Parameter optimization method and device for readout signal of multi-qubit and quantum computer

Abstract

The application provides a parameter optimization method and device for a read signal of a multi-qubit and a quantum computer, wherein when the parameters of the read signal of the multi-qubit are optimized, first, the parameters of the read signal corresponding to each to-be-read qubit are set based on the to-be-read qubits respectively, then the read signal is applied to the corresponding read data bus to obtain a corresponding read feedback signal, and measurement data of each to-be-read qubit is obtained based on the read feedback signal; wherein the measurement data is scatter data in an IQ coordinate system, finally, the parameters of the read signal corresponding to each to-be-read qubit are optimized based on the distribution characteristics of the measurement data of each to-be-read qubit in the IQ coordinate system, so that the parameters of the read signal of the associated multi-qubit are optimized, the accuracy of the measurement result is ensured, the multi-associated qubits can be applied, the practicability of the multi-associated qubits is improved, and the application scenarios of the multi-associated qubits are expanded.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of quantum measurement and control, and particularly relates to a parameter optimization method and device for read signals of multiple quantum bits and a quantum computer. BACKGROUND

[0002] Quantum bit information refers to the quantum state of a quantum bit. The basic quantum states are |0> state and |1> state. After the quantum bit is operated, the quantum state of the quantum bit changes. On a quantum chip, the change of the quantum state possessed by the quantum bit after the quantum chip is executed is the execution result of the quantum chip, which is carried by a quantum bit read signal (generally an analog signal) and transmitted out.

[0003] The process of quickly measuring the quantum state of a quantum bit through a quantum bit read signal is a key work to understand the execution performance of a quantum chip. High accuracy of quantum bit measurement results has been an important indicator that the quantum computing industry has been continuously pursuing. The existing technology is relatively mature in determining the measurement result of a single quantum bit that is not affected by other quantum bits. However, multiple associated quantum bits have more practical and broad application prospects. For example, two associated quantum bits running a double quantum logic gate or multiple associated quantum bits running a multi-quantum logic gate; for another example, multiple associated quantum bits running a quantum computing task. In these examples, the determination of the measurement result of multiple associated quantum bits is particularly important. However, so far, the accuracy of the measurement result of multiple associated quantum bits is difficult to guarantee, mainly due to the influence of the read signals of multiple associated quantum bits. Therefore, how to optimize the parameters of the read signals of associated multiple quantum bits to ensure the accuracy of the measurement result is a problem that needs to be solved at present. SUMMARY

[0004] The present application aims to provide a parameter optimization method and device for read signals of multiple quantum bits and a quantum computer to solve the defects and deficiencies in the prior art. The present application can optimize the parameters of the read signals of associated multiple quantum bits to ensure the accuracy of the measurement result, so that multiple quantum bits can be applied.

[0005] To achieve the above-mentioned purpose, in a first aspect, the present application provides a parameter optimization method for read signals of multiple quantum bits. A quantum chip is provided with multiple quantum bits arranged in sequence and multiple read data buses. Each read data bus is coupled to multiple quantum bits. The parameter optimization method comprises the following steps:

[0006] respectively based on the to-be-read quantum bits, parameters of corresponding read signals are set; wherein the read signals of the to-be-read quantum bits located on the same read data bus are the same, the read signals are obtained by mixing a middle frequency signal, and the middle frequency signal contains modulation and coding information required by the quantum bits for quantum computation;

[0007] The read signals are respectively applied to the corresponding read data buses to obtain corresponding read feedback signals;

[0008] Measurement data of the to-be-read quantum bits are obtained based on the read feedback signals; wherein the measurement data are scatter data in an IQ coordinate system;

[0009] Parameters of the corresponding read signals are respectively optimized based on distribution characteristics of the measurement data of the to-be-read quantum bits in the IQ coordinate system.

[0010] Optionally, the setting of the parameters of the corresponding read signals based on the to-be-read quantum bits respectively comprises:

[0011] Frequencies of the read signals are respectively determined, and powers of the read signals are preset;

[0012] Frequencies and amplitudes of the middle frequency signals corresponding to the to-be-read quantum bits are respectively determined.

[0013] Optionally, the determination of the frequencies of the read signals comprises:

[0014] Read frequencies of all the quantum bits coupled and connected on the read data bus corresponding to each to-be-read quantum bit are respectively obtained;

[0015] The frequencies of the read signals corresponding to the read data bus are respectively determined based on the read frequencies of all the quantum bits on the read data bus.

