Quantum gate de-coherence error determination method and device, computer equipment, medium and product

Abstract

The invention relates to a quantum gate de-coherence error determination method and device, computer equipment, a medium and a product. The method comprises the steps of applying a first Z pulse to a quantum bit, applying a first virtual Z gate to the quantum bit after the first Z pulse to construct a first idle gate corresponding to a first preset frequency, for each gate sequence, arranging each quantum gate in the gate sequence and the first idle gate in a staggered manner to obtain a first target gate sequence, and based on each first target gate sequence, constructing a second target gate sequence, and determining a first parameter related to the quantum gate operation average error in the interleaved random benchmark test corresponding to the first free gate. The quantum gate decoherence error corresponding to the first preset frequency is determined based on the first parameter and the second parameter related to the quantum gate operation average error in the standard random benchmark test, so that the time required for determining the quantum gate decoherence error is saved, and the determination efficiency of the quantum gate decoherence error is improved.

Description

Technical Field

[0001] This application relates to the field of quantum computing technology, and in particular to a method, apparatus, computer equipment, medium, and product for determining quantum gate decoherence error. Background Technology

[0002] In the field of quantum computing, superconducting qubits, with their core advantage of precisely controlling their operating frequency through external electromagnetic fields, have become one of the main platforms for current quantum computing research. Their core advantage lies in the ability to precisely control the operating frequency of the qubit through external electromagnetic fields, thereby enabling flexible quantum gate operations in multi-qubit systems and effectively reducing crosstalk caused by frequency overlap. However, this tunability also makes the decoherence behavior of the qubit more complex; noise characteristics at different frequencies significantly affect the coherence time and quantum gate fidelity of the qubit. In superconducting quantum computing, qubit decoherence mainly stems from two mechanisms: relaxation: energy relaxation of the qubit leads to information loss, limited by dielectric losses, Josephson junction noise, and environmental coupling. dephase: the phase of the qubit is affected by low-frequency noise, thermal noise, and additional noise introduced by quantum gate operations, leading to loss of coherence. The decoherence characteristics of tunable frequency qubits are closely related to their operating frequency. For example, the low-frequency noise (1 / f) of a superconducting quantum bit is typically strong within a specific frequency range, while high-frequency environmental noise can lead to more severe relaxation at certain operating points. This means that decoherence fluctuates with frequency, causing quantum states to lose coherence and resulting in errors or biases in quantum computing. For instance, decoherence in quantum gate operations reduces fidelity, ultimately affecting the accuracy of computational results. This bias caused by decoherence can be considered quantum gate decoherence error. Therefore, quantum gate decoherence error at the test frequency is particularly important.

[0003] Currently, it is necessary to first determine the frequency of the qubit to be tested, then adjust the measurement and control parameters (such as amplitude and phase) at that qubit frequency, and finally test the quantum gate decoherence error at that qubit frequency.

[0004] However, adjusting the measurement and control parameters is time-consuming, and there is a problem of low efficiency in determining the quantum gate decoherence error. Summary of the Invention

[0005] Therefore, it is necessary to provide a method, apparatus, computer equipment, medium, and product for determining quantum gate decoherence error that can improve the determination efficiency of quantum gate decoherence error in response to the above-mentioned technical problems.

[0006] In a first aspect, this application provides a method for determining quantum gate decoherence error, including:

[0007] A first Z-pulse is applied to the quantum bit, and a first virtual Z-gate is applied to the quantum bit after the first Z-pulse to construct a first idle gate corresponding to a first preset frequency; the first Z-pulse is used to adjust the quantum bit from the idle frequency to the first preset frequency;

[0008] For each gate sequence, the quantum gates in the gate sequence are interleaved with the first idle gate to obtain the first target gate sequence. Based on each first target gate sequence, the first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the first idle gate is determined.

[0009] Based on the first parameter and the second parameter, the quantum gate decoherence error corresponding to the first preset frequency is determined; the second parameter is a second parameter related to the average error of quantum gate operation in a standard random benchmark test.

[0010] In one embodiment, based on each first target gate sequence, a first parameter related to the average error of quantum gate operations in the decorrelated random benchmark test corresponding to the first idle gate is determined, including:

[0011] For each first target gate sequence, after applying a reversal gate to the end of the first target gate sequence to reverse the first target gate sequence, the ground state probability corresponding to the first target gate sequence is obtained.

[0012] Based on the ground state probability corresponding to each first target gate sequence and the number of quantum gates in the first target gate sequence, the exponential decay curve of the ground state probability as a function of the number of gates is determined.

[0013] The first parameter is determined based on the exponential decay curve.

[0014] In one embodiment, determining the quantum gate decoherence error corresponding to a first preset frequency based on a first parameter and a second parameter includes:

[0015] Determine the first ratio between the first parameter and the second parameter;

[0016] Determine the first difference between the preset value and the first ratio, and determine the second difference between the dimension of the Hilbert space and the preset value;

[0017] Determine the product of the first difference and the second difference, and determine the second ratio of the product to the dimension;

[0018] The quantum gate decoherence error corresponding to the first preset frequency is determined based on the second ratio.

[0019] In one embodiment, determining the quantum gate decoherence error corresponding to the first preset frequency based on the second ratio includes:

[0020] The second ratio is determined to be the quantum gate decoherence error corresponding to the first preset frequency.

