Method for generating single flux quantum sequence and method for generating single quantum bit gate

Abstract

The present invention provides a method for generating a single flux quantum sequence and a method for generating a single quantum bit gate, which can be applied to the field of quantum computing technology. The method for generating a single flux quantum sequence comprises: generating m discrete sequences according to input waveform parameters in response to a sequence generation instruction; determining n target pulse grid points and a pulse time corresponding to each target pulse grid point according to waveform integral values ​​of the m waveform points; in the case where the preset coding scheme is an envelope integral pulse coding scheme, for each target pulse grid point, generating a pulse polarity value corresponding to the target pulse grid point according to the pulse time corresponding to the target pulse grid point and a pulse polarity judgment function; determining a first pulse code corresponding to the pulse polarity value according to the pulse polarity value and multiple polarity value ranges; and generating a first single flux quantum sequence according to n first pulse codes corresponding to the n target pulse grid points.

Description

Technical Field

[0001] The present invention relates to the technical field of quantum computing technology, and more specifically, to a method for generating a single magnetic flux quantum sequence and a method for generating a single quantum bit gate. Background Art

[0002] Single Flux Quantum (SFQ) is a superconducting digital logic technology that uses the smallest magnetic flux unit in superconducting materials to control and transmit information. Its main advantages are high speed, low power consumption and high sensitivity. In addition, SFQ technology has good tolerance to changes in manufacturing. With the rapid development of quantum computing technology, SFQ technology can play an important role in the fields of superconducting electronics and superconducting integrated circuit technology.

[0003] In the process of realizing the concept of the present invention, it is found that the generation efficiency of the single flux quantum sequence in the related art is low and the computing resources are large. Summary of the invention

[0004] In view of this, the present invention provides a method for generating a single flux quantum sequence and a single quantum bit gate.

[0005] One aspect of the present invention provides a method for generating a single magnetic flux quantum sequence, comprising: in response to a sequence generation instruction, generating m discrete sequences according to input waveform parameters, wherein each discrete sequence includes a waveform point, a waveform integral value, and a waveform time; determining n target pulse grid points and a pulse time corresponding to each target pulse grid point according to the waveform integral values ​​of the m waveform points; when the preset coding scheme is an envelope integral pulse coding scheme, for each target pulse grid point, generating a pulse polarity value corresponding to the target pulse grid point according to the pulse time and a pulse polarity judgment function corresponding to the target pulse grid point; determining a first pulse code corresponding to the pulse polarity value according to the pulse polarity value and multiple polarity value ranges; generating a first single magnetic flux quantum sequence according to the n first pulse codes corresponding to the n target pulse grid points, wherein m and n are both integers greater than or equal to 1.

[0006] According to an embodiment of the present invention, m discrete sequences are generated according to input waveform parameters, including: generating a guiding waveform according to the waveform parameters, wherein the waveform parameters include waveform frequency and / or waveform amplitude, and the guiding waveform includes an envelope function; performing time integration processing on the envelope function to obtain m discrete sequences.

[0007] According to an embodiment of the present invention, n target pulse grid points and a pulse time corresponding to each target pulse grid point are determined based on waveform integral values ​​of m waveform points, including: for the ith waveform point, a cumulative integral value of the ith waveform point is generated based on the waveform integral values ​​of the previous i waveform points; when the waveform time of the ith waveform point satisfies a preset time condition, the ith waveform point is determined as an initial pulse grid point; when the cumulative integral value of the initial pulse grid point satisfies a preset integral variable, the initial pulse grid point is determined as a target pulse grid point, the waveform time corresponding to the initial pulse grid point is determined as the pulse time, and a new cumulative integral value corresponding to the ith waveform point is generated based on the cumulative integral value of the initial pulse grid point and the preset integral variable.

[0008] According to an embodiment of the present invention, the cumulative integral value of the i-th waveform point is generated based on the waveform integral values ​​of the first i waveform points, including: when i is equal to 1, determining the waveform integral value of the i-th waveform point as the cumulative integral value of the i-th waveform point; when i is greater than 1, generating the cumulative integral value of the i-th waveform point based on the waveform integral value of the i-th waveform point and the target cumulative integral value of the i-1-th waveform point, wherein the target cumulative integral value includes the cumulative integral value of the i-1-th waveform point or a new cumulative integral value, and wherein i is an integer greater than 1.

[0009] According to an embodiment of the present invention, the plurality of polarity value ranges include a first value range, a second value range, and a third value range.

[0010] According to an embodiment of the present invention, a first pulse code corresponding to a pulse polarity value is determined based on a pulse polarity value and a plurality of polarity value ranges, including: generating a first pulse sub-code when the pulse polarity value satisfies a first value range; generating a second pulse sub-code when the pulse polarity value satisfies a second value range; generating a third pulse sub-code when the pulse polarity value satisfies a third value range, wherein the first pulse code includes a first pulse sub-code, a second pulse sub-code or a third pulse sub-code.

[0011] According to an embodiment of the present invention, the above-mentioned method for generating a single flux quantum sequence also includes: when the preset coding scheme is a mixing-based pulse coding scheme, for each target pulse grid point, according to the pulse time and pulse polarity guidance function corresponding to the target pulse grid point, a pulse guidance value corresponding to the target pulse grid point is generated; according to the pulse guidance value and multiple guidance value ranges, a second pulse code corresponding to the pulse guidance value is determined; according to the n second pulse codes corresponding to the n target pulse grid points, a second single flux quantum sequence is generated.

[0012] According to an embodiment of the present invention, the plurality of guide numerical ranges include a fourth numerical range, a fifth numerical range, and a sixth numerical range.

[0013] According to an embodiment of the present invention, a second pulse code corresponding to the pulse guide value is determined based on a pulse guide value and multiple guide value ranges, including: generating a fourth pulse sub-code when the pulse guide value satisfies a fourth value range; generating a fifth pulse sub-code when the pulse guide value satisfies a fifth value range; generating a sixth pulse sub-code when the pulse guide value satisfies a sixth value range, wherein the second pulse code includes a fourth pulse sub-code, a fifth pulse sub-code or a sixth pulse sub-code.