[0016] Optionally, the determination of the read frequencies of the read signals corresponding to the read data bus based on the read frequencies of all the quantum bits on the read data bus comprises:

[0017] The median of the read frequencies of all the quantum bits on the read data bus is respectively determined based on the read frequencies of all the quantum bits on the read data bus;

[0018] The median of the read frequencies of the quantum bits is set as the frequency of the read signal of the corresponding read data bus.

[0019] Optionally, the determination of the frequencies and amplitudes of the middle frequency signals corresponding to the to-be-read quantum bits comprises:

[0020] determining the frequency of the intermediate frequency signal corresponding to the to-be-read quantum bit based on a first preset relationship; wherein the frequency of the intermediate frequency signal corresponding to the to-be-read quantum bit, the frequency of the read signal, the read frequency corresponding to the to-be-read quantum bit and the preset frequency of the intermediate frequency signal satisfy the first preset relationship;

[0021] determining the amplitude of the intermediate frequency signal corresponding to the to-be-read quantum bit based on a second preset relationship; wherein the amplitude of the intermediate frequency signal corresponding to the to-be-read quantum bit, the preset amplitude of the intermediate frequency signal, the power of the read signal and the read power corresponding to the to-be-read quantum bit satisfy the second preset relationship.

[0022] Optionally, the first preset relationship is:

[0023] If’=Fc-Fc’+If, wherein If’ is the frequency of the intermediate frequency signal corresponding to the to-be-read quantum bit, Fc is the frequency of the read signal, Fc’ is the read frequency corresponding to the to-be-read quantum bit, and If is the preset frequency of the intermediate frequency signal.

[0024] Optionally, the second preset relationship is:

[0025] Amp’=Amp×10^[(Pc’-10dB-Pc) / 2], wherein Amp’ is the amplitude of the intermediate frequency signal corresponding to the to-be-read quantum bit, Amp is the read waveform amplitude corresponding to the to-be-read quantum bit, Pc’ is the power of the read signal, and Pc is the read power corresponding to the to-be-read quantum bit.

[0026] Optionally, the parameters of the read signal corresponding to each to-be-read quantum bit are optimized based on the distribution characteristics of the measurement data of each to-be-read quantum bit in the IQ coordinate system, specifically including:

[0027] establishing a criterion in the IQ coordinate system; wherein the criterion is used to reflect the distribution characteristics of the measurement data of each to-be-read quantum bit in the IQ coordinate system;

[0028] determining whether the measurement data of each to-be-read quantum bit satisfies a preset condition based on the criterion, and if not, optimizing the parameters of the read signal corresponding to the to-be-read quantum bit.

[0029] Optionally, the preset condition includes a first preset condition, and the determining whether the measurement data of each to-be-read quantum bit satisfies a preset condition based on the criterion, and if not, optimizing the parameters of the read signal corresponding to the to-be-read quantum bit, specifically includes:

[0030] determining whether the measurement data of each to-be-read quantum bit satisfies a first preset condition based on the criterion;

[0031] If no, the amplitude of the intermediate frequency signal corresponding to the to-be-read quantum bit is reduced by a preset step within a preset range, and the read signal is updated.

[0032] Optionally, the preset condition further includes a second preset condition, and after the measurement data of each to-be-read quantum bit is judged based on the criterion whether the first preset condition is met, the method further includes:

[0033] If yes, the measurement data of each to-be-read quantum bit is judged based on the criterion whether the second preset condition is met.

[0034] If no, the frequency of the intermediate frequency signal corresponding to the to-be-read quantum bit is reduced or increased by a preset step within a preset range, and the read signal is updated.

[0035] Optionally, the preset condition further includes a third preset condition, and after the measurement data of each to-be-read quantum bit is judged based on the criterion whether the second preset condition is met, the method further includes:

[0036] If yes, the measurement data of each to-be-read quantum bit is judged based on the criterion whether the third preset condition is met.

[0037] If no, the frequency and / or amplitude of the intermediate frequency signal corresponding to the to-be-read quantum bit is reduced or increased by a preset step within a preset range, and the read signal is updated.