[0021] In one embodiment, the method further includes:

[0022] Given the quantum gate decoherence error corresponding to the first preset frequency, a second Z pulse is applied to the quantum bit, and a second virtual Z gate is applied to the quantum bit after the second Z pulse to construct a second idle gate corresponding to the second preset frequency; the second Z pulse is used to adjust the quantum bit from the idle frequency to the second preset frequency.

[0023] For each gate sequence, the quantum gates in the gate sequence are interleaved with the second idle gate to obtain the second target gate sequence. Based on each second target gate sequence, a new first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the second idle gate is determined.

[0024] Based on the new first and second parameters, the quantum gate decoherence error corresponding to the second preset frequency is determined.

[0025] In one embodiment, the target preset frequency includes a first preset frequency or a second preset frequency, and the method further includes:

[0026] Based on the target preset frequency and the preset correspondence, the target Z-pulse amplitude corresponding to the target preset frequency is determined; the preset correspondence includes the correspondence between the preset frequency and the Z-pulse amplitude; the target Z-pulse amplitude includes the first Z-pulse amplitude corresponding to the first preset frequency or the second Z-pulse amplitude corresponding to the second preset frequency;

[0027] The target Z-pulse is determined based on the target Z-pulse amplitude.

[0028] Secondly, this application also provides a quantum gate decoherence error determination device, comprising:

[0029] A construction module is used to apply a first Z pulse to the quantum bit and apply a first virtual Z gate to the quantum bit after the first Z pulse to construct a first idle gate corresponding to a first preset frequency; the first Z pulse is used to adjust the quantum bit from the idle frequency to the first preset frequency;

[0030] The first determining module is used to, for each gate sequence, interleave each quantum gate in the gate sequence with the first idle gate to obtain a first target gate sequence, and based on each first target gate sequence, determine a first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the first idle gate;

[0031] The second determining module is used to determine the quantum gate decoherence error corresponding to the first preset frequency based on the first parameter and the second parameter; the second parameter is a second parameter related to the average error of quantum gate operation in a standard random benchmark test.

[0032] Thirdly, this application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0033] A first Z-pulse is applied to the quantum bit, and a first virtual Z-gate is applied to the quantum bit after the first Z-pulse to construct a first idle gate corresponding to a first preset frequency; the first Z-pulse is used to adjust the quantum bit from the idle frequency to the first preset frequency;

[0034] For each gate sequence, the quantum gates in the gate sequence are interleaved with the first idle gate to obtain the first target gate sequence. Based on each first target gate sequence, the first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the first idle gate is determined.

[0035] Based on the first parameter and the second parameter, the quantum gate decoherence error corresponding to the first preset frequency is determined; the second parameter is a second parameter related to the average error of quantum gate operation in a standard random benchmark test.

[0036] Fourthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the following steps:

[0037] A first Z-pulse is applied to the quantum bit, and a first virtual Z-gate is applied to the quantum bit after the first Z-pulse to construct a first idle gate corresponding to a first preset frequency; the first Z-pulse is used to adjust the quantum bit from the idle frequency to the first preset frequency;

[0038] For each gate sequence, the quantum gates in the gate sequence are interleaved with the first idle gate to obtain the first target gate sequence. Based on each first target gate sequence, the first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the first idle gate is determined.

[0039] Based on the first parameter and the second parameter, the quantum gate decoherence error corresponding to the first preset frequency is determined; the second parameter is a second parameter related to the average error of quantum gate operation in a standard random benchmark test.

[0040] Fifthly, this application also provides a computer program product, including a computer program that, when executed by a processor, performs the following steps:

[0041] A first Z-pulse is applied to the quantum bit, and a first virtual Z-gate is applied to the quantum bit after the first Z-pulse to construct a first idle gate corresponding to a first preset frequency; the first Z-pulse is used to adjust the quantum bit from the idle frequency to the first preset frequency;

[0042] For each gate sequence, the quantum gates in the gate sequence are interleaved with the first idle gate to obtain the first target gate sequence. Based on each first target gate sequence, the first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the first idle gate is determined.

[0043] Based on the first parameter and the second parameter, the quantum gate decoherence error corresponding to the first preset frequency is determined; the second parameter is a second parameter related to the average error of quantum gate operation in a standard random benchmark test.

[0044] The aforementioned method, apparatus, computer equipment, medium, and product for determining quantum gate decoherence error apply a first Z-pulse to quantum bits, and then apply a first virtual Z-gate to the quantum bits after the first Z-pulse to construct a first idle gate corresponding to a first preset frequency. For each gate sequence, the quantum gates in the gate sequence are interleaved with the first idle gate to obtain a first target gate sequence. Based on each first target gate sequence, a first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the first idle gate is determined. Then, based on the first parameter and a second parameter related to the average error of quantum gate operation in the standard random benchmark test, the quantum gate decoherence error corresponding to the first preset frequency is determined. Since the quantum gate decoherence error corresponding to the first preset frequency can be determined without adjusting the measurement and control parameters, the time required to determine the quantum gate decoherence error is saved, thus improving the efficiency of quantum gate decoherence error determination. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a diagram illustrating the application environment of a quantum gate decoherence error determination method in one embodiment.

[0047] Figure 2 This is a flowchart illustrating a method for determining quantum gate decoherence error provided in an embodiment of this application;

[0048] Figure 3 This application provides a timing diagram for an interleaved random benchmark test and a standard random benchmark test.