[0014] According to an embodiment of the present invention, the pulse polarity judgment function is shown in formula (1), and the pulse polarity guidance function is shown in formula (2):

[0015] (1);

[0016] (2);

[0017] in, is the pulse polarity value, f is the frequency of the superconducting bit f01 energy level, is the first initial phase, that is, the initial phase at time zero, is the second initial phase, is the third initial phase, is the preset parameter, is a parameter introduced to control the z error, t is the pulse time corresponding to the target pulse grid point, is the first frequency, is the second frequency, the first frequency and the second frequency both belong to the bit 01 and 12 energy levels, is the gate duration of a single-qubit gate.

[0018] According to an embodiment of the present invention, the above-mentioned method for generating a single flux quantum sequence also includes: adjusting the first initial phase or the second initial phase to continuously control the phase of the single quantum bit gate; and / or adjusting the preset parameters and the third initial phase to control the target state leakage during the gate action of the single quantum bit gate; and / or adjusting the first frequency to control the Z error during the gate action of the single quantum bit gate.

[0019] Another aspect of the present invention provides a method for generating a single-qubit gate, comprising: obtaining a single-flux quantum sequence; generating a control square wave sequence using a digital voltage source based on the single-flux quantum sequence; processing the control square wave sequence using a single-flux pulse generation circuit to generate a single-flux pulse signal; applying the single-flux pulse signal to the qubit to drive the target energy level inversion of the qubit and calculating the fidelity of the qubit; iteratively optimizing the waveform parameters of the single-flux pulse signal according to the fidelity to apply the optimized single-flux pulse signal to the qubit, thereby generating a single-qubit gate.

[0020] Another aspect of the present invention provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the above method.

[0021] Another aspect of the present invention provides a computer-readable storage medium storing computer-executable instructions, which are used to implement the above method when executed.

[0022] Another aspect of the present invention provides a computer program product, the computer program product comprising computer executable instructions, and the instructions are used to implement the above method when being executed.

[0023] According to the method for generating a single flux quantum sequence and a method for generating a single quantum bit gate provided by the present invention, n target pulse grid points are determined according to the waveform integral values ​​of m waveform points, and a pulse polarity value corresponding to each target pulse grid point is generated according to the pulse time and pulse polarity judgment function corresponding to the target pulse grid point, the pulse polarity value corresponding to each target pulse grid point is compared with a plurality of polarity value ranges, a first pulse code corresponding to the pulse polarity value is determined, and a first single flux quantum sequence is generated according to the n first pulse codes corresponding to the n target pulse grid points, thereby simplifying the method for generating a single flux quantum sequence, improving the generation efficiency of the single flux quantum sequence, and saving computing resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings.

[0025] Figure 1 A diagram showing an application scenario of a method for generating a single magnetic flux quantum sequence according to an embodiment of the present invention is shown.

[0026] Figure 2 A flow chart of a method for generating a single magnetic flux quantum sequence according to an embodiment of the present invention is shown.

[0027] Figure 3A flow chart of a method for generating a single quantum bit gate according to an embodiment of the present invention is shown.

[0028] Figure 4 A schematic diagram of a single magnetic flux quantum sequence generated by an envelope-integrated pulse coding scheme according to an embodiment of the present invention is shown.

[0029] Figure 5 A schematic diagram of a single magnetic flux quantum sequence generated by a filtered envelope-integrated pulse coding scheme according to an embodiment of the present invention is shown.

[0030] Figure 6 A schematic diagram showing the fidelity of adjusting the phase of a single-qubit gate using an envelope-integrated pulse coding scheme according to an embodiment of the present invention is shown.

[0031] Figure 7 A schematic diagram of a single magnetic flux quantum sequence generated by a frequency mixing-based pulse coding scheme according to an embodiment of the present invention is shown.

[0032] Figure 8 A schematic diagram of a single magnetic flux quantum sequence generated by a filtered mixing-based pulse coding scheme according to an embodiment of the present invention is shown.

[0033] Fig. 9 A schematic diagram of a two-qubit circuit according to an embodiment of the present invention is shown.

[0034] Fig.10 A block diagram of an electronic device suitable for implementing a method for generating a single magnetic flux quantum sequence according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0035] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0036] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0037] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0038] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0039] In the embodiments of the present invention, the collection, updating, analysis, processing, use, transmission, provision, disclosure, storage and other aspects of the data involved (for example, including but not limited to user personal information) are in compliance with the provisions of relevant laws and regulations, are used for legitimate purposes, and do not violate public order and good morals. In particular, necessary measures are taken for user personal information to prevent illegal access to user personal information data and maintain the security of user personal information and network security.

[0040] In the process of implementing the present invention, it is found that in the related art, a resonantly driven SFQ pulse is applied to a single bit, that is, the period of the applied SFQ pulse is equal to the rotation period of the superconducting bit f01. However, since the interval between pulses is an analog quantity, when the bit is actually used, the frequency of the bit is difficult to be fixed. If a resonant drive is used, it means that the SFQ pulse interval needs to change continuously with the bit frequency, which poses a great challenge to the design of SFQ logic and may be difficult to achieve experimentally. In addition, there is also a method of optimizing the bipolar (including three logical states of positive, negative pulses and 0 pulses) SFQ pulse sequence by using a genetic algorithm, and a method of selecting an initial sequence with lower state leakage is proposed, but more computing resources are required during calculation, and it is difficult to consider the case with filtering during optimization. In fact, it is necessary to filter out frequency components exceeding 8G, otherwise the energy may break up the Cooper pairs and cause additional errors. Therefore, the pulse sequence encoding scheme in the related art has problems such as large consumption of computing resources and inability to implement digital logic.