[0038] In a second aspect, the present application provides a parameter optimization device for a read signal of a multi-qubit, comprising:

[0039] A setting module is configured to set the parameters of the read signal corresponding to each to-be-read quantum bit based on the to-be-read quantum bit respectively.

[0040] An applying module is configured to apply the read signal to the read data bus to obtain a read feedback signal.

[0041] An obtaining module is configured to obtain the measurement data of each to-be-read quantum bit based on the read feedback signal.

[0042] An optimization module is configured to optimize the parameters of the read signal corresponding to each to-be-read quantum bit based on the distribution characteristics of the measurement data of the to-be-read quantum bit in the IQ coordinate system.

[0043] In a third aspect, the present application provides a quantum computer, which applies the parameter optimization method for a read signal of a multi-qubit as described in the first aspect to optimize the parameters of the read signal of the multi-qubit, or comprises the parameter optimization device for a read signal of a multi-qubit as described in the second aspect.

[0044] Compared with the prior art, the multi-qubit reading signal parameter optimization method, device and quantum computer provided by the application have the following beneficial effects: when the parameters of the reading signals of the multi-qubits are optimized, first, the parameters of the reading signals corresponding to each to-be-read qubit are set based on each to-be-read qubit respectively, then the reading signals are applied to the corresponding reading data bus to obtain corresponding reading feedback signals, and the measurement data of each to-be-read qubit is obtained based on the reading feedback signals; wherein the measurement data is scatter data in an IQ coordinate system, finally, the parameters of the reading signals corresponding to each to-be-read qubit are optimized based on the distribution characteristics of the measurement data of each to-be-read qubit in the IQ coordinate system, so that the parameters of the reading signals of the associated multi-qubits are optimized, the accuracy of the measurement results is ensured, the multi-associated qubits can be applied, the practicability of the multi-associated qubits is improved, and the application scenarios of the multi-associated qubits are expanded. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0046] Figure 1 is a hardware structure block diagram of a computer terminal of a multi-qubit reading signal parameter optimization method provided by an embodiment of the present application;

[0047] Figure 2 is a structure schematic diagram of a superconducting quantum chip provided by an embodiment of the present application;

[0048] Figure 3 is a flowchart of a multi-qubit reading signal parameter optimization method provided by an embodiment of the present application;

[0049] Figure 4 is a structure schematic diagram of a 24-bit quantum chip provided by an embodiment of the present application;

[0050] Figure 5 is a distribution graph of an IQ coordinate system provided by an embodiment of the present application;

[0051] Figure 6 is a flowchart of a method for setting the parameters of the reading signals corresponding to each to-be-read qubit respectively provided by an embodiment of the present application;

[0052] Figure 7This is a flowchart illustrating a method for optimizing the parameters of the corresponding readout signal based on the distribution characteristics of the measurement data of each quantum bit to be read in the IQ coordinate system, according to an embodiment of the present invention.

[0053] Figure 8 This is a block diagram of a parameter optimization device for a multi-qubit readout signal provided in an embodiment of the present invention.

[0054] Explanation of reference numerals in the attached figures:

[0055] 102-Processor; 104-Memory; 106-Transmission device; 108-Input / output device; 510-Setting module; 520-Applying module; 530-Acquisition module; 540-Optimization module. Detailed Implementation

[0056] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a method, apparatus, and quantum computer for optimizing the parameters of a multi-qubit readout signal according to the present invention. The advantages and features of the present invention will become clearer from the following description. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0057] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0058] The method provided in this embodiment can be executed on a computer terminal or similar computing device. For example, to run on a computer terminal, please refer to [link to example]. Figure 1 A computer terminal may include one or more ( Figure 1 Only one is shown in the diagram. A processor 102 (which may include, but is not limited to, a microprocessor MCU or a programmable logic device FPGA, etc.) and a memory 104 for storing data are also shown. Optionally, the computer terminal may further include a transmission device 106 for communication functions and an input / output device 108. Those skilled in the art will understand that... Figure 1 The structure shown is for illustrative purposes only and does not limit the structure of the computer terminal described above. For example, the computer terminal may also include components that are more complex than those described above. Figure 1 The more or fewer components shown, or having the same Figure 1 The different configurations shown.