[0049] Figure 4 This is a flowchart illustrating a method for determining a first parameter provided in an embodiment of this application;

[0050] Figure 5This is a flowchart illustrating another method for determining quantum gate decoherence error provided in an embodiment of this application;

[0051] Figure 6 This is a flowchart illustrating another method for determining quantum gate decoherence error provided in an embodiment of this application;

[0052] Figure 7 This is a flowchart illustrating a Z-pulse determination method provided in an embodiment of this application;

[0053] Figure 8 This is a schematic diagram of bit frequency modulation provided in an embodiment of this application;

[0054] Figure 9 This is a schematic diagram of the overall process of a quantum gate decoherence error determination method provided in an embodiment of this application;

[0055] Figure 10 This is a structural block diagram of a quantum gate decoherence error determination device in one embodiment. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0057] It should be noted that the terms "first," "second," etc., used in this application can be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from the second element. The terms "comprising" and "having," and any variations thereof, used in this application, are intended to cover non-exclusive inclusion. The term "multiple" used in this application refers to two or more. The term "and / or" used in this application refers to one of the embodiments, or any combination of multiple embodiments.

[0058] In one exemplary embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 1As shown, the computer device includes a processor, memory, input / output interface, communication interface, display unit, and input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The input / output interface is used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, Near Field Communication (NFC), or other technologies. When executed by the processor, the computer program implements a quantum gate decoherence error determination method. The display unit is used to form a visually visible image and can be a display screen, projection device, or virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the computer device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the casing of the computer device, or external keyboards, touchpads, or mice, etc.

[0059] Those skilled in the art will understand that Figure 1 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0060] In one exemplary embodiment, such as Figure 2 As shown, Figure 2 This is a flowchart illustrating a method for determining quantum gate decoherence error according to an embodiment of this application, applied to... Figure 1 The following steps, S201 to S203, are used as an example of computer equipment in the example:

[0061] S201, a first Z pulse is applied to the quantum bit, and a first virtual Z gate is applied to the quantum bit after the first Z pulse to construct a first idle gate corresponding to a first preset frequency; the first Z pulse is used to adjust the quantum bit from the idle frequency to the first preset frequency.

[0062] Among them, such as Figure 3 As shown, Figure 3This application provides a timing diagram for an interleaved random benchmark test and a standard random benchmark test. The first Z pulse is as follows: Figure 3 The line segment with arrows at both ends indicates a Z-pulse with amplitude Vz applied within a time period t. The first virtual Z-gate is... Figure 3 The one shown The first idle gate includes a first Z-pulse and a first virtual Z-gate. The first virtual Z-gate can be calculated based on a first preset frequency. The first virtual Z-gate is used to cancel the phase shift caused by applying the first Z-pulse, thereby constructing an ideal first idle gate without phase shift.

[0063] The amplitude of the first Z-pulse corresponding to the first preset frequency can be determined based on the first preset frequency and the corresponding relationship, and the first Z-pulse can be determined based on the amplitude of the first Z-pulse; the corresponding relationship includes the correspondence between the preset frequency and the amplitude of the Z-pulse.

[0064] S202, for each gate sequence, the quantum gates in the gate sequence are interleaved with the first idle gate to obtain the first target gate sequence, and based on each first target gate sequence, the first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the first idle gate is determined.

[0065] A gate sequence can include a Clifford gate sequence, and a gate sequence can include m Clifford gates. A Clifford gate uses... This means that the first target gate sequence is obtained by alternating the quantum gates in the gate sequence with the first free gate.

[0066] For example, when m=1, the first target gate sequence obtained by alternating the quantum gates in the gate sequence with the first free gate is: +First empty door.

[0067] When m=2, the first target gate sequence obtained by alternating the quantum gates in the gate sequence with the first free gate is as follows: +First Idle Gate+ +First empty door.

[0068] When m=3, the first target gate sequence obtained by alternating the quantum gates in the gate sequence with the first free gate is as follows: +First Idle Gate+ +First Idle Gate+ +First empty door.

[0069] For different m, Each sequence is randomly generated.

[0070] For each first target gate sequence, after applying an inversion gate at the end of the first target gate sequence to invert the first target gate sequence, the ground state probability corresponding to the first target gate sequence is obtained; based on the ground state probability corresponding to each first target gate sequence and the number of quantum gates in the first target gate sequence, the exponential decay curve of the ground state probability changing with the number of gates is determined; the first parameter is determined based on the exponential decay curve.

[0071] For example, where a reversing door is used This means, for example, when m=1, in +At the end of the first empty door, apply a reverse door, that is +First Idle Gate+ Then, the probability that the quantum state is in the ground state, also known as the ground state probability, is measured. This ground state probability is used as... +The ground state probability corresponding to the first free gate. When m=2, in +First Idle Gate+ +At the end of the first empty door, apply a reverse door, that is +First Idle Gate+ +First Idle Gate+ Then, the ground state probability is measured, and this ground state probability is used as... +First Idle Gate+ + The ground state probability corresponding to the first idle gate. When m=3. +First Idle Gate+ +First Idle Gate+ +At the end of the first empty door, apply a reverse door, that is +First Idle Gate+ +First Idle Gate+ +First Idle Gate+ Then, the ground state probability is measured, and this ground state probability is used as... +First Idle Gate+ +First Idle Gate+ + The ground state probability corresponding to the first free gate.

