A superconducting quantum bit quantum state reading method, device, equipment and medium

Abstract

The present application relates to the field of quantum bit reading, in particular to a superconducting quantum bit quantum state reading method, device, equipment and medium, a reading driving signal is sent to a superconducting quantum chip; The reading driving signal is a variable frequency signal comprising the |0> state resonance frequency and the |1> state resonance frequency of the superconducting quantum bit; The reading feedback signal is collected from the superconducting quantum chip; According to the reading feedback signal, the pre-stored |0> state response signal and |1> state response signal corresponding to the reading driving signal, the quantum state of the superconducting quantum bit is determined by correlation analysis. The present application uses a variable frequency signal as the reading driving signal, which can reduce the sensitivity of the system to frequency-independent noise, improve the signal-to-noise ratio of the signal, and the correlation calculation does not need to be converted to the IQ plane, reducing the calculation steps, and the correlation analysis algorithm can usually use hardware acceleration, reducing the resource consumption of the solution, improving the operation efficiency.

Description

Technical Field

[0001] This invention relates to the field of quantum bit readout, and in particular to a method, apparatus, device, and medium for reading out the quantum state of a superconducting quantum bit. Background Technology

[0002] Reading the quantum state of a qubit is one of the key steps in realizing quantum computing. In superconducting quantum computers, the basic principle of reading the quantum state of a qubit lies in measuring the frequency response of the coupling system between the resonant cavity and the qubit. When the qubit is in different states, the resonant frequency of this coupling system will shift slightly. By distinguishing the effect of this change on the frequency response, the eigenstate of the qubit can be indirectly obtained.

[0003] Existing superconducting quantum bit readout methods generally employ a fixed-frequency driving signal, typically within the resonant frequency offset range of the resonant cavity. The solution process involves converting the signal to the IQ (real / imaginary) domain and performing state resolution on the IQ plane. However, computation on the IQ plane is computationally expensive, time-consuming, and prone to interference. Currently, solutions from various companies and research institutions primarily focus on hardware system improvements, using different electronic components to enhance the signal-to-noise ratio of the readout feedback signal and improve computational efficiency. However, the effects of noise removal and efficiency improvement are unsatisfactory, and the costs are excessively high.

[0004] Therefore, how to improve computing efficiency while increasing the signal-to-noise ratio at a lower cost has become a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a method, apparatus, device, and medium for reading out the quantum state of a superconducting quantum bit, so as to solve the problem that existing technologies cannot improve computational efficiency and signal-to-noise ratio at a lower cost.

[0006] To address the aforementioned technical problems, this invention provides a method for reading the quantum state of a superconducting quantum bit, comprising:

[0007] Send a readout drive signal to the superconducting quantum chip; the readout drive signal is a frequency-converted signal that includes the resonant frequencies of the |0> state and the |1> state of the superconducting quantum bit;

[0008] The feedback signal is acquired and read from the superconducting quantum chip;

[0009] The quantum state of the superconducting quantum bit is determined by correlation analysis based on the read feedback signal, the pre-stored |0> state response signal and |1> state response signal corresponding to the read drive signal.

[0010] Optionally, in the superconducting quantum bit quantum state readout method, determining the quantum state of the superconducting quantum bit through correlation analysis based on the readout feedback signal, the pre-stored |0> state response signal and |1> state response signal corresponding to the readout drive signal, includes:

[0011] Calculate the |0> state correlation between the |0> state response signal and the read feedback signal;

[0012] Calculate the |1> state correlation between the |1> state response signal and the read feedback signal;

[0013] The quantum state of the superconducting quantum bit is determined by comparing the correlation between the |0> state and the |1> state.

[0014] Optionally, in the superconducting quantum bit quantum state readout method, determining the quantum state of the superconducting quantum bit by comparing the magnitudes of the |0> state correlation and the |1> state correlation includes:

[0015] The temporary variable is determined by the following formula:

[0016] p = C(w) |1> ,w back )-C(w |0> ,w back );

[0017] Where p is a temporary variable, C(w) |1> ,w back ) represents the state correlation of |1>, C(w) |0> ,w back ) represents the correlation of the state |0>.

[0018] Determine whether the temporary variable is greater than 0;

[0019] When the temporary variable is greater than 0, the quantum bit is determined to be in the |1> state;

[0020] When the temporary variable is less than or equal to 0, the quantum bit is determined to be in the |0> state.