[0041] In view of this, an embodiment of the present invention provides a method for generating a single flux quantum sequence, comprising: generating m discrete sequences according to input waveform parameters in response to a sequence generation instruction, wherein each discrete sequence includes a waveform point, a waveform integral value, and a waveform time; determining n target pulse grid points and a pulse time corresponding to each target pulse grid point according to the waveform integral values ​​of the m waveform points; when the preset coding scheme is an envelope integral pulse coding scheme, for each target pulse grid point, generating a pulse polarity value corresponding to the target pulse grid point according to the pulse time and a pulse polarity judgment function corresponding to the target pulse grid point; determining a first pulse code corresponding to the pulse polarity value according to the pulse polarity value and multiple polarity value ranges; and generating a first single flux quantum sequence according to the n first pulse codes corresponding to the n target pulse grid points.

[0042] Figure 1 A diagram showing an application scenario of a method for generating a single magnetic flux quantum sequence according to an embodiment of the present invention is shown.

[0043] Figure 1 An exemplary system architecture of a single-flux quantum sequence generation method according to an embodiment of the present invention is shown.

[0044] like Figure 1 As shown, the system architecture 100 according to this embodiment may include a first terminal device 101, a second terminal device 102, a third terminal device 103, a network 104, and a server 105. The network 104 is used to provide a medium for a communication link between the first terminal device 101, the second terminal device 102, the third terminal device 103, and the server 105. The network 104 may include various connection types, such as wired and / or wireless communication links, etc.

[0045] The user can use the first terminal device 101 , the second terminal device 102 , and the third terminal device 103 to interact with the server 105 through the network 104 to receive or send messages, etc.

[0046] The first terminal device 101, the second terminal device 102, and the third terminal device 103 may be various electronic devices having display screens and supporting web browsing.

[0047] It should be noted that the single-flux quantum sequence generation method provided in the embodiment of the present invention can generally be executed by the server 105. Accordingly, the generation method of the single-qubit gate provided in the embodiment of the present invention can generally be executed by the server 105. The single-flux quantum sequence generation method provided in the embodiment of the present invention can also be executed by a server or server cluster that is different from the server 105 and can communicate with the first terminal device 101, the second terminal device 102, the third terminal device 103 and / or the server 105. Correspondingly, the generation method of the single-qubit gate provided in the embodiment of the present invention can also be executed by a server or server cluster that is different from the server 105 and can communicate with the first terminal device 101, the second terminal device 102, the third terminal device 103 and / or the server 105. Alternatively, the single-flux quantum sequence generation method provided in the embodiment of the present invention can also be executed by the first terminal device 101, the second terminal device 102 or the third terminal device 103, or by other terminal devices different from the first terminal device 101, the second terminal device 102 or the third terminal device 103. Correspondingly, the method for generating a single quantum bit gate provided in an embodiment of the present invention may also be executed by a server or server cluster that is different from the server 105 and that can communicate with the first terminal device 101, the second terminal device 102, the third terminal device 103 and / or the server 105.

[0048] It should be understood that Figure 1 The number of terminal devices, networks and servers in the embodiment is only for illustration. Any number of terminal devices, networks and servers may be provided according to the implementation requirements.

[0049] Figure 2 A flow chart of a method for generating a single magnetic flux quantum sequence according to an embodiment of the present invention is shown.

[0050] like Figure 2 As shown, the method 200 for generating a single magnetic flux quantum sequence includes operations S210 to S250.

[0051] In operation S210, in response to a sequence generation instruction, m discrete sequences are generated according to input waveform parameters.

[0052] In operation S220, n target pulse grid points and a pulse time corresponding to each target pulse grid point are determined according to the waveform integration values ​​of the m waveform points.

[0053] In operation S230, when the preset coding scheme is the envelope-integrated pulse coding scheme, for each target pulse grid point, a pulse polarity value corresponding to the target pulse grid point is generated according to the pulse time corresponding to the target pulse grid point and the pulse polarity judgment function.

[0054] In operation S240, a first pulse code corresponding to the pulse polarity value is determined according to the pulse polarity value and a plurality of polarity value ranges.

[0055] In operation S250, a first single flux quantum sequence is generated according to n first pulse codes corresponding to n target pulse grid points.

[0056] According to an embodiment of the present invention, the waveform parameters may include waveform frequency and / or waveform amplitude, and the guide waveform may include an envelope function.

[0057] According to an embodiment of the present invention, a guide waveform may be generated according to input waveform parameters. The guide waveform may be characterized as a waveform composed of multiple pulses, with a pulse interval between each pulse. The target pulse grid point may be a time instant that is an integer multiple of the pulse interval.

[0058] According to an embodiment of the present invention, each discrete sequence may include a waveform point, a waveform integral value, and a waveform time. m discrete sequences may include m waveform points, m waveform integral values, and m waveform times.

[0059] According to an embodiment of the present invention, the waveform point may be a target pulse grid point or may not be a target pulse grid point. The number n of target pulse grid points is less than or equal to the number m of waveform points. When the target pulse grid points are determined, the pulse time corresponding to each target pulse grid point may be determined, where m and n are both integers greater than or equal to 1.

[0060] According to an embodiment of the present invention, when the preset coding scheme is an envelope-integrated pulse coding scheme and n target pulse grid points are determined from m waveform points, a pulse polarity value corresponding to the target pulse grid point can be generated for each target pulse grid point based on the pulse time and pulse polarity judgment function corresponding to the target pulse grid point.

[0061] According to an embodiment of the present invention, the pulse polarity judgment function , as shown in formula (1):

[0062] (1)

[0063] in, is the pulse polarity value, f is the frequency of the superconducting bit f01 energy level, is the first initial phase, that is, the initial phase at time zero, is a parameter introduced to control the z error, t is the pulse time corresponding to the target pulse grid point, is the gate duration of a single-qubit gate.

[0064] According to an embodiment of the present invention, the polarity value range may include multiple values, for example, may include values ​​greater than or equal to a preset threshold, less than or equal to a negative preset threshold, greater than a negative preset threshold and less than a preset threshold.