[0072] The exponential decay curve can be represented by the equation It means that, among them Let m represent the ground state probability, A and B represent the gate number, and A and B represent the ground state preparation and measurement errors, respectively. This can be based on... Determine the first parameter, for example, determine The first parameter, or determined. The product of the first parameter and a preset value is the first parameter.

[0073] S203, based on the first parameter and the second parameter, determine the quantum gate decoherence error corresponding to the first preset frequency; the second parameter is a second parameter related to the average error of quantum gate operation in a standard random benchmark test.

[0074] Reference Figure 3 Single-qubit standard random benchmark tests, such as Figure 3 As shown, it may include the following steps:

[0075] 1) Initialize the idle frequency qubits to the ground state.

[0076] 2) Apply a sequence of gates, including m Clifford gates, to the qubit. Assume that m = m1 in the first standard random benchmark test.

[0077] 3) Add a reversal gate at the end of the gate sequence to reverse the sequence. Turn the door around It acts on the qubit; it cancels out the synthesis operation of the entire gate sequence in step 2.

[0078] 4) Measure the probability that the qubit is in the ground state after being acted upon by the gate sequence and the inversion gate of the gate sequence. Figure 3 The last box on the right is a symbolic representation of a measurement operation, representing the measurement of a qubit to obtain the probability that the qubit is in its ground state.

[0079] 5) Perform steps 1-4 a total of K times and obtain K probabilities that the qubit remains in the ground state; for example, K=5, obtain 5 probabilities, calculate the average of the 5 probabilities, and denote the average probability as P(m1).

[0080] 6) Change m1 to m2 again and repeat steps 1-5. The average probability is denoted as P(m2). After the above steps 1-6, for example, a total of 100 probability averages are obtained from P(m1) to P(m100).

[0081] 7) Fit the curves based on P(m1) to P(m100) and a pre-established exponential decay curve; the exponential decay curve can be obtained using the equation... Indicated. Determined based on the exponential decay curve. Due to the average error of quantum gate operation for each Clifford gate . It is the dimension of the Hilbert space, therefore, from It can be seen from the formula It is a parameter related to the average error of quantum gate operations in standard random benchmark tests, namely the second parameter. This represents the number of qubits in a quantum system, as shown in this embodiment. It can be equal to 1.

[0082] In this embodiment, a first ratio of the first parameter to the second parameter can be determined; a first difference between a preset value and the first ratio can be determined, and a second difference between the dimension of the Hilbert space and the preset value can be determined; the product of the first difference and the second difference can be determined, and a second ratio between the product and the dimension can be determined; the second ratio can be determined as the quantum gate decoherence error corresponding to the first preset frequency, or the product of the second ratio and a preset coefficient can be determined as the quantum gate decoherence error corresponding to the first preset frequency.

[0083] In this embodiment, a first Z-pulse is applied to the quantum bits, and a first virtual Z-gate is applied to the quantum bits after the first Z-pulse to construct a first idle gate corresponding to a first preset frequency. For each gate sequence, the quantum gates in the gate sequence are interleaved with the first idle gate to obtain a first target gate sequence. Based on each first target gate sequence, a first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the first idle gate is determined. Then, based on the first parameter and a second parameter related to the average error of quantum gate operation in the standard random benchmark test, the quantum gate decoherence error corresponding to the first preset frequency is determined. Since the quantum gate decoherence error corresponding to the first preset frequency can be determined without adjusting the measurement and control parameters, the time required to determine the quantum gate decoherence error is saved, and the determination efficiency of the quantum gate decoherence error is improved.

[0084] In one exemplary embodiment, such as Figure 4 As shown, Figure 4 This is a flowchart illustrating a method for determining a first parameter provided in an embodiment of this application. The step S202 above, "determining the first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the first idle gate based on each first target gate sequence", may include steps S401 to S403.

[0085] S401, for each first target gate sequence, after applying an inversion gate that inverts the first target gate sequence at the end of the first target gate sequence, obtain the ground state probability corresponding to the first target gate sequence.

[0086] S402, based on the ground state probability corresponding to each first target gate sequence and the number of quantum gates in the first target gate sequence, determine the exponential decay curve of the ground state probability as a function of the number of gates.

[0087] S403, the first parameter is determined based on the exponential decay curve.

[0088] In this embodiment, by applying an inversion gate to the end of the first target gate sequence to invert the first target gate sequence, the ground state probability corresponding to the first target gate sequence is obtained. Based on the ground state probability corresponding to each first target gate sequence and the number of quantum gates in the first target gate sequence, the exponential decay curve of the ground state probability changing with the number of gates is determined. Based on the exponential decay curve, the first parameter is determined, thus providing a basis for subsequently determining the quantum gate decoherence error corresponding to the first preset frequency.

[0089] In one exemplary embodiment, such as Figure 5 As shown, Figure 5 This is a flowchart illustrating another method for determining quantum gate decoherence error provided in this application embodiment. The above-mentioned S203 may include S501 to S504.

[0090] S501, determine the first ratio of the first parameter to the second parameter.

[0091] S502, determine the first difference between the preset value and the first ratio, and determine the second difference between the dimension of the Hilbert space and the preset value.

[0092] S503, determine the product of the first difference and the second difference, and determine the second ratio of the product to the dimension.

[0093] S504, determine the quantum gate decoherence error corresponding to the first preset frequency based on the second ratio.