[0021] Optionally, in the superconducting quantum bit quantum state readout method, sending the readout drive signal to the superconducting quantum chip includes:

[0022] Send a chirped drive signal to the superconducting quantum chip, the amplitude of which varies with time as follows:

[0023]

[0024] Where w is the signal amplitude, T is the pulse width, A(t) is the pulse window function, and f |0>f is the resonant frequency of the |0> state. |1> The resonant frequency of the |1> state.

[0025] Optionally, in the superconducting quantum bit quantum state readout method, sending the readout drive signal to the superconducting quantum chip includes:

[0026] A transient driving signal whose amplitude varies with time is sent to the superconducting quantum chip as follows:

[0027]

[0028] Where w is the signal amplitude, T is the pulse width, A(t) is the pulse window function, and f |0> f is the resonant frequency of the |0> state. |1> The resonant frequency of the |1> state.

[0029] Optionally, in the superconducting quantum bit quantum state readout method, sending the readout drive signal to the superconducting quantum chip includes:

[0030] A repetitive driving signal with an amplitude that varies with time is sent to the superconducting quantum chip as follows:

[0031]

[0032] Where w is the signal amplitude, T is the pulse width, A(t) is the pulse window function, and f |0> f is the resonant frequency of the |0> state. |1> The resonant frequency of the |1> state.

[0033] A superconducting quantum bit quantum state readout device, comprising:

[0034] The transmitting module is used to send a read drive signal to the superconducting quantum chip; the read drive signal is a frequency-converted signal including the resonant frequency of the |0> state and the resonant frequency of the |1> state of the superconducting quantum bit;

[0035] The acquisition module is used to acquire and read feedback signals from the superconducting quantum chip;

[0036] The correlation module is used to determine the quantum state of the superconducting quantum bit through correlation analysis based on the read feedback signal, the pre-stored |0> state response signal and |1> state response signal corresponding to the read drive signal.

[0037] Optionally, in the superconducting quantum bit quantum state readout device, the correlation module includes:

[0038] The |0> state correlation unit is used to calculate the |0> state correlation between the |0> state response signal and the read feedback signal;

[0039] The |1> state correlation unit is used to calculate the |1> state correlation between the |1> state response signal and the read feedback signal;

[0040] A comparison unit is used to compare the magnitude of the correlation between the |0> state and the |1> state to determine the quantum state of the superconducting quantum bit.

[0041] A superconducting quantum bit quantum state readout device, characterized in that it comprises:

[0042] Memory, used to store computer programs;

[0043] A processor for executing the computer program to implement the steps of the superconducting quantum bit quantum state readout method as described above.

[0044] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the superconducting quantum bit quantum state readout method as described above.

[0045] The superconducting quantum bit quantum state readout method provided by this invention involves sending a readout drive signal to a superconducting quantum chip; the readout drive signal is a frequency-converted signal including the resonant frequencies of the |0> and |1> states of the superconducting quantum bit; acquiring a readout feedback signal from the superconducting quantum chip; and determining the quantum state of the superconducting quantum bit through correlation analysis based on the readout feedback signal and pre-stored |0> and |1> state response signals corresponding to the readout drive signal. This invention uses a frequency-converted signal as the readout drive signal, which reduces the system's sensitivity to frequency-independent noise and improves the signal-to-noise ratio. Furthermore, since the correlation calculation does not need to be converted to the IQ plane but is performed directly in the time domain based on the correlation, it fully utilizes the data within the entire pulse time period and reduces the number of calculation steps. Moreover, the correlation analysis algorithm can usually be hardware-accelerated, further reducing the resource consumption of the solution and improving computational efficiency. This invention also provides a superconducting quantum bit quantum state readout device, apparatus, and medium with the above-mentioned beneficial effects. Attached Figure Description

[0046] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1A flowchart illustrating a specific implementation of the superconducting quantum bit quantum state readout method provided by the present invention;

[0048] Figure 2 A schematic diagram of the readout drive signal for a specific embodiment of the superconducting quantum bit quantum state readout method provided by the present invention;

[0049] Figure 3 A schematic diagram of the readout driving signal for another specific embodiment of the superconducting quantum bit quantum state readout method provided by the present invention;

[0050] Figure 4 A schematic diagram of the readout driving signal for another specific embodiment of the superconducting quantum bit quantum state readout method provided by the present invention;

[0051] Figure 5 A hardware schematic diagram of a superconducting quantum bit quantum state readout system corresponding to a specific embodiment of the superconducting quantum bit quantum state readout method provided by the present invention;

[0052] Figure 6 The quantum state readout signal flow graph in the digital device of the test system corresponding to a specific embodiment of the superconducting quantum bit quantum state readout method provided by the present invention;

[0053] Figure 7 A flowchart illustrating another specific embodiment of the superconducting quantum bit quantum state readout method provided by the present invention;

[0054] Figure 8 This is a schematic diagram of a specific embodiment of the superconducting quantum bit quantum state readout device provided by the present invention.

