316 displays 318 Keypad 322 Volatile storage or memory 324 Non-volatile storage or memory 400 Noise Reduction Circuit 410 Signal Generator 420 Gain Stage 430 filter stages 440 electrode 500 Noise Reduction Circuit 510 sample stages 600 signal generator 630 switches 710 signal generator 720 AWG 730 DAC 800 filter stages 810 Active Filter 820 Passive Filters 910 Switch 920 Capacitor 930 Operational Amplifier 1000 Feedback Circuit 1010 Switch 1020 Switch 1030 Converter

Claims

1. A system for providing signals to electrodes in an ion trap of a quantum computer, A signal generator configured to generate a first signal, wherein the first signal includes a frequency sweep, A gain stage configured to amplify the aforementioned signal, wherein the input to the gain stage is connected to the output of the signal generator, A filter stage configured to filter the aforementioned signal, wherein the input to the filter stage is connected to the output of the gain stage, The system includes a converter configured to measure a response at the output of the filter stage in response to the first signal, The signal generator is further configured to generate a second signal, the second signal being pre-distorted based on the measured response, A system in which electrodes in an ion trap are configured to receive the second signal.

2. The system according to claim 1, wherein the filter stage includes an active filter and a passive filter, the signal generator includes a first digital-to-analog converter and a second digital-to-analog converter, the second digital-to-analog converter is configured to provide a DC offset voltage, and the first digital-to-analog converter is configured to provide the pre-distorted second signal.

3. The system according to claim 1, wherein the output of the signal generator connected to the input of the gain stage is connected via a switch, and the switch switches between connection to the input of the gain stage and connection to the converter.

Images