[0094] The quantum gate decoherence error corresponding to a preset frequency can be determined based on the following formula:

[0095]

[0096] in, This represents the quantum gate decoherence error. This represents the first parameter corresponding to the preset frequency. Referring to the example above, when the preset frequency is the first preset frequency... It is equal to the first parameter determined in S202 above. The preset value in the above quantum gate decoherence error formula is equal to 1.

[0097] In this embodiment, by determining a first ratio between the first parameter and the second parameter, a first difference between a preset value and the first ratio, and a second difference between the dimension of the Hilbert space and the preset value, the product of the first difference and the second difference is determined, and a second ratio between the product and the dimension is determined. Then, based on the second ratio, the quantum gate decoherence error corresponding to the first preset frequency is determined. Since no adjustment of the measurement and control parameters is required, the probability of low accuracy of the determined decoherence error due to measurement and control parameter adjustment errors can be reduced, thereby improving the accuracy of the obtained decoherence error.

[0098] In an exemplary embodiment, the above-described S504 can be implemented as follows:

[0099] The second ratio is determined to be the quantum gate decoherence error corresponding to the first preset frequency.

[0100] In this embodiment, the second ratio is directly determined to be the quantum gate decoherence error corresponding to the first preset frequency. The determination method is relatively simple, thereby improving the efficiency of obtaining the quantum gate decoherence error.

[0101] In one exemplary embodiment, such as Figure 6 As shown, Figure 6 This is a flowchart illustrating another method for determining quantum gate decoherence error provided in this application embodiment, which includes the following steps S601-S603.

[0102] S601, when the decoherence error of the quantum gate corresponding to the first preset frequency is determined, a second Z pulse is applied to the quantum bit, and a second virtual Z gate is applied to the quantum bit after the second Z pulse to construct a second idle gate corresponding to the second preset frequency; the second Z pulse is used to adjust the quantum bit from the idle frequency to the second preset frequency.

[0103] like Figure 3 As shown, after the first Z-pulse application ends, the qubit returns from the first preset frequency to the idle frequency. Then, after determining the quantum gate decoherence error corresponding to the first preset frequency, a second Z-pulse can be applied to the qubit, and a second virtual Z-gate can be applied to the qubit after the second Z-pulse to construct a second idle gate corresponding to the second preset frequency. The second virtual Z-gate can be calculated based on the second preset frequency.

[0104] Understandably, when the second Z-pulse ends, the qubit returns from the second preset frequency to the idle frequency. In this case, a third Z-pulse can be applied to the qubit, and a third virtual Z-gate can be applied after the third Z-pulse to construct a second idle gate corresponding to the third preset frequency. The second virtual Z-gate can be calculated based on the second preset frequency, and the third Z-pulse is used to adjust the qubit from the idle frequency to the third preset frequency.

[0105] Similarly, if the qubit returns from its current preset frequency to its idle frequency after the current Z-pulse application ends, a next Z-pulse can be applied to the qubit, followed by a next virtual Z-gate to construct a next idle gate corresponding to the next preset frequency. The next virtual Z-gate can be calculated based on the next preset frequency, and the next Z-pulse is used to adjust the qubit from its idle frequency to the next preset frequency. For example, the current Z-pulse is the first Z-pulse, the next Z-pulse is the second Z-pulse, the next preset frequency is the second preset frequency, and the next idle gate includes both the next Z-pulse and the next virtual Z-gate.

[0106] S602, for each gate sequence, the quantum gates in the gate sequence are interleaved with the second idle gate to obtain the second target gate sequence, and based on each second target gate sequence, a new first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the second idle gate is determined.

[0107] The method for determining the new first parameter in this step is similar to the method for determining the first parameter in S202 above, and will not be repeated here.

[0108] S603, based on the new first and second parameters, determines the quantum gate decoherence error corresponding to the second preset frequency.

[0109] In this step, the quantum gate decoherence error corresponding to the second preset frequency is determined based on the new first and second parameters. This method is similar to the method for determining the quantum gate decoherence error corresponding to the first preset frequency in S203 above, and will not be repeated here.

[0110] It is understandable that if it is necessary to determine the quantum gate decoherence error corresponding to other preset frequencies, steps similar to S601-S603 above can be used to determine the quantum gate decoherence error corresponding to the other preset frequencies until the quantum gate decoherence error corresponding to each preset frequency that needs to be determined is determined.

[0111] In traditional techniques, if it is necessary to test the quantum gate decoherence error at multiple preset frequencies (i.e., multiple qubit frequencies), it is necessary to first determine the frequency of the qubit to be tested, then adjust the measurement and control parameters (such as frequency, amplitude, phase, etc.) at that qubit frequency, and finally test the quantum gate decoherence error at that qubit frequency. Then, the qubit frequency is changed, the measurement and control parameters are readjusted, and the above quantum gate decoherence error test is repeated. Therefore, the test procedure for measuring the quantum gate decoherence error at different qubit frequencies is quite cumbersome.

[0112] In this embodiment, no adjustment of measurement and control parameters is required during the testing of quantum gate decoherence errors at various preset frequencies, thereby simplifying the testing process and improving the efficiency of testing quantum gate decoherence errors at multiple preset frequencies. By dynamically modulating the frequency, a calibration method for quantum gate decoherence errors at different preset frequencies is determined, enabling the test to cover different pulse lengths and bit frequencies, providing a more comprehensive assessment of quantum gate decoherence errors.