[0055] The diagram includes: 100 - Transmitting module; 200 - Acquisition module; 300 - Correlation module; 210 - Digital device; 220 - Digital-to-analog conversion and processing channel; 110 - Processing and analog-to-digital conversion channel, measurement and control system; 120 - Reading drive signal transmission channel; 130 - Reading feedback signal transmission channel; 140 - Superconducting quantum chip; 710 - Reading drive digital signal; 720 - Reading feedback acquisition digital signal; 730 - Reading drive radio frequency signal; 740 - Reading feedback radio frequency signal; 750 - Signal input to the input port of the superconducting quantum chip read line; 760 - Signal flowing out from the output port of the superconducting quantum chip read line; 770 - Quantum state reading result of superconducting quantum bit; 310 - Reading drive signal; 320 - |0> state response signal; 330 - |1> state response signal; 410 - Generation unit; 420 - Solving unit. Detailed Implementation

[0056] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] The core of this invention is to provide a method for reading the quantum state of a superconducting quantum bit, and a flowchart of one specific implementation is shown below. Figure 1 As shown, this is referred to as Specific Implementation Method One, which includes:

[0058] S101: Send a read drive signal to the superconducting quantum chip; the read drive signal is a frequency conversion signal including the resonant frequency of the |0> state and the resonant frequency of the |1> state of the superconducting quantum bit.

[0059] The basic principle of superconducting quantum bit readout is that when a superconducting quantum bit is in different quantum states, the resonant frequency of the resonant cavity coupled with it will be shifted to a certain extent, thereby causing the resonant cavity to have a significant change in the signal response within the resonant frequency shift range. The readout driving signal is the signal sent to the resonant cavity.

[0060] In this step, sending the readout drive signal to the superconducting quantum chip includes:

[0061] A chirped drive signal with an amplitude varying with time as shown in equation (1) is sent to the superconducting quantum chip:

[0062]

[0063] Where w is the signal amplitude, T is the pulse width, and A(t) is the window function of the pulse.

[0064] In this preferred embodiment, the read drive signal is set as a chirp signal, which is a signal linearly frequency-modulated from the resonant frequency of the |0> state and the resonant frequency of the |1> state. The corresponding signal diagram is shown in the figure below. Figure 2 As shown, chirped signal modulation is simple, versatile, and fast, which can improve the speed of quantum state readout of superconducting qubits.

[0065] Of course, the read drive signal can also be a signal other than a chirp signal. As another specific implementation, a transient drive signal whose amplitude varies with time as shown in equation (2) is sent to the superconducting quantum chip:

[0066]

[0067] Where w is the signal amplitude, T is the pulse width, and A(t) is the window function of the pulse. The corresponding signal diagram is shown in Figure 1. Figure 3 As shown, in the transient drive signal, the frequencies of all time periods are occupied by the resonant frequencies of the |0> state and the |1> state, providing more effective judgment information. Therefore, in subsequent steps, the correlation between the read feedback signal and the response signals of the |0> state and the response signals of the |1> state will not be very low, which would lead to unreliable judgment results.

[0068] Furthermore, as another specific implementation, a repetitive driving signal with an amplitude varying with time as shown in equation (3) is sent to the superconducting quantum chip:

[0069]

[0070] Where w is the signal amplitude, T is the pulse width, and A(t) is the window function of the pulse. The corresponding signal diagram is shown in Figure 1. Figure 4 As shown, the repeated driving signal provides a longer frequency variation, which can further improve the accuracy of subsequent correlation judgment.

[0071] S102: Collect and read feedback signals from the superconducting quantum chip.

[0072] The read feedback signal is the signal returned after the read drive signal passes through the resonant cavity, which includes the resonance information of the resonant cavity. The quantum state of the superconducting quantum bit can be inferred based on the read feedback signal.