[0059] The memory 104 can be used to store software programs of application software and modules, such as program instructions / modules of a method for determining a multi-qubit measurement result provided in the present application. The processor 102 can execute various functional applications and data processing, i.e., implement the above method, by running the software programs and modules stored in the memory 104. The memory 104 can include a high-speed random access memory, and can also include a non-volatile solid-state memory. In some embodiments, the memory 104 can further include a memory 104 remotely arranged with respect to the processor 102, and these remote memories can be connected to the computer terminal through a network. Examples of the above network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0060] The transmission device 106 is used to receive or send data via a network. Specific examples of the above network can include an unlimited network provided by a communication provider of the computer terminal. In one embodiment, the transmission device includes a network adapter (Network Interface Controller, NIC), which can be connected to other network devices through a base station so as to communicate with the Internet. In one embodiment, the transmission device 106 can be a radio frequency (Radio Frequency, RF) module, which is used to communicate with the Internet in a wireless manner.

[0061] The method provided in the present embodiment can be applied to the above computer terminal, or a quantum computer.

[0062] In the quantum computer, the quantum chip is a processor for performing quantum computation. Please refer to Figure 2 The quantum chip is integrated with a plurality of one-to-one corresponding and mutually coupled quantum bits and read resonant cavities. Each read resonant cavity is connected to a read signal transmission line arranged integrally on the quantum chip away from a corresponding quantum bit. Each quantum bit is coupled and connected with an XY signal transmission line and a Z signal transmission line. The XY signal transmission line is used to receive a quantum state control signal. The Z signal transmission line is used to receive a magnetic flux control signal. The magnetic flux control signal includes a bias voltage signal and / or a pulse bias control signal. The bias voltage signal and the pulse bias control signal can both control the frequency of the quantum bit. The read signal transmission line is used to receive a read detection signal and emit a read feedback signal.

[0063] The control and processing process of the quantum bit is briefly described as follows:

[0064] The frequency of the quantum bit is adjusted to the working frequency by using the magnetic flux on the Z signal transmission line to regulate the signal. At this time, the quantum state of the quantum bit in the initial state is regulated by applying a quantum state regulating signal through the XY signal transmission line. The quantum state of the regulated quantum bit is read by using a reading resonant cavity. Specifically, a frequency pulse signal, usually referred to as a reading detection signal, is applied through the reading signal transmission line. The reading detection signal is usually a microwave signal with a frequency of 4-8 GHz. The quantum state of the quantum bit is determined by analyzing the reading feedback signal output by the reading signal transmission line. The fundamental reason why the reading resonant cavity can read the quantum state of the quantum bit is that different quantum states of the quantum bit produce different dispersion shifts of the reading resonant cavity, so that different quantum states of the quantum bit have different responses to the reading detection signal applied to the reading resonant cavity. The response signal is called a reading feedback signal. Only when the carrier frequency of the reading detection signal of the quantum bit is very close to the inherent frequency (also called the resonant frequency) of the reading resonant cavity, the reading resonant cavity will have a significant difference in response to the reading detection signal due to the different quantum states of the quantum bit, i.e. the reading feedback signal has the maximum distinguishability. Based on this, the quantum state of the quantum bit is determined by analyzing the reading feedback signal of a certain pulse length.

[0065] The core idea of the present application is to provide a multi-quantum bit reading signal parameter optimization method and device and a quantum computer. The parameters of the associated multi-quantum bit reading signal are optimized to ensure the accuracy of the measurement results, so that the multiple associated quantum bits can be applied, improving the practicality of the multiple associated quantum bits and expanding the application scenarios of the multiple associated quantum bits.

[0066] To this end, the present embodiment provides a multi-quantum bit reading signal parameter optimization method. A quantum chip is provided with a plurality of quantum bits arranged in sequence and a plurality of reading data buses. Each quantum bit is coupled to a plurality of reading data buses. Please refer to Figure 3 The parameter optimization method comprises the following steps:

[0067] Step S1: The parameters of the corresponding reading signal of each quantum bit to be read are set respectively.

[0068] The reading signal of the quantum bit to be read located on the same reading data bus is the same, and the reading signal is obtained by mixing the intermediate frequency signal. The intermediate frequency signal contains the modulation and coding information required for quantum computation of the quantum bit.