[0113] In this embodiment, after determining the quantum gate decoherence error corresponding to the first preset frequency, a second Z-pulse is applied to the quantum bits, and a second virtual Z-gate is applied to the quantum bits after the second Z-pulse to construct a second idle gate corresponding to the second preset frequency. For each gate sequence, the quantum gates in the gate sequence are interleaved with the second idle gate to obtain a second target gate sequence. Based on each second target gate sequence, a new first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the second idle gate is determined. Then, based on the new first parameter and the second parameter, the quantum gate decoherence error corresponding to the second preset frequency is determined. Since there is no need to adjust the measurement and control parameters during the testing of quantum gate decoherence errors at multiple preset frequencies, the testing process is simplified and the efficiency of testing quantum gate decoherence errors at multiple preset frequencies is improved.

[0114] In one exemplary embodiment, such as Figure 7 As shown, Figure 7 This is a flowchart illustrating a Z-pulse determination method provided in an embodiment of this application. The method includes the following steps S701-S702.

[0115] S701, based on the target preset frequency and the preset correspondence, determines the target Z pulse amplitude corresponding to the target preset frequency.

[0116] The preset correspondence includes the correspondence between preset frequencies and Z-pulse amplitudes; the target Z-pulse amplitude includes either a first Z-pulse amplitude corresponding to a first preset frequency or a second Z-pulse amplitude corresponding to a second preset frequency. The first Z-pulse can be determined based on the first Z-pulse amplitude, and the second Z-pulse can be determined based on the second Z-pulse amplitude. The lengths of the first and second Z-pulses can be the same or different.

[0117] It is understandable that the first Z pulse mentioned above can be understood as the currently applied Z pulse, and the second Z pulse is the next Z pulse that follows the currently applied Z pulse.

[0118] like Figure 8 As shown, Figure 8 This is a schematic diagram of bit frequency modulation provided in an embodiment of this application. Figure 8The horizontal axis represents the Z-pulse amplitude, and the vertical axis represents the bit frequency. The blue curve shows the correspondence between the preset frequency and the Z-pulse amplitude. Based on this blue curve, the Z-pulse amplitude corresponding to the preset frequency can be determined. Black lines with higher frequencies and right-pointing arrows indicate that after applying a Z-pulse, the bit frequency modulates from the idle frequency (approximately 5.2 GHz) to the preset frequency (approximately 4.4 GHz). After the Z-pulse ends, black lines with left-pointing arrows indicate that the bit frequency returns from the preset frequency of 4.4 GHz to the idle frequency of 5.2 GHz. ( This indicates the Z-pulse amplitude corresponding to the idle frequency. ( ) represents the Z-pulse amplitude corresponding to the preset frequency.

[0119] S702, determine the target Z pulse based on the target Z pulse amplitude.

[0120] One of the core advantages of superconducting qubits lies in their ability to control their operating frequency via an external electromagnetic field—specifically, Z-pulse control of the electromagnetic field, which in turn controls the operating frequency. This frequency tunability allows for flexible adaptation to quantum gate operation requirements and effectively avoids crosstalk caused by frequency overlap in multi-qubit systems. However, the noise sensitivity of this system exhibits a significant spectral dependence; qubits with different frequency parameters are affected differently by decoherent noise. In superconducting qubit systems, we achieve qubit frequency control through Z-control pulses. Dynamic modulation, Reflects the amplitude of the Z-pulse Bit frequency, also known as preset frequency The correspondence between them.

[0121] During the Z-pulse of duration t, the system will accumulate a dynamic phase due to the time-varying characteristics of the Hamiltonian. Therefore, in order to construct a phase-shift-free idle gate, we introduce a virtual Z-gate technique, which applies an equivalent virtual phase rotation at the software level by adjusting the quantum state Bloch sphere reference coordinate system in real time. In other words, the virtual Z-gate corresponding to the preset frequency is used to cancel the phase shift of the qubit's dynamic phase caused by applying the Z-pulse corresponding to the preset frequency, relative to the phase shift when the Z-pulse is not applied.

[0122] For example, after the first Z pulse lasts for a duration of t, the dynamic phase of the qubit caused by the first Z pulse is: The dynamic phase without the first Z-pulse is 0, meaning the phase shift caused by applying the first Z-pulse is... Then, by introducing a first virtual Z-gate, an equivalent virtual phase rotation is applied at the software level. This can thus offset the phase shift caused by applying the first Z pulse. This allows for the construction of an ideal free gate without phase shift. For example, the first free gate or the second free gate mentioned above.

[0123] Programmable free gate The system constructs a virtual Z-gate. By actively applying Z-pulses, dynamic modulation of the bit frequency is achieved. For example, applying a first Z-pulse modulates the frequency from the idle frequency to a first preset frequency; applying a second Z-pulse modulates the frequency from the idle frequency to a second preset frequency. This dynamic modulation of the bit frequency allows for the measurement of quantum gate decoherence errors at different bit frequencies and time scales. Simultaneously, combined with virtual Z-gate phase compensation technology, the idle gate can effectively counteract dynamic phase accumulation, achieving an ideal idle gate without phase shift.

[0124] In this embodiment, the target Z-pulse amplitude corresponding to the target preset frequency is determined based on the target preset frequency and the preset correspondence, and the target Z-pulse is determined based on the target Z-pulse amplitude, thereby laying the foundation for constructing an idle gate based on the target Z-pulse.