[0073] S103: Based on the read feedback signal, the pre-stored |0> state response signal and |1> state response signal corresponding to the read drive signal, the quantum state of the superconducting quantum bit is determined by correlation analysis.

[0074] In this step, correlation analysis is used. Specifically, the correlation between the |0> state response signal and the read feedback signal is compared with the correlation between the |1> state response signal and the read feedback signal to determine the quantum state of the superconducting quantum bit. In addition, a correlation lower limit can be set. That is, the superconducting quantum bit is determined to be the corresponding quantum state only when the correlation between the read feedback signal and the |0> state response signal or the |1> state response signal is greater than the correlation lower limit. If neither correlation exceeds the correlation lower limit, the read drive signal is resent to obtain a new read feedback signal, and the quantum state of the superconducting quantum bit is determined based on the new read feedback signal.

[0075] Please refer to Figure 5 , Figure 5This is a hardware diagram of a superconducting quantum bit quantum state readout system, including digital devices 210 in the test system, a digital-to-analog conversion and processing channel 220 for the readout drive signal in the measurement and control system, a processing and analog-to-digital conversion channel for the readout feedback signal in the measurement and control system 110, a readout drive signal transmission channel 120 including electronic cables and electronic devices such as attenuators and filters for different temperature zones, a readout feedback signal transmission channel 130 including electronic cables and electronic devices such as isolators and amplifiers for different temperature zones, a superconducting quantum chip 140, a readout drive digital signal 710, a readout feedback acquisition digital signal 720, a readout drive radio frequency signal 730, a readout feedback radio frequency signal 740, a signal 750 input to the input port of the superconducting quantum chip readout line, a signal 760 flowing out from the output port of the superconducting quantum chip readout line, and the quantum state readout result of the superconducting quantum bit 770.

[0076] Please refer to Figure 6 , Figure 6 The test system includes a quantum state readout signal flow graph in digital device 210, a readout drive signal 310, a pre-calibrated |0> state response signal 320 corresponding to the |0> state of the qubit, a pre-calibrated |1> state response signal 330 corresponding to the |1> state of the qubit, a readout drive signal generation unit 410, and a readout feedback signal calculation unit 420.

[0077] The superconducting quantum bit quantum state readout method provided by this invention involves sending a readout drive signal to a superconducting quantum chip; the readout drive signal is a frequency-converted signal including the resonant frequencies of the |0> and |1> states of the superconducting quantum bit; acquiring a readout feedback signal from the superconducting quantum chip; and determining the quantum state of the superconducting quantum bit through correlation analysis based on the readout feedback signal and pre-stored |0> and |1> state response signals corresponding to the readout drive signal. This invention uses a frequency-converted signal as the readout drive signal, which reduces the system's sensitivity to frequency-independent noise and improves the signal-to-noise ratio. Furthermore, since the correlation calculation does not need to be converted to the IQ plane but is performed directly in the time domain based on the correlation, it fully utilizes the data within the entire pulse time period, reduces the computational steps, and the correlation analysis algorithm can usually be hardware-accelerated, further reducing computational resource consumption and improving computational efficiency.

[0078] Based on Implementation Method 1, the correlation calculation process is further defined to obtain Implementation Method 2, the flowchart of which is shown below. Figure 7 As shown, it includes:

[0079] S201: Send a read drive signal to the superconducting quantum chip; the read drive signal is a frequency conversion signal including the resonant frequency of the |0> state and the resonant frequency of the |1> state of the superconducting quantum bit.

[0080] S202: Collect and read feedback signals from the superconducting quantum chip.

[0081] S203: Calculate the |0> state correlation between the |0> state response signal and the read feedback signal.

[0082] The |0> state correlation refers to the correlation between the |0> state response signal and the read feedback signal.

[0083] S204: Calculate the |1> state correlation between the |1> state response signal and the read feedback signal.

[0084] The |1> state correlation is the correlation between the |1> state response signal and the read feedback signal.

[0085] It should be noted that there is no strict order between steps S203 and S204, and their order can be interchanged at will.

[0086] S205: Compare the magnitudes of the correlation between the |0> state and the |1> state to determine the quantum state of the superconducting quantum bit.

[0087] Furthermore, determining the quantum state of the superconducting quantum bit by comparing the correlation between the |0> state and the |1> state includes:

[0088] A1: The temporary variable is determined by the following formula (4):

[0089] p = C(w) |1> ,w back )-C(w |0> ,w back );......(4)

[0090] Where p is a temporary variable, C(w) |1> ,w back ) represents the state correlation of |1>, C(w) |0> ,w back ) represents the state correlation of |0>.