[0069] Specifically, the serial numbers of each quantum bit to be read and the number of quantum bits to be read are obtained first. This embodiment takes a 24-bit quantum chip as an example. Please refer to Figure 4The 24-bit quantum chip is provided with 24 quantum bits arranged in sequence and 4 data reading buses (BUS), the 24 quantum bits have the sequence as shown in Figure 4 The data reading bus BUS1 is coupled with quantum bits with sequence numbers 0-5, the data reading bus BUS2 is coupled with quantum bits with sequence numbers 6-11, the data reading bus BUS3 is coupled with quantum bits with sequence numbers 12-17, and the data reading bus BUS4 is coupled with quantum bits with sequence numbers 18-23. Based on the 24-bit quantum chip, for example, the number of quantum bits to be read is 3, the sequence numbers are 0, 1 and 17, and the quantum bits to be read are Q0, Q1 and Q17 respectively. 17 .

[0070] Specifically, as known from the above, the data reading buses corresponding to the two quantum bits to be read Q0 and Q1 are BUS1, and the reading signals are the same, the reading signal corresponding to the quantum bit to be read Q17 is applied to the data reading bus BUS3. 17 The parameters of the reading signals applied to the data reading buses BUS1 and BUS3 are set.

[0071] In step S2, the reading signals are respectively applied to the corresponding data reading buses to obtain corresponding reading feedback signals.

[0072] Specifically, in the embodiment, as known from the above, during the reading operation, the reading signals corresponding to the two quantum bits to be read Q0 and Q1 are applied to the data reading bus BUS1 to obtain corresponding reading feedback signals, and the reading signal corresponding to the quantum bit to be read Q17 is applied to the data reading bus BUS3 to obtain corresponding reading feedback signals. 17

[0073] In step S3, the measurement data of each quantum bit to be read is obtained based on the reading feedback signals.

[0074] Specifically, the reading feedback signals are analog signals representing the quantum state information of the quantum bits to be read coupled thereto. By applying different carrier frequency pulse signals (reading probe signals) to the corresponding quantum bits to be read and repeating the process, measurement data representing the quantum state information of each quantum bit can be obtained, and the measurement data is scatter point data in an IQ coordinate system.

[0075] In step S4, the parameters of the reading signals corresponding to each quantum bit to be read are optimized based on the distribution characteristics of the measurement data of each quantum bit to be read in the IQ coordinate system.

[0076] ​Theoretically, under ideal conditions, by applying different carrier frequency pulse signals (readout probe signals) to the corresponding qubits to be read and repeating this process, the resulting measurement data in the IQ coordinate system would be distributed as two circular spots, representing the two different ground states of the qubits to be read, specifically the |0> state and the |1> state. However, after numerous repeated experiments, it was found that during the measurement process, the distribution of the obtained measurement data in the IQ coordinate system is actually two roughly circular patterns. Please refer to [link to relevant documentation]. Figure 5 It can be observed that a small portion of the measurement data corresponding to the |0> state is distributed in the measurement data of the |1> state, and a small portion of the measurement data corresponding to the |1> state is distributed in the measurement data of the |0> state. This indicates that there is a disruption in the distribution of the quantum state of the qubit to be read in the experiment, and the parameters of the corresponding reading signal need to be optimized to make the distribution of the quantum state of the qubit to be read more ideal.

[0077] For example, please refer to Figure 6 The step of setting the parameters of the corresponding reading signal for each quantum bit to be read specifically includes:

[0078] Step S11: Determine the frequency of the read signal and preset the power of the read signal.

[0079] Specifically, when determining the frequency of the read signal, the read frequencies of all qubits coupled to each qubit to be read on the read data bus are obtained, and then the frequency of the corresponding read signal is determined based on the read frequencies of all qubits on the read data bus. More specifically, the median of the read frequencies of all qubits on the read data bus is determined, and then the median of the qubit read frequencies is set as the frequency of the read signal of the corresponding read data bus. For example, in this embodiment, the qubit to be read Q... 17 Taking the frequency setting of the corresponding readout signal as an example, firstly, obtain the quantum bit Q to be read. 17 The reading frequencies of all qubits coupled to the data bus (i.e., qubits numbered 12 to 17) are measured. These six reading frequencies are then arranged in numerical order, and the average of the two middle values ​​is taken as the value of the qubit to be read, Q. 17 The frequency of the corresponding read signal.

[0080] Step S12: Determine the frequency and amplitude of the intermediate frequency signal corresponding to the quantum bit to be read.