[0125] In one embodiment, the quantum gate parameters can be optimized based on the quantum gate decoherence error at different preset frequencies. For example, the preset frequency, amplitude, and length of the Z-pulse corresponding to the minimum quantum gate decoherence error can be used as the optimized quantum gate parameters. When the preset frequency corresponding to the minimum quantum gate decoherence error is found, it means that at that preset frequency, the qubit can maintain its quantum state for a relatively long time, reducing the loss of quantum information, making the quantum computing process more stable, ensuring that the computing task can be completed smoothly, reducing the probability of errors in the computing results, and improving the accuracy of quantum gate operations.

[0126] In one embodiment, such as Figure 9 As shown, Figure 9 This is a schematic diagram of the overall process of a quantum gate decoherence error determination method provided in an embodiment of this application. The method includes the following steps:

[0127] S901 determines a second parameter related to the average error of quantum gate operations in standard random benchmark tests.

[0128] S902, based on the first preset frequency and the preset correspondence, determine the amplitude of the first Z pulse corresponding to the first preset frequency, and determine the first Z pulse according to the amplitude of the first Z pulse.

[0129] S903, a first Z pulse is applied to the vector sub-bits, and a first virtual Z gate is applied to the vector sub-bits after the first Z pulse to construct a first idle gate corresponding to a first preset frequency.

[0130] S904, for each gate sequence, the quantum gates in the gate sequence are interleaved with the first idle gate to obtain the first target gate sequence, and based on each first target gate sequence, the first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the first idle gate is determined.

[0131] S905, based on the first parameter and the second parameter, determine the quantum gate decoherence error corresponding to the first preset frequency.

[0132] S906, after determining the quantum gate decoherence error corresponding to the first preset frequency, a second Z pulse is applied to the quantum bits, and a second virtual Z gate is applied to the quantum bits after the second Z pulse to construct a second idle gate corresponding to the second preset frequency.

[0133] S907, for each gate sequence, the quantum gates in the gate sequence are interleaved with the second idle gate to obtain the second target gate sequence, and based on each second target gate sequence, a new first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the second idle gate is determined.

[0134] S908, based on the new first and second parameters, determines the quantum gate decoherence error corresponding to the second preset frequency.

[0135] It should be understood that although the steps in the flowcharts of the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps. It is understood that the steps in different embodiments can be freely combined as needed, and all non-contradictory solutions formed by such combinations are within the scope of protection of this application.

[0136] Based on the same inventive concept, this application also provides a quantum gate decoherence error determination device for implementing the quantum gate decoherence error determination method described above. The solution provided by this device is similar to the solution described in the above method; therefore, the specific limitations of one or more quantum gate decoherence error determination device embodiments provided below can be found in the limitations of the quantum gate decoherence error determination method described above, and will not be repeated here.

[0137] In one exemplary embodiment, such as Figure 10 As shown, Figure 10 This is a schematic diagram of a quantum gate decoherence error determination device provided in an embodiment of this application. The quantum gate decoherence error determination device 1000 includes:

[0138] The construction module 1001 is used to apply a first Z pulse to the quantum bit and apply a first virtual Z gate to the quantum bit after the first Z pulse to construct a first idle gate corresponding to a first preset frequency; the first Z pulse is used to adjust the quantum bit from the idle frequency to the first preset frequency.

[0139] The first determining module 1002 is used to, for each gate sequence, interleave each quantum gate in the gate sequence with the first idle gate to obtain a first target gate sequence, and based on each first target gate sequence, determine a first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the first idle gate;

[0140] The second determining module 1003 is used to determine the quantum gate decoherence error corresponding to the first preset frequency based on the first parameter and the second parameter; the second parameter is a second parameter related to the average error of quantum gate operation in a standard random benchmark test.

[0141] In one embodiment, the first determining module 1002 is specifically used to, for each first target gate sequence, apply an inversion gate to the end of the first target gate sequence to invert the first target gate sequence, obtain the ground state probability corresponding to the first target gate sequence; determine the exponential decay curve of the ground state probability changing with the number of gates based on the ground state probability corresponding to each first target gate sequence and the number of quantum gates in the first target gate sequence; and determine the first parameter based on the exponential decay curve.

[0142] In one embodiment, the second determining module 1003 includes:

[0143] The first determining unit is used to determine the first ratio between the first parameter and the second parameter;

[0144] The second determining unit is used to determine the first difference between the preset value and the first ratio, and to determine the second difference between the dimension of the Hilbert space and the preset value.

[0145] The third determining unit is used to determine the product of the first difference and the second difference, and to determine the second ratio of the product to the dimension;

[0146] The fourth determining unit is used to determine the quantum gate decoherence error corresponding to the first preset frequency based on the second ratio.

[0147] In one embodiment, the fourth determining unit is specifically used to determine the quantum gate decoherence error corresponding to the second ratio as the first preset frequency.

[0148] In one embodiment, the construction module 1001 is further configured to apply a second Z pulse to the quantum bit when the quantum gate decoherence error corresponding to the first preset frequency is determined, and apply a second virtual Z gate to the quantum bit after the second Z pulse to construct a second idle gate corresponding to the second preset frequency; the second Z pulse is used to adjust the quantum bit from the idle frequency to the second preset frequency.

[0149] The first determining module 1002 is further configured to, for each gate sequence, interleave each quantum gate in the gate sequence with the second idle gate to obtain a second target gate sequence, and based on each second target gate sequence, determine a new first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the second idle gate;

[0150] The second determining module 1003 is also used to determine the quantum gate decoherence error corresponding to the second preset frequency based on the new first parameter and the second parameter.