[0065] According to an embodiment of the present invention, the pulse polarity value may be compared with a plurality of polarity value ranges to determine which polarity value range the pulse polarity value belongs to.

[0066] According to an embodiment of the present invention, each pulse polarity value range may correspond to a code, that is, when determining which polarity value range a pulse polarity value belongs to, the first pulse code corresponding to the pulse polarity value may be determined according to the polarity value range determined by the pulse polarity value.

[0067] According to an embodiment of the present invention, n target pulse grid points are determined according to waveform integral values ​​of m waveform points, and a pulse polarity value corresponding to each target pulse grid point is generated according to a pulse time and a pulse polarity judgment function corresponding to the target pulse grid point. The pulse polarity value corresponding to each target pulse grid point is compared with a plurality of polarity value ranges to determine a first pulse code corresponding to the pulse polarity value. A first single magnetic flux quantum sequence is generated according to n first pulse codes corresponding to the n target pulse grid points, thereby simplifying a method for generating a single magnetic flux quantum sequence, improving the generation efficiency of a single magnetic flux quantum sequence, and saving computing resources.

[0068] According to an embodiment of the present invention, m discrete sequences are generated according to input waveform parameters, including: generating a guide waveform according to the waveform parameters, the guide waveform including an envelope function; performing time integration processing on the envelope function to obtain m discrete sequences.

[0069] According to an embodiment of the present invention, a guide waveform may be generated according to waveform parameters. The guide waveform may include an envelope function. As shown in formula (3):

[0070] (3)

[0071] Where t is the waveform time.

[0072] According to an embodiment of the present invention, the envelope function can represent a pulse sequence at discrete time points. There is a pulse interval between each pulse sequence. By performing time integration processing on the envelope function, m discrete sequences can be obtained.

[0073] According to an embodiment of the present invention, n target pulse grid points and a pulse time corresponding to each target pulse grid point are determined based on waveform integral values ​​of m waveform points, including: for the ith waveform point, a cumulative integral value of the ith waveform point is generated based on the waveform integral values ​​of the previous i waveform points; when the waveform time of the ith waveform point satisfies a preset time condition, the ith waveform point is determined as an initial pulse grid point; when the cumulative integral value of the initial pulse grid point satisfies a preset integral variable, the initial pulse grid point is determined as a target pulse grid point, the waveform time corresponding to the initial pulse grid point is determined as the pulse time, and a new cumulative integral value corresponding to the ith waveform point is generated based on the cumulative integral value of the initial pulse grid point and the preset integral variable.

[0074] According to an embodiment of the present invention, for the i-th waveform point, the cumulative integral value of the i-th waveform point may be generated according to the waveform integral values ​​of the first i waveform points, where i is an integer greater than 1. For example, for the third waveform point, the cumulative integral value of the third waveform point may be generated according to the waveform integral values ​​of the first three waveform points.

[0075] According to an embodiment of the present invention, the preset time condition may be generated according to the pulse interval, and the moment satisfying the preset time condition may be called a grid point, and the grid point may be a moment that is an integer multiple of the pulse interval.

[0076] According to an embodiment of the present invention, when the waveform time at the i-th waveform point satisfies a preset time condition, that is, when the waveform time at the i-th waveform point is an integer multiple of the pulse interval, the i-th waveform point can be determined as an initial pulse grid point.

[0077] According to an embodiment of the present invention, the preset integral variable can be set according to demand, and the range of the preset integral variable may include 10ps~20ps. For example, the preset integral variable is set to 15ps, and when the cumulative integral value of the initial pulse grid point meets the preset integral variable, that is, when the cumulative integral value of the initial pulse grid point is greater than or equal to 15ps, the initial pulse grid point can be determined as a target pulse grid point. By adjusting the preset integral variable, the pulse interval can be adjusted, that is, the pulse density can be adjusted.

[0078] According to an embodiment of the present invention, the waveform time corresponding to the initial pulse grid point may be determined as the pulse time, and a new cumulative integral value corresponding to the i-th waveform point may be generated according to the cumulative integral value of the initial pulse grid point and a preset integral variable. For example, the preset integral variable may be subtracted from the cumulative integral value of the initial pulse grid point to obtain a new cumulative integral value corresponding to the i-th waveform point.

[0079] According to an embodiment of the present invention, the cumulative integral value of the ith waveform point can be obtained by accumulating the waveform integral values ​​of the first i waveform points, and when the cumulative integral value of the initial pulse grid point satisfies the preset integral variable, it can be determined as the target pulse grid point, and the cumulative integral value corresponding to the ith waveform point is updated. By determining the target pulse grid point, the amount of data for determining the first pulse code can be reduced.

[0080] According to an embodiment of the present invention, a cumulative integral value of an i-th waveform point is generated based on the waveform integral values ​​of the first i waveform points, including: when i is equal to 1, determining the waveform integral value of the i-th waveform point as the cumulative integral value of the i-th waveform point; when i is greater than 1, generating the cumulative integral value of the i-th waveform point based on the waveform integral value of the i-th waveform point and the target cumulative integral value of the i-1-th waveform point.

[0081] According to an embodiment of the present invention, when i is equal to 1, it can be determined that there is only one waveform point, and therefore, the waveform integral value of the first waveform point can be determined as the accumulated integral value of the first waveform point.

[0082] According to an embodiment of the present invention, the target cumulative integral value may include the cumulative integral value of the i-1th waveform point or a new cumulative integral value. When i is greater than 1, it may be characterized as including multiple waveform points, for example, including 10 waveform points, and the cumulative integral value of the 10th waveform point may be generated according to the waveform integral value of the 10th waveform point and the target cumulative integral value of the 9th waveform point.

[0083] According to an embodiment of the present invention, the cumulative integral value of the ith waveform point can be determined based on the waveform integral value of the ith waveform point and the target cumulative integral value of the i-1th waveform point. When the cumulative integral value of the waveform point is greater than or equal to a preset integral variable, it can be considered that the waveform point may be a target pulse grid point, thereby reducing the amount of data for determining the first pulse code.