[0081] Specifically, when determining the frequency of the intermediate frequency signal corresponding to the to-be-read quantum bit respectively, the frequency of the intermediate frequency signal corresponding to the to-be-read quantum bit is determined based on a first preset relationship; wherein the frequency of the intermediate frequency signal corresponding to the to-be-read quantum bit, the frequency of the read signal, the read frequency corresponding to the to-be-read quantum bit and the preset frequency of the intermediate frequency signal satisfy the first preset relationship. More specifically, the first preset relationship is If'=Fc-Fc'+If, wherein If' is the frequency of the intermediate frequency signal corresponding to the to-be-read quantum bit, Fc is the frequency of the read signal, Fc' is the read frequency corresponding to the to-be-read quantum bit, and If is the preset frequency of the intermediate frequency signal.

[0082] Specifically, when determining the amplitude of the intermediate frequency signal corresponding to the to-be-read quantum bit respectively, the amplitude of the intermediate frequency signal corresponding to the to-be-read quantum bit is determined based on a second preset relationship; wherein the amplitude of the intermediate frequency signal corresponding to the to-be-read quantum bit, the preset amplitude of the intermediate frequency signal, the power of the read signal and the read power corresponding to the to-be-read quantum bit satisfy the second preset relationship. More specifically, the second preset relationship is Amp'=Amp×10^[(Pc'-10dB-Pc) / 2], wherein Amp' is the amplitude of the intermediate frequency signal corresponding to the to-be-read quantum bit, Amp is the read waveform amplitude corresponding to the to-be-read quantum bit, Pc' is the power of the read signal, and Pc is the read power corresponding to the to-be-read quantum bit.

[0083] For example, based on the distribution characteristics of the measurement data of each to-be-read quantum bit in the IQ coordinate system, the parameters of the read signal corresponding to each to-be-read quantum bit are optimized respectively, specifically including: Figure 7

[0084] Step S41, a criterion is established in the IQ coordinate system.

[0085] Preferably, the criterion is a straight line represented by I=Q in the IQ coordinate system, and the criterion is used to reflect the distribution characteristics of the measurement data of each to-be-read quantum bit in the IQ coordinate system.

[0086] Step S42, based on the criterion, it is judged whether the measurement data of each to-be-read quantum bit satisfies a preset condition respectively.

[0087] If not, step S43 is executed, and the parameters of the read signal corresponding to the to-be-read quantum bit are optimized respectively.

[0088] For example, the preset condition includes a first preset condition, and based on the criterion, it is judged whether the measurement data of each to-be-read quantum bit satisfies a preset condition respectively, if not, the parameters of the read signal corresponding to the to-be-read quantum bit are optimized respectively, specifically including: ​

[0089] determining whether the measurement data of each to-be-read quantum bit meets a first preset condition based on the criterion. The first preset condition is that the distribution of the measurement data obtained in the measurement process in the IQ coordinate system is two stable and clear circle-like shapes (i.e., two stable circle-like shapes) located on two sides of the criterion, respectively.

[0090] If no, the amplitude of the intermediate frequency signal corresponding to the to-be-read quantum bit is reduced in a preset range according to a preset step, and the read signal is updated. The amplitude of the intermediate frequency signal corresponding to each to-be-read quantum bit ranges from 0 to 1V.

[0091] Exemplarily, the preset condition further includes a second preset condition, and after determining whether the measurement data of each to-be-read quantum bit meets the first preset condition based on the criterion, the method further includes:

[0092] If yes, determining whether the measurement data of each to-be-read quantum bit meets a second preset condition based on the criterion. The second preset condition is that the distribution of the measurement data obtained in the measurement process in the IQ coordinate system is two circle-like shapes with no intersection of boundaries (i.e., two separate circle-like shapes) located on two sides of the criterion, respectively.

[0093] If no, the frequency of the intermediate frequency signal corresponding to the to-be-read quantum bit is reduced or increased in a preset range according to a preset step, and the read signal is updated.

[0094] Exemplarily, the preset condition further includes a third preset condition, and after determining whether the measurement data of each to-be-read quantum bit meets the second preset condition based on the criterion, the method further includes:

[0095] If yes, determining whether the measurement data of each to-be-read quantum bit meets a third preset condition based on the criterion. The third preset condition is that the distribution of the measurement data obtained in the measurement process in the IQ coordinate system is two circle-like shapes with high concentration (i.e., two circle-like shapes with high fidelity) located on two sides of the criterion, respectively.