[0091] A2: Determine whether the temporary variable is greater than 0.

[0092] A3: When the temporary variable is greater than 0, the quantum bit is determined to be in the |1> state.

[0093] A4: When the temporary variable is less than or equal to 0, the quantum bit is determined to be in the |0> state.

[0094] Steps A3 and A4 are simply operations corresponding to the two scenarios following the judgment in step A2, and therefore there is no strict sequential relationship. Of course, the two terms in equation (4) can also be interchanged. In this case, if the temporary variable is greater than 0, the quantum bit is determined to be in the |0> state; if the temporary variable is less than or equal to 0, the quantum bit is determined to be in the |1> state. By calculating the difference between the two correlations using equation (4), the quantum state can be determined with relatively little computing power, improving computational efficiency and shortening computation time.

[0095] The difference between this specific embodiment and the above specific embodiment is that the calculation process of the correlation is further improved in this specific embodiment, while the remaining steps are the same as those in the above specific embodiment, and will not be elaborated here.

[0096] In this specific embodiment, a method for determining the quantum state of a superconducting quantum bit through correlation is provided. That is, the correlation between the returned readout response signal and the response signal of the |0> state and the response signal of the |1> state are calculated respectively, and the magnitudes of the two correlations are compared. The one with stronger correlation is used to determine the quantum state of the superconducting quantum bit.

[0097] Since noise is often independent of quantum states, when calculating correlation analysis, the noise component in the signal is correlated with the |0> state response signal and the |1> state response signal, while the signal component containing the quantum state will be significantly different. Comparing the magnitudes of the two correlations can effectively cancel out the influence of noise and further improve the accuracy of reading the quantum state of superconducting qubits.

[0098] The superconducting quantum bit quantum state reading device provided in the embodiments of the present invention is described below. The superconducting quantum bit quantum state reading device described below can be referred to in correspondence with the superconducting quantum bit quantum state reading method described above.

[0099] Figure 8 The structural block diagram of the superconducting quantum bit quantum state readout device provided in this embodiment of the invention is referred to as Specific Embodiment Three, and is referred to as follows. Figure 8 A superconducting quantum bit quantum state readout device may include:

[0100] The transmitting module 100 is used to send a read drive signal to the superconducting quantum chip; the read drive signal is a frequency conversion signal including the resonant frequency of the |0> state and the resonant frequency of the |1> state of the superconducting quantum bit;

[0101] Acquisition module 200 is used to acquire and read feedback signals from the superconducting quantum chip;

[0102] The correlation module 300 is used to determine the quantum state of the superconducting quantum bit through correlation analysis based on the read feedback signal, the pre-stored |0> state response signal and |1> state response signal corresponding to the read drive signal.

[0103] In a preferred embodiment, the correlation module 300 includes:

[0104] The |0> state correlation unit is used to calculate the |0> state correlation between the |0> state response signal and the read feedback signal;

[0105] The |1> state correlation unit is used to calculate the |1> state correlation between the |1> state response signal and the read feedback signal;

[0106] A comparison unit is used to compare the magnitude of the correlation between the |0> state and the |1> state to determine the quantum state of the superconducting quantum bit.

[0107] In a preferred embodiment, the correlation module 300 includes:

[0108] The temporary variable unit is used to determine the temporary variable by the following formula:

[0109] p = C(w) |1> ,w back )-C(w |0> ,w back );

[0110] Where p is a temporary variable, C(w) |1> ,w back ) represents the state correlation of |1>, C(w) |0> ,w back ) represents the correlation of the state |0>.

[0111] A judgment unit is used to determine whether the temporary variable is greater than 0;

[0112] The |1> state determination unit is used to determine that the quantum bit is in the |1> state when the temporary variable is greater than 0;

[0113] The |0> state determination unit is used to determine that the quantum bit is in the |0> state when the temporary variable is less than or equal to 0.

[0114] In a preferred embodiment, the transmitting module 100 includes:

[0115] The chirped transmitting unit is used to send a chirped driving signal to the superconducting quantum chip, the amplitude of which varies with time as follows:

[0116]

[0117] Where w is the signal amplitude, T is the pulse width, A(t) is the pulse window function, and f |0> f is the resonant frequency of the |0> state. |1> The resonant frequency of the |1> state.