[0151] In one embodiment, the target preset frequency includes a first preset frequency or a second preset frequency, and the quantum gate decoherence error determination device 1000 may further include:

[0152] The third determining module is used to determine the target Z-pulse amplitude corresponding to the target preset frequency based on the target preset frequency and the preset correspondence relationship; the preset correspondence relationship includes the correspondence relationship between the preset frequency and the Z-pulse amplitude; the target Z-pulse amplitude includes the first Z-pulse amplitude corresponding to the first preset frequency or the second Z-pulse amplitude corresponding to the second preset frequency;

[0153] The fourth determination module is used to determine the target Z-pulse based on the target Z-pulse amplitude.

[0154] Each module in the aforementioned quantum gate decoherence error determination device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in hardware within or independently of the processor in a computer device, or stored in software within the memory of the computer device, so that the processor can call and execute the operations corresponding to each module.

[0155] In one exemplary embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps of any of the above method embodiments. The technical principles and effects are similar, and will not be repeated here.

[0156] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, it implements the steps of any of the above method embodiments. The technical principles and effects are similar and will not be repeated here.

[0157] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps of any of the above method embodiments. The technical principles and effects are similar and will not be repeated here.

[0158] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0159] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0160] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for determining quantum gate decoherence error, characterized in that, The method includes: A first Z-pulse is applied to the quantum bit, and a first virtual Z-gate is applied to the quantum bit after the first Z-pulse to construct a first idle gate corresponding to a first preset frequency; the first Z-pulse is used to adjust the quantum bit from the idle frequency to the first preset frequency; For each gate sequence, each quantum gate in the gate sequence is interleaved with the first idle gate to obtain a first target gate sequence, and based on each first target gate sequence, a first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the first idle gate is determined; Based on the first parameter and the second parameter, the quantum gate decoherence error corresponding to the first preset frequency is determined; the second parameter is a second parameter related to the average error of quantum gate operation in a standard random benchmark test.

2. The method according to claim 1, characterized in that, The step of determining a first parameter related to the average error of quantum gate operations in the decorrelated random benchmark test corresponding to each of the first target gate sequences includes: For each of the first target gate sequences, after applying a reversal gate to the end of the first target gate sequence to reverse the first target gate sequence, the ground state probability corresponding to the first target gate sequence is obtained. Based on the ground state probability corresponding to each of the first target gate sequences and the number of quantum gates in the first target gate sequence, an exponential decay curve of the ground state probability as a function of the number of gates is determined. The first parameter is determined based on the exponential decay curve.

3. The method according to claim 1 or 2, characterized in that, The step of determining the quantum gate decoherence error corresponding to the first preset frequency based on the first parameter and the second parameter includes: Determine a first ratio between the first parameter and the second parameter; Determine a first difference between a preset value and the first ratio, and determine a second difference between the dimension of the Hilbert space and the preset value; Determine the product of the first difference and the second difference, and determine a second ratio of the product to the dimension; The quantum gate decoherence error corresponding to the first preset frequency is determined based on the second ratio.

4. The method according to claim 3, characterized in that, The step of determining the quantum gate decoherence error corresponding to the first preset frequency based on the second ratio includes: The second ratio is determined to be the quantum gate decoherence error corresponding to the first preset frequency.

5. The method according to claim 1 or 2, characterized in that, The method further includes: If the decoherence error of the quantum gate corresponding to the first preset frequency is determined, a second Z pulse is applied to the quantum bit, and a second virtual Z gate is applied to the quantum bit after the second Z pulse to construct a second idle gate corresponding to the second preset frequency; the second Z pulse is used to adjust the quantum bit from the idle frequency to the second preset frequency; For each gate sequence, each quantum gate in the gate sequence is interleaved with the second idle gate to obtain a second target gate sequence, and based on each second target gate sequence, a new first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the second idle gate is determined; Based on the new first parameter and the second parameter, the quantum gate decoherence error corresponding to the second preset frequency is determined.

6. The method according to claim 5, characterized in that, The target preset frequency includes either the first preset frequency or the second preset frequency, and the method further includes: Based on a target preset frequency and a preset correspondence, a target Z-pulse amplitude corresponding to the target preset frequency is determined; the preset correspondence includes the correspondence between the preset frequency and the Z-pulse amplitude; the target Z-pulse amplitude includes the first Z-pulse amplitude corresponding to the first preset frequency or the second Z-pulse amplitude corresponding to the second preset frequency. The target Z-pulse is determined based on the target Z-pulse amplitude.

7. A device for determining quantum gate decoherence error, characterized in that, The device includes: A construction module is used to apply a first Z pulse to the quantum bit and apply a first virtual Z gate to the quantum bit after the first Z pulse to construct a first idle gate corresponding to a first preset frequency; the first Z pulse is used to adjust the quantum bit from the idle frequency to the first preset frequency; The first determining module is used to, for each gate sequence, interleave each quantum gate in the gate sequence with the first idle gate to obtain a first target gate sequence, and based on each first target gate sequence, determine a first parameter related to the average error of quantum gate operation in the interleaved random benchmark test corresponding to the first idle gate; The second determining module is used to determine the quantum gate decoherence error corresponding to the first preset frequency based on the first parameter and the second parameter; the second parameter is a second parameter related to the average error of quantum gate operation in a standard random benchmark test.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

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