[0096] If no, the frequency and / or amplitude of the intermediate frequency signal corresponding to the to-be-read quantum bit is reduced or increased in a preset range according to a preset step, and the read signal is updated.

[0097] Based on the same inventive concept, the embodiment provides a parameter optimization device for a read signal of a multi-quantum bit, please refer to Figure 8 , the parameter optimization device includes:

[0098] The setting module 510 is configured to set the parameters of the read signal corresponding to each to-be-read quantum bit based on the to-be-read quantum bit, respectively.

[0099] The application module 520 is configured to apply the read signal to the corresponding read data bus to obtain a corresponding read feedback signal.

[0100] The acquisition module 530 is configured to acquire measurement data of each quantum bit to be read based on the read feedback signal.

[0101] The optimization module 540 is configured to optimize the parameter of the read signal of each quantum bit to be read based on the distribution characteristics of the measurement data of the quantum bit to be read in the IQ coordinate system.

[0102] In addition, based on the same inventive concept, the embodiment further provides a quantum computer, which applies the parameter optimization method of the read signal of the multiple quantum bits or comprises the parameter optimization device of the read signal of the multiple quantum bits.

[0103] In summary, the parameter optimization method of the read signal of the multiple quantum bits, the parameter optimization device of the read signal of the multiple quantum bits and the quantum computer have the following advantages: when the parameter of the read signal of the multiple quantum bits is optimized, first, the parameter of the read signal corresponding to each quantum bit to be read is set based on each quantum bit to be read, then the read signal is applied to the corresponding read data bus to obtain the corresponding read feedback signal, and the measurement data of each quantum bit to be read is acquired based on the read feedback signal; the measurement data is the scatter data in the IQ coordinate system, and finally the parameter of the read signal corresponding to each quantum bit to be read is optimized based on the distribution characteristics of the measurement data of each quantum bit to be read in the IQ coordinate system, so that the parameter of the read signal of the associated multiple quantum bits is optimized, the accuracy of the measurement result is ensured, the multiple associated quantum bits can be applied, the practicability of the multiple associated quantum bits is improved, and the application scenarios of the multiple associated quantum bits are expanded.

[0104] The above description is only a description of the preferred embodiments of the application and does not limit the scope of the application. Any modification or change made by a person skilled in the art based on the above disclosure is within the protection scope of the claims.

Claims

1. A method for parameter optimization of a readout signal of a multi-qubit, wherein a plurality of qubits are arranged in sequence on a quantum chip, and a plurality of readout data buses are provided, and each readout data bus is coupled to a plurality of qubits, characterized in that, The parameter optimization method comprises: Parameters of the read signal corresponding to each to-be-read quantum bit are set respectively; the read signals of the to-be-read quantum bits located on the same read data bus are the same, the read signal is obtained by mixing a middle frequency signal, and the middle frequency signal contains modulation and coding information required by quantum bits for quantum computation; The read signal is applied to the corresponding read data bus to obtain a corresponding read feedback signal; Measurement data of each to-be-read quantum bit is obtained based on the read feedback signal; the measurement data is scatter data in an IQ coordinate system; Parameters of the read signal corresponding to each to-be-read quantum bit are set respectively; the read signals of the to-be-read quantum bits located on the same read data bus are the same, the read signal is obtained by mixing a middle frequency signal, and the middle frequency signal contains modulation and coding information required by quantum bits for quantum computation; 2. The method of claim 1, wherein, The frequency of the read signal is determined respectively, and the power of the read signal is preset; The frequency and amplitude of the middle frequency signal corresponding to the to-be-read quantum bit are determined respectively. The frequency of the read signal is determined respectively, and the power of the read signal is preset; 3. The method of claim 2, wherein, The read frequency of all quantum bits coupled and connected on the read data bus corresponding to each to-be-read quantum bit is obtained respectively; The frequency of the read signal corresponding to the read data bus is determined based on the read frequency of all quantum bits on the read data bus. The frequency of the read signal corresponding to the read data bus is determined based on the read frequency of all quantum bits on the read data bus.