[0118] In a preferred embodiment, the sending module 100 includes:

[0119] The transient transmission unit is used to send transient drive signals to the superconducting quantum chip, the amplitude of which varies with time as follows:

[0120]

[0121] Where w is the signal amplitude, T is the pulse width, A(t) is the pulse window function, and f |0> f is the resonant frequency of the |0> state. |1> The resonant frequency of the |1> state.

[0122] In a preferred embodiment, the sending module 100 includes:

[0123] The repetitive transmission unit is used to send repetitive driving signals to the superconducting quantum chip, the amplitude of which varies with time as follows:

[0124]

[0125] Where w is the signal amplitude, T is the pulse width, A(t) is the pulse window function, and f |0> f is the resonant frequency of the |0> state. |1> The resonant frequency of the |1> state.

[0126] The superconducting quantum bit quantum state readout device provided by this invention includes a transmitting module 100 for sending a readout drive signal to a superconducting quantum chip; the readout drive signal is a frequency-converted signal including the resonant frequencies of the |0> and |1> states of the superconducting quantum bit; an acquisition module 200 for acquiring a readout feedback signal from the superconducting quantum chip; and a correlation module 300 for determining the quantum state of the superconducting quantum bit through correlation analysis based on the readout feedback signal and pre-stored |0> and |1> state response signals corresponding to the readout drive signal. This invention uses a frequency-converted signal as the readout drive signal, which reduces the system's sensitivity to frequency-independent noise and improves the signal-to-noise ratio. Furthermore, since the correlation calculation does not need to be converted to the IQ plane but is performed directly in the time domain based on the correlation, it fully utilizes the data within the entire pulse time period, reduces the computational steps, and the correlation analysis algorithm can usually be hardware-accelerated, further reducing computational resource consumption and improving computational efficiency.

[0127] The superconducting quantum bit quantum state reading device of this embodiment is used to implement the aforementioned superconducting quantum bit quantum state reading method. Therefore, the specific implementation of the superconducting quantum bit quantum state reading device can be found in the embodiment section of the superconducting quantum bit quantum state reading method above. For example, the transmitting module 100, the acquiring module 200, and the correlation module 300 are used to implement steps S101, S102, S103, and S104 in the superconducting quantum bit quantum state reading method, respectively. Therefore, the specific implementation can be referred to the description of the corresponding embodiments, which will not be repeated here.

[0128] The present invention also provides a superconducting quantum bit quantum state readout device, characterized in that it comprises:

[0129] Memory, used to store computer programs;

[0130] A processor is configured to execute the computer program to implement the steps of the superconducting quantum bit quantum state readout method as described above. The superconducting quantum bit quantum state readout method provided by this invention involves sending a readout drive signal to a superconducting quantum chip; the readout drive signal is a frequency-converted signal including the resonant frequencies of the |0> and |1> states of the superconducting quantum bit; acquiring a readout feedback signal from the superconducting quantum chip; and determining the quantum state of the superconducting quantum bit through correlation analysis based on the readout feedback signal and pre-stored |0> and |1> state response signals corresponding to the readout drive signal. This invention uses a frequency-converted signal as the readout drive signal, which reduces the system's sensitivity to frequency-independent noise and improves the signal-to-noise ratio. Furthermore, since the correlation calculation does not need to be converted to the IQ plane but is performed directly in the time domain based on the correlation, it fully utilizes the data within the entire pulse time period, reduces the number of calculation steps, and the correlation analysis algorithm can usually be hardware-accelerated, further reducing the resource consumption of the solution and improving computational efficiency.

[0131] This invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the superconducting quantum bit quantum state readout method as described above. The superconducting quantum bit quantum state readout method provided by this invention involves sending a readout drive signal to a superconducting quantum chip; the readout drive signal being a frequency-converted signal including the resonant frequencies of the |0> and |1> states of the superconducting quantum bit; acquiring a readout feedback signal from the superconducting quantum chip; and determining the quantum state of the superconducting quantum bit through correlation analysis based on the readout feedback signal and pre-stored |0> and |1> state response signals corresponding to the readout drive signal. This invention uses a frequency-converted signal as the readout drive signal, which reduces the system's sensitivity to frequency-independent noise and improves the signal-to-noise ratio. Furthermore, since the correlation calculation does not need to be converted to the IQ plane but is performed directly in the time domain based on the correlation, it fully utilizes the data within the entire pulse time period, reduces the number of calculation steps, and the correlation analysis algorithm can usually be hardware-accelerated, further reducing the resource consumption of the solution and improving computational efficiency.