[0084] According to an embodiment of the present invention, a first pulse code corresponding to a pulse polarity value is determined based on a pulse polarity value and a plurality of polarity value ranges, including: generating a first pulse sub-code when the pulse polarity value satisfies a first value range; generating a second pulse sub-code when the pulse polarity value satisfies a second value range; and generating a third pulse sub-code when the pulse polarity value satisfies a third value range.

[0085] According to an embodiment of the present invention, the plurality of polarity value ranges may include a first value range, a second value range and a third value range. For example, the first value range may be greater than or equal to 0.5, the second value range may be less than 0.5 and greater than -0.5, and the third value range may be less than or equal to -0.5.

[0086] According to an embodiment of the present invention, the first pulse code may include a first pulse sub-code, a second pulse sub-code or a third pulse sub-code. The pulse memory value can only satisfy any one of a plurality of polarity values. Each polarity value range may correspond to a pulse sub-code.

[0087] According to an embodiment of the present invention, when the pulse polarity value satisfies the first numerical range, a first pulse sub-code may be generated. For example, the first pulse sub-code may be a positive single flux quantum sequence pulse. When the pulse polarity value satisfies the second numerical range, a second pulse sub-code may be generated. For example, the second pulse sub-code may be a zero single flux quantum sequence pulse. When the pulse polarity value satisfies the third numerical range, a third pulse sub-code may be generated. For example, the third pulse sub-code may be a negative single flux quantum sequence pulse.

[0088] According to an embodiment of the present invention, by comparing the pulse polarity value and multiple polarity value ranges, when the pulse polarity value satisfies different polarity value ranges, different pulse sub-codes can be corresponding, thereby obtaining a first pulse code composed of multiple pulse sub-codes. According to the first pulse code, a first single magnetic flux quantum sequence can be generated, thereby simplifying the generation method of the single magnetic flux quantum sequence and improving the generation efficiency of the single magnetic flux quantum sequence.

[0089] According to an embodiment of the present invention, the above-mentioned method for generating a single flux quantum sequence also includes: when the preset coding scheme is a mixing-based pulse coding scheme, for each target pulse grid point, according to the pulse time and pulse polarity guidance function corresponding to the target pulse grid point, a pulse guidance value corresponding to the target pulse grid point is generated; according to the pulse guidance value and multiple guidance value ranges, a second pulse code corresponding to the pulse guidance value is determined; according to the n second pulse codes corresponding to the n target pulse grid points, a second single flux quantum sequence is generated.

[0090] According to an embodiment of the present invention, when the preset coding scheme is a mixing-based pulse coding scheme, for each target pulse grid point, a pulse time and pulse polarity guidance function corresponding to the target pulse grid point can be used to generate a pulse guidance value corresponding to the target pulse grid point.

[0091] According to an embodiment of the present invention, the pulse polarity guidance function is shown in formula (2):

[0092] (2)

[0093] in, is the pulse guidance value, f is the frequency of the superconducting bit f01 energy level, is the second initial phase, is the third initial phase, is the preset parameter, and They are the first frequency and the second frequency respectively, that is, the frequencies between the bit energy levels 01 and 12.

[0094] According to an embodiment of the present invention, the guide value range may include multiple guide value ranges, and the pulse guide value is compared with the multiple guide value ranges to determine which guide value range of the multiple guide value ranges the pulse guide value belongs to, so that the second pulse code corresponding to the pulse guide value can be determined.

[0095] According to an embodiment of the present invention, when the preset coding scheme is a mixing-based pulse coding scheme, a pulse guiding value corresponding to a target pulse grid point can be determined based on a pulse polarity guiding function, and the pulse guiding value can be compared with a plurality of guiding value ranges, and the guiding value range to which the pulse guiding value belongs can be determined from the plurality of guiding value ranges, and then a second pulse coding corresponding to the pulse guiding value is determined, and n second codings generate a second single flux quantum sequence, which simplifies the method for generating a single flux quantum sequence and improves the generation efficiency of a single flux quantum sequence.

[0096] According to an embodiment of the present invention, a second pulse code corresponding to the pulse guide value is determined based on the pulse guide value and multiple guide value ranges, including: generating a fourth pulse sub-code when the pulse guide value satisfies a fourth value range; generating a fifth pulse sub-code when the pulse guide value satisfies a fifth value range; and generating a sixth pulse sub-code when the pulse guide value satisfies a sixth value range.

[0097] According to an embodiment of the present invention, the plurality of guide value ranges may include a fourth value range, a fifth value range, and a sixth value range. The pulse guide value may belong to any one of the fourth value range, the fifth value range, and the sixth value range. For example, the pulse guide value may belong to the fourth value range.

[0098] According to an embodiment of the present invention, the second pulse coding may include a fourth pulse sub-coding, a fifth pulse sub-coding or a sixth pulse sub-coding, and each pulse guide value range may correspond to a pulse sub-coding.

[0099] According to an embodiment of the present invention, when the pulse guidance value satisfies the fourth numerical range, a fourth pulse sub-code may be generated. For example, the fourth pulse sub-code may be a positive single flux quantum sequence pulse. When the pulse guidance value satisfies the fifth numerical range, a fifth pulse sub-code may be generated. For example, the fifth pulse sub-code may be a zero single flux quantum sequence pulse. When the pulse guidance value satisfies the sixth numerical range, a sixth pulse sub-code may be generated. For example, the sixth pulse sub-code may be a negative single flux quantum sequence pulse.

[0100] According to an embodiment of the present invention, by comparing a pulse guide value and a plurality of guide value ranges, when the pulse guide value satisfies different guide value ranges, different pulse sub-codes may correspond, thereby obtaining a second pulse code composed of a plurality of pulse sub-codes. According to the second pulse code, a second single magnetic flux quantum sequence may be generated, thereby simplifying the generation method of the single magnetic flux quantum sequence, improving the generation efficiency of the single magnetic flux quantum sequence, and saving computing resources.