4. The method of claim 3, wherein, The frequency of the read signal corresponding to the read data bus is determined based on the read frequency of all quantum bits on the read data bus. The frequency and amplitude of the middle frequency signal corresponding to the to-be-read quantum bit are determined respectively. The frequency of the middle frequency signal corresponding to the to-be-read quantum bit is determined based on a first preset relationship; the frequency of the middle frequency signal corresponding to the to-be-read quantum bit, the frequency of the read signal, the read frequency of the corresponding to-be-read quantum bit and the preset frequency of the middle frequency signal satisfy the first preset relationship; 5. The method of claim 2, wherein the plurality of qubits are read out by a single readout signal. The amplitude of the middle frequency signal corresponding to the to-be-read quantum bit is determined based on a second preset relationship; the amplitude of the middle frequency signal corresponding to the to-be-read quantum bit, the preset amplitude of the middle frequency signal, the power of the read signal and the read power of the corresponding to-be-read quantum bit satisfy the second preset relationship. The first preset relationship is If'=Fc-Fc'+If, wherein If' is the frequency of the middle frequency signal corresponding to the to-be-read quantum bit, Fc is the frequency of the read signal, Fc' is the read frequency of the corresponding to-be-read quantum bit, and If is the preset frequency of the middle frequency signal. The second preset relationship is Amp'=Amp×10^[(Pc'-10dB-Pc) / 2], wherein Amp' is the amplitude of the middle frequency signal corresponding to the to-be-read quantum bit, Amp is the preset amplitude of the middle frequency signal, Pc' is the power of the read signal, and Pc is the read power of the corresponding to-be-read quantum bit.

6. The method of claim 5, wherein, ​ ​ 7. The method of claim 5, wherein the plurality of qubits are read out by a single readout signal. ​ ​ 8. The method of claim 2, wherein, The parameters of the reading signals corresponding to the to-be-read quantum bits are respectively optimized based on the distribution characteristics of the measurement data of the to-be-read quantum bits in the IQ coordinate system, specifically including: a criterion is established in the IQ coordinate system, wherein the criterion is used to reflect the distribution characteristics of the measurement data of the to-be-read quantum bits in the IQ coordinate system; whether the measurement data of each to-be-read quantum bit meets the preset condition is judged based on the criterion, and if not, the parameters of the reading signals corresponding to the to-be-read quantum bits are respectively optimized.

9. The method of claim 8, wherein, The preset condition includes a first preset condition, and the method of optimizing the parameters of the reading signals of the multi-quantum bits includes: whether the measurement data of each to-be-read quantum bit meets the first preset condition is judged based on the criterion; if not, the amplitude of the intermediate frequency signal corresponding to the to-be-read quantum bit is reduced in a preset range according to a preset step, and the reading signal is updated.

10. The method of claim 9, wherein, The preset condition also includes a second preset condition, and after judging whether the measurement data of each to-be-read quantum bit meets the first preset condition based on the criterion, the method of optimizing the parameters of the reading signals of the multi-quantum bits includes: if yes, whether the measurement data of each to-be-read quantum bit meets the second preset condition is judged based on the criterion; if not, the frequency of the intermediate frequency signal corresponding to the to-be-read quantum bit is reduced or increased in a preset range according to a preset step, and the reading signal is updated.

11. The method of claim 10, wherein, The preset condition also includes a third preset condition, and after judging whether the measurement data of each to-be-read quantum bit meets the second preset condition based on the criterion, the method of optimizing the parameters of the reading signals of the multi-quantum bits includes: if yes, whether the measurement data of each to-be-read quantum bit meets the third preset condition is judged based on the criterion; if not, the frequency and / or amplitude of the intermediate frequency signal corresponding to the to-be-read quantum bit is reduced or increased in a preset range according to a preset step, and the reading signal is updated.

12. A parameter optimization device of a read signal of a multi-qubit, characterized by, The method includes: a setting module for setting the parameters of the reading signals corresponding to each to-be-read quantum bit; an applying module for applying the reading signals to the corresponding reading data bus to obtain corresponding reading feedback signals; an obtaining module for obtaining the measurement data of each to-be-read quantum bit based on the reading feedback signals; an optimization module for optimizing the parameters of the reading signals corresponding to each to-be-read quantum bit based on the distribution characteristics of the measurement data of the to-be-read quantum bits in the IQ coordinate system.

13. A quantum computer, comprising: The method of optimizing the parameters of the reading signals of the multi-quantum bits according to any one of claims 1-11 is used to optimize the parameters of the reading signals of the multi-quantum bits, or the parameter optimization device of the multi-quantum bits according to claim 12 is included.

Images