[0132] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0133] It should be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0134] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0135] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0136] The superconducting quantum bit quantum state readout method, apparatus, device, and medium provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A method for reading the quantum state of a superconducting quantum bit, characterized in that, include: Send a readout drive signal to the superconducting quantum chip; the readout drive signal is a frequency-converted signal that includes the resonant frequencies of the |0> state and the |1> state of the superconducting quantum bit; The feedback signal is acquired and read from the superconducting quantum chip; Based on the read feedback signal, the pre-stored |0> state response signal and |1> state response signal corresponding to the read drive signal, the quantum state of the superconducting quantum bit is determined by correlation analysis; The step of determining the quantum state of the superconducting quantum bit through correlation analysis based on the read feedback signal, the pre-stored |0> state response signal and |1> state response signal corresponding to the read drive signal, includes: Calculate the |0> state correlation between the |0> state response signal and the read feedback signal; Calculate the |1> state correlation between the |1> state response signal and the read feedback signal; The quantum state of the superconducting quantum bit is determined by comparing the correlation between the |0> state and the |1> state.

2. The method for reading out the quantum state of a superconducting quantum bit as described in claim 1, characterized in that, The step of comparing the correlation between the |0> state and the |1> state to determine the quantum state of the superconducting quantum bit includes: The temporary variable is determined by the following formula: ； Where p is a temporary variable, C(w) |1> ,w back ) represents the state correlation of |1>, C(w) |0> ,w back ) represents the correlation of the state |0>. Determine whether the temporary variable is greater than 0; When the temporary variable is greater than 0, the quantum bit is determined to be in the |1> state; When the temporary variable is less than or equal to 0, the quantum bit is determined to be in the |0> state.

3. The method for reading out the quantum state of a superconducting quantum bit as described in claim 1, characterized in that, Sending the readout drive signal to the superconducting quantum chip includes: Send a chirped drive signal to the superconducting quantum chip, the amplitude of which varies with time as follows: ； Where w is the signal amplitude, T is the pulse width, A(t) is the pulse window function, and f |0> f is the resonant frequency of the |0> state. |1> The resonant frequency of the |1> state.

4. The method for reading out the quantum state of a superconducting quantum bit as described in claim 1, characterized in that, Sending the readout drive signal to the superconducting quantum chip includes: A transient driving signal whose amplitude varies with time is sent to the superconducting quantum chip as follows: ； Where w is the signal amplitude, T is the pulse width, A(t) is the pulse window function, and f |0> f is the resonant frequency of the |0> state. |1> The resonant frequency of the |1> state.

5. The method for reading out the quantum state of a superconducting quantum bit as described in claim 1, characterized in that, Sending the readout drive signal to the superconducting quantum chip includes: A repetitive driving signal with an amplitude that varies with time is sent to the superconducting quantum chip as follows: ； Where w is the signal amplitude, T is the pulse width, A(t) is the pulse window function, and f |0> f is the resonant frequency of the |0> state. |1> The resonant frequency of the |1> state.

6. A superconducting quantum bit quantum state readout device, characterized in that, include: The transmitting module is used to send a read drive signal to the superconducting quantum chip; the read drive signal is a frequency-converted signal including the resonant frequency of the |0> state and the resonant frequency of the |1> state of the superconducting quantum bit; The acquisition module is used to acquire and read feedback signals from the superconducting quantum chip; The correlation module is used to determine the quantum state of the superconducting quantum bit through correlation analysis based on the read feedback signal, the pre-stored |0> state response signal and |1> state response signal corresponding to the read drive signal; The correlation module includes: The |0> state correlation unit is used to calculate the |0> state correlation between the |0> state response signal and the read feedback signal; The |1> state correlation unit is used to calculate the |1> state correlation between the |1> state response signal and the read feedback signal; A comparison unit is used to compare the magnitude of the correlation between the |0> state and the |1> state to determine the quantum state of the superconducting quantum bit.

7. A superconducting quantum bit quantum state readout device, characterized in that, include: Memory, used to store computer programs; A processor, configured to implement the steps of the superconducting quantum bit quantum state readout method as described in any one of claims 1 to 5 when executing the computer program.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the superconducting quantum bit quantum state readout method as described in any one of claims 1 to 5.

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