[0101] According to an embodiment of the present invention, the above-mentioned method for generating a single flux quantum sequence also includes: adjusting the first initial phase or the second initial phase to continuously control the phase of the single quantum bit gate; and / or adjusting the preset parameters and the third initial phase to control the target state leakage during the gate action of the single quantum bit gate; and / or adjusting the first frequency to control the Z error during the gate action of the single quantum bit gate.

[0102] According to an embodiment of the present invention, a single-qubit gate may represent a gate acting on a single qubit. By adjusting the first initial phase or the second initial phase, the phase of the single-qubit gate may be continuously controlled.

[0103] According to an embodiment of the present invention, target state leakage can characterize the phenomenon that two computational states of a quantum bit leak out to other non-computational states. For example, target state leakage can be 2-state leakage. By adjusting the preset parameters and the third initial phase, it is possible to control the target state leakage during the gate action of a single quantum bit gate, thereby achieving high fidelity of a single quantum bit gate.

[0104] According to an embodiment of the present invention, the Z error during the gate action process can characterize the phase flip error of the quantum bit. By adjusting the first frequency, the Z error during the gate action process of the single quantum bit gate can be controlled, and the probability of the Z error during the gate action process of the single quantum bit gate can be reduced.

[0105] According to an embodiment of the present invention, when the preset parameters are 0, the first frequency is selected to be approximately the frequency of the superconducting bit f01 energy level. By scanning the boundary values ​​of the numerical range, the boundary values ​​of the numerical range that make the single quantum bit gate rotate approximately by 0.5π can be determined.

[0106] According to an embodiment of the present invention, when the preset parameter is 0 and a single-qubit gate phase is fixed, the first initial phase can be scanned so that the gate phase corresponding to the guide waveform is aligned with the single-qubit gate.

[0107] According to an embodiment of the present invention, when the preset parameter is 0, the Z error in the gate action process of the single-qubit gate can be eliminated by fine-tuning the first frequency.

[0108] According to an embodiment of the present invention, the rotation angle of the single-qubit gate can be adjusted by adjusting a preset integral variable.

[0109] According to the embodiment of the present invention, by adjusting various parameters, a single magnetic flux quantum sequence can be quickly obtained without involving algorithm optimization, thus saving computing resources and having strong feasibility in experiments.

[0110] Based on the above single flux quantum sequence generation method, the present invention also provides a method for generating a single quantum bit gate. Figure 3 The method is described in detail.

[0111] Figure 3 A flow chart of a method for generating a single quantum bit gate according to an embodiment of the present invention is shown.

[0112] like Figure 3 As shown, the method 300 for generating a single quantum bit gate includes operations S310 to S350.

[0113] In operation S310, a single flux quantum sequence is acquired.

[0114] In operation S320 , a control square wave sequence is generated using a digital voltage source based on the single flux quantum sequence.

[0115] In operation S330 , a single magnetic flux pulse generating circuit is used to process and control the square wave sequence to generate a single magnetic flux pulse signal.

[0116] In operation S340 , a single magnetic flux pulse signal is applied to the qubit to drive a target energy level reversal of the qubit, and the fidelity of the qubit is calculated.

[0117] In operation S350, the waveform parameters of the single flux pulse signal are iteratively optimized according to the fidelity, so that the optimized single flux pulse signal acts on the quantum bit, thereby generating a single quantum bit gate.

[0118] According to an embodiment of the present invention, the target energy level may be a 01 energy level. By applying a single magnetic flux pulse signal to a quantum bit, the 01 energy level reversal of the quantum bit may be achieved.

[0119] According to an embodiment of the present invention, the waveform parameters of the single flux pulse signal can be optimized according to the fidelity, and the optimized single flux pulse signal can be applied to the quantum bit, so that a single quantum bit gate can be generated.

[0120] Figure 4A schematic diagram of a single magnetic flux quantum sequence generated by an envelope-integrated pulse coding scheme according to an embodiment of the present invention is shown. Figure 5 A schematic diagram of a single magnetic flux quantum sequence generated by a filtered envelope-integrated pulse coding scheme according to an embodiment of the present invention is shown. Figure 6 A schematic diagram showing the fidelity of adjusting the phase of a single-qubit gate using an envelope-integrated pulse coding scheme according to an embodiment of the present invention is shown.

[0121] According to an embodiment of the present invention, each target pulse grid point may correspond to a first pulse code, and therefore, a first single magnetic flux quantum sequence may be generated according to n first pulse codes corresponding to n target pulse grid points. In one embodiment, in the case of an envelope-integrated pulse coding scheme, the first single magnetic flux quantum sequence may be as follows: Figure 4 As shown. Figure 4 The first single flux quantum sequence shown is filtered by a 2~8G bandpass filter. Figure 5 In the case of the envelope-integrated pulse coding scheme, when the phase of the single-qubit gate is adjusted only by changing the first initial phase, the fidelity diagram is shown as Figure 6 shown.

[0122] Figure 7 A schematic diagram of a single magnetic flux quantum sequence generated by a frequency mixing-based pulse coding scheme according to an embodiment of the present invention is shown. Figure 8 A schematic diagram of a single magnetic flux quantum sequence generated by a filtered mixing-based pulse coding scheme according to an embodiment of the present invention is shown.

[0123] According to an embodiment of the present invention, a second single magnetic flux quantum sequence may be generated according to n second pulse codes corresponding to n target pulse grid points. In one embodiment, the second single magnetic flux quantum sequence may be as follows: Figure 7 As shown. Figure 7 The second single flux quantum sequence shown in FIG. 1 is filtered by a 2~8G bandpass filter. Figure 8 shown.

[0124] Fig. 9 A schematic diagram of a two-qubit circuit according to an embodiment of the present invention is shown.

[0125] like Fig. 9 As shown, the dual quantum bit circuit includes a first capacitor C q1c , the second capacitor C q1q2 , the third capacitor C q2c , the first quantum bit Q1, the second quantum bit Q2 and the coupling bit coupler.

[0126] According to an embodiment of the present invention, the first quantum bit Q1 includes a first Josephson junction pair and a fourth capacitor C q1The second quantum bit Q2 includes a second Josephson junction pair and a fifth capacitor C q2 The coupling bit coupler includes a third Josephson junction pair and a sixth capacitor C c .w c Represents the energy level difference between the 0 state and the 1 state.

[0127] According to an embodiment of the present invention, by injecting a single magnetic flux pulse signal into the first inductor L1 and the third inductor L3, the single magnetic flux pulse signal acts on two qubits, thereby driving the target energy level of the qubit to be reversed. The waveform parameters of the single magnetic flux pulse signal are optimized according to the calculated fidelity, and the optimized single magnetic flux pulse signal is applied to the qubit, thereby generating a more accurate single qubit gate.

[0128] Fig.10 A block diagram of an electronic device suitable for implementing a method for generating a single-flux quantum sequence and a method for generating a single-qubit gate according to an embodiment of the present invention is shown.

[0129] like Fig.10 As shown, the electronic device 1000 according to an embodiment of the present invention includes a processor 1001, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 1002 or a program loaded from a storage part 1008 into a random access memory (RAM) 1003. The processor 1001 may include, for example, a general-purpose microprocessor (e.g., a CPU), an instruction set processor and / or a related chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 1001 may also include an onboard memory for caching purposes. The processor 1001 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of the present invention.

[0130] In RAM 1003, various programs and data required for the operation of electronic device 1000 are stored. Processor 1001, ROM 1002 and RAM 1003 are connected to each other via bus 1004. Processor 1001 performs various operations of the method flow according to the embodiment of the present invention by executing the program in ROM 1002 and / or RAM 1003. It should be noted that the program can also be stored in one or more memories other than ROM 1002 and RAM 1003. Processor 1001 can also perform various operations of the method flow according to the embodiment of the present invention by executing the program stored in the one or more memories.

[0131] According to an embodiment of the present invention, the electronic device 1000 may further include an input / output (I / O) interface 1005, which is also connected to the bus 1004. The electronic device 1000 may further include one or more of the following components connected to the I / O interface 1005: an input portion 1006 including a keyboard, a mouse, etc.; an output portion 1007 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage portion 1008 including a hard disk, etc.; and a communication portion 1009 including a network interface card such as a LAN card, a modem, etc. The communication portion 1009 performs communication processing via a network such as the Internet. A drive 1010 is also connected to the I / O interface 1005 as needed. A removable medium 1011, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 1010 as needed, so that a computer program read therefrom is installed into the storage portion 1008 as needed.

[0132] The present invention also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiment; or may exist independently without being assembled into the device / apparatus / system. The above computer-readable storage medium carries one or more programs, and when the above one or more programs are executed, the method according to the embodiment of the present invention is implemented.

[0133] According to an embodiment of the present invention, the computer-readable storage medium may be a non-volatile computer-readable storage medium, for example, it may include but is not limited to: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present invention, the computer-readable storage medium may be any tangible medium containing or storing a program, which may be used by or in combination with an instruction execution system, an apparatus or a device. For example, according to an embodiment of the present invention, the computer-readable storage medium may include the ROM 1002 and / or RAM 1003 described above and / or one or more memories other than ROM 1002 and RAM 1003.

[0134] The embodiment of the present invention also includes a computer program product, which includes a computer program, and the computer program contains program code for executing the method shown in the flowchart. When the computer program product is run in a computer system, the program code is used to enable the computer system to implement the method provided by the embodiment of the present invention.

[0135] The computer program executes the above functions defined in the system / device of the embodiment of the present invention when it is executed by the processor 1001. According to the embodiment of the present invention, the system, device, module, unit, etc. described above can be implemented by a computer program module.

[0136] In one embodiment, the computer program may rely on tangible storage media such as optical storage devices, magnetic storage devices, etc. In another embodiment, the computer program may also be transmitted and distributed in the form of signals on a network medium, and downloaded and installed through the communication part 1009, and / or installed from the removable medium 1011. The program code contained in the computer program may be transmitted using any appropriate network medium, including but not limited to: wireless, wired, etc., or any suitable combination of the above.

[0137] In such an embodiment, the computer program can be downloaded and installed from the network through the communication part 1009, and / or installed from the removable medium 1011. When the computer program is executed by the processor 1001, the above functions defined in the system of the embodiment of the present invention are performed. According to the embodiment of the present invention, the system, device, means, module, unit, etc. described above can be implemented by a computer program module.

[0138] According to an embodiment of the present invention, the program code for executing the computer program provided by the embodiment of the present invention can be written in any combination of one or more programming languages. Specifically, these computing programs can be implemented using high-level process and / or object-oriented programming languages, and / or assembly / machine languages. Programming languages ​​include, but are not limited to, Java, C++, python, "C" language or similar programming languages. The program code can be executed entirely on the user computing device, partially on the user device, partially on the remote computing device, or entirely on the remote computing device or server. In the case of a remote computing device, the remote computing device can be connected to the user computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computing device (e.g., using an Internet service provider to connect through the Internet).

[0139] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present invention. In this regard, each box in the flowchart or block diagram may represent a module, a program segment, or a part of a code, and the above-mentioned module, program segment, or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box may also occur in an order different from the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions. It can be understood by those skilled in the art that the features recorded in the various embodiments of the present invention can be combined and / or combined in various ways, even if such a combination or combination is not explicitly recorded in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features recorded in the various embodiments of the present invention can be combined and / or combined in various ways. All these combinations and / or combinations fall within the scope of the present invention.

[0140] The embodiments of the present invention are described above. However, these embodiments are only for the purpose of illustration, and are not intended to limit the scope of the present invention. Although each embodiment is described above, it does not mean that the measures in each embodiment cannot be used in combination advantageously. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A method for generating a single flux quantum sequence, characterized in that: include: In response to the sequence generation instruction, m discrete sequences are generated according to the input waveform parameters, wherein each of the discrete sequences includes a waveform point, a waveform integral value, and a waveform time; Determining n target pulse grid points and a pulse time corresponding to each target pulse grid point according to the waveform integral values ​​of the m waveform points; In the case where the preset coding scheme is an envelope integral pulse coding scheme, for each of the target pulse grid points, a pulse polarity value corresponding to the target pulse grid point is generated according to a pulse time and a pulse polarity judgment function corresponding to the target pulse grid point; Determining a first pulse code corresponding to the pulse polarity value according to the pulse polarity value and a plurality of polarity value ranges; A first single magnetic flux quantum sequence is generated according to the n first pulse codes corresponding to the n target pulse grid points, wherein m and n are both integers greater than or equal to 1.

2. The method according to claim 1, characterized in that The step of generating m discrete sequences according to the input waveform parameters comprises: generating a guide waveform according to the waveform parameters, wherein the waveform parameters include waveform frequency and / or waveform amplitude, and the guide waveform includes an envelope function; Performing time integration processing on the envelope function to obtain m discrete sequences.

3. The method according to claim 1, characterized in that The step of determining n target pulse grid points and a pulse time corresponding to each target pulse grid point according to the waveform integral values ​​of the m waveform points comprises: For the i-th waveform point, generating a cumulative integral value of the i-th waveform point according to the waveform integral values ​​of the previous i waveform points, where i is an integer greater than 1; When the waveform time of the i-th waveform point meets a preset time condition, determining the i-th waveform point as an initial pulse grid point; When the accumulated integral value of the initial pulse grid point satisfies the preset integral variable, the initial pulse grid point is determined as the target pulse grid point, the waveform time corresponding to the initial pulse grid point is determined as the pulse time, and a new accumulated integral value corresponding to the i-th waveform point is generated based on the accumulated integral value of the initial pulse grid point and the preset integral variable.

4. The method according to claim 3, characterized in that The step of generating the cumulative integral value of the i-th waveform point according to the waveform integral values ​​of the first i waveform points includes: When i is equal to 1, the waveform integral value of the i-th waveform point is determined as the accumulated integral value of the i-th waveform point; When i is greater than 1, the cumulative integral value of the i-th waveform point is generated based on the waveform integral value of the i-th waveform point and the target cumulative integral value of the i-1-th waveform point, wherein the target cumulative integral value includes the cumulative integral value of the i-1-th waveform point or the new cumulative integral value.

5. The method according to claim 1, characterized in that The plurality of polarity value ranges include a first value range, a second value range, and a third value range; Wherein, determining the first pulse code corresponding to the pulse polarity value according to the pulse polarity value and multiple polarity value ranges includes: When the pulse polarity value satisfies the first value range, generating a first pulse sub-code; When the pulse polarity value satisfies the second value range, generating a second pulse sub-code; When the pulse polarity value satisfies the third value range, a third pulse sub-code is generated, wherein the first pulse code includes the first pulse sub-code, the second pulse sub-code or the third pulse sub-code.

6. The method according to claim 1, characterized in that Also includes: In the case where the preset coding scheme is a mixing-based pulse coding scheme, for each of the target pulse grid points, a pulse guidance value corresponding to the target pulse grid point is generated according to a pulse time and a pulse polarity guidance function corresponding to the target pulse grid point; Determine a second pulse code corresponding to the pulse guide value according to the pulse guide value and a plurality of guide value ranges; A second single magnetic flux quantum sequence is generated according to the n second pulse codes corresponding to the n target pulse grid points.

7. The method according to claim 6, characterized in that The plurality of guide numerical ranges include a fourth numerical range, a fifth numerical range, and a sixth numerical range; The step of determining a second pulse code corresponding to the pulse guide value according to the pulse guide value and a plurality of guide value ranges includes: When the pulse guide value satisfies the fourth value range, generating a fourth pulse sub-code; When the pulse guide value satisfies the fifth value range, generating a fifth pulse sub-code; When the pulse guide value satisfies the sixth value range, a sixth pulse sub-code is generated, wherein the second pulse code includes the fourth pulse sub-code, the fifth pulse sub-code or the sixth pulse sub-code.

8. The method according to claim 6, characterized in that The pulse polarity judgment function is shown in formula (1), and the pulse polarity guidance function is shown in formula (2): （1）； （2）； in, is the pulse polarity value, is the pulse guidance value, f is the frequency of the superconducting bit f01 energy level, is the first initial phase, that is, the initial phase at time zero, is the second initial phase, is the third initial phase, is the preset parameter, is the parameter introduced to control the Z error, t is the pulse time corresponding to the target pulse grid point, is the first frequency, is a second frequency, the first frequency and the second frequency both belong to bit 01 energy level and bit 12 energy level, is the gate duration of a single-qubit gate.

9. The method according to claim 8, characterized in that Also includes: adjusting the first initial phase or the second initial phase to continuously control the phase of the single-qubit gate; and / or Adjusting the preset parameters and the third initial phase to control target state leakage during the gate action of the single quantum bit gate; and / or The first frequency is adjusted to control Z errors during gate action of the single quantum bit gate.

10. A method for generating a single quantum bit gate, comprising: Obtaining a single magnetic flux quantum sequence as described in any one of claims 1 to 9; Based on the single magnetic flux quantum sequence, a control square wave sequence is generated using a digital voltage source; Processing the control square wave sequence using a single magnetic flux pulse generating circuit to generate a single magnetic flux pulse signal; Applying the single magnetic flux pulse signal to a quantum bit to drive a target energy level reversal of the quantum bit, and calculating the fidelity of the quantum bit; The waveform parameters of the single flux pulse signal are iteratively optimized according to the fidelity, so that the optimized single flux pulse signal acts on the quantum bit, thereby generating the single quantum bit gate.

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