A quantum voltage output control method and device based on Josephson array

Abstract

The invention discloses a quantum voltage output control method and device based on a Josephson array, which are applied to a quantum voltage synthesis system based on a Josephson array. The method comprises: receiving an array scanning control signal; controlling the quantum voltage synthesis system to perform zero-step scanning according to the array scanning control signal to obtain a zero-step boundary; controlling the quantum voltage synthesis system to perform positive and negative step scanning according to the zero-step boundary to obtain a positive and negative step I-V characteristic curve; receiving a quantum voltage output request signal; calculating a quantum voltage control parameter according to the quantum voltage output request signal and the positive and negative step I-V characteristic curve; and controlling the quantum voltage synthesis system to output a quantum voltage signal according to the quantum voltage control parameter. The method can improve the accuracy of quantum voltage output.

Description

Technical Field

[0001] The present invention relates to the field of measurement, and in particular to a quantum voltage output control method and device based on a Josephson array. Background Art

[0002] The Josephson junction is a superconductor quantum device based on the Josephson effect, which has important applications in the field of superconducting electronics. This device integrates several to tens of thousands of Josephson junctions on a single chip to form a Josephson junction array. Under specific microwave radiation conditions, these junction arrays can generate stable voltage signals under the action of DC bias current. Due to its extremely high voltage stability and accuracy, the Josephson junction array has become a key technical component for building a quantum voltage reference. For example, patent text CN110095639A discloses an AC quantum voltage generation device, including a host computer, a clock, a drive circuit, a digital voltmeter, a microwave source, a cryogenic probe, a cryogenic dewar and a PJVS junction array, wherein: the host computer is connected to the clock, the drive circuit, the digital voltmeter (DVM) and the microwave source, and the host computer controls the drive circuit to generate a drive current; the digital voltmeter is connected to the host computer and the cryogenic probe, and the digital voltmeter receives the instructions of the host computer, reads the voltage value when the PJVS junction array performs an IV characteristic scan, and then sends the read voltage value to the host computer for storage and analysis; the microwave source is connected to the host computer and the cryogenic probe , the microwave source generates microwave signals under the control of the host computer, and outputs the microwave signals to the PJVS array through the cryogenic probe, stimulating the PJVS array to generate quantum voltage; the clock is connected to the host computer, the drive circuit, the digital voltmeter and the microwave source, providing a working clock for the host computer, the drive circuit, the digital voltmeter and the microwave source; the cryogenic probe is connected to the drive circuit, the digital voltmeter, the microwave source and the PJVS array, and the cryogenic probe receives the switch control signal generated by the drive circuit to control the switching of the switch in the cryogenic probe; the cryogenic probe receives the drive current generated by the drive circuit and outputs it to the PJVS array, driving the PJVS array to generate a corresponding voltage value; the cryogenic Dewar provides low temperature for the PJVS array, so that the PJVS chip is in a superconducting state. The accuracy of the IV characteristic scan directly affects the accuracy of the quantum voltage output. Therefore, how to obtain a more accurate IV characteristic curve is an urgent problem to be solved. Summary of the invention

[0003] The present invention provides a quantum voltage output control method and device based on a Josephson array, which can improve the accuracy of quantum voltage output.

[0004] A quantum voltage output control method based on a Josephson junction array is applied to a quantum voltage synthesis system based on a Josephson junction array, and the method comprises:

[0005] Receive array scanning control signal;

[0006] Controlling the quantum voltage synthesis system to perform zero-step scanning according to the array scanning control signal to obtain a zero-step boundary;

[0007] According to the zero step boundary, controlling the quantum voltage synthesis system to perform positive and negative step scanning to obtain positive and negative step IV characteristic curves;

[0008] receiving a quantum voltage output request signal;

[0009] Calculating a quantum voltage control parameter according to the quantum voltage output request signal and the positive and negative step IV characteristic curve;

[0010] The quantum voltage synthesis system is controlled to output a quantum voltage signal according to the quantum voltage control parameter.

[0011] Furthermore, the quantum voltage synthesis system includes a bias system, a cryogenic system, a microwave source and a Josephson array, and the Josephson array includes a plurality of array units.

[0012] Furthermore, the method further comprises:

[0013] Receive array protection control signal;

[0014] According to the array protection control signal, the output power of the microwave source is controlled to be the lowest, the bias current output by the bias system is controlled to be 0, and the Josephson array is short-circuited.

[0015] Further, controlling the quantum voltage synthesis system to perform zero-step scanning according to the array scanning control signal to obtain a zero-step boundary includes:

[0016] Controlling the output power of the microwave source to be the lowest, and setting a first bias current scanning step length;

[0017] Starting from 0, controlling the bias system to increase the output bias current in sequence according to the first bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current and calculating the output voltage variation, and stopping scanning when the output voltage variation exceeds a preset threshold;

[0018] Judging whether the corresponding array unit loses its superconducting property according to a first variation curve of the output voltage as the bias current varies;

[0019] If the array unit has not lost its superconducting property, a zero step boundary is determined according to the first change curve.

[0020] Furthermore, if a step appears in the first variation curve of the output voltage with the bias current, it is determined that the corresponding array unit has not lost its superconducting property;

[0021] The step means that within a certain bias current range, the output voltage remains unchanged, and at both ends of the bias current range, the corresponding output voltage jumps;

[0022] The zero step boundary is a bias current corresponding to a starting point of the first step in the first variation curve.

[0023] Further, according to the zero step boundary, the quantum voltage synthesis system is controlled to perform positive and negative step scanning to obtain positive and negative step IV characteristic curves, including:

[0024] Controlling the output power of the microwave source to a preset value, setting a second bias current scanning step length, a third bias current scanning step length, and a fourth bias current scanning step length, wherein the second bias current scanning step length is greater than the third bias current scanning step length;

[0025] Taking the zero step boundary as the first scanning starting point, controlling the bias system to sequentially increase the output bias current according to the second bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current, obtaining a second variation curve of the output voltage with the bias current, and obtaining a second scanning starting point according to the second variation curve;

[0026] Starting from the second scanning starting point, controlling the bias system to sequentially increase the output bias current according to the third bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current, obtaining a third variation curve of the output voltage varying with the bias current, and obtaining a preset number of first current points to be calculated according to the third variation curve;

[0027] Starting from the second scanning starting point, controlling the bias system to sequentially reduce the output bias current according to the third bias current scanning step length and apply it to the array unit, detecting the output voltage of the array unit under each bias current, obtaining a fourth variation curve of the output voltage varying with the bias current, and obtaining a preset number of second current points to be calculated according to the fourth variation curve;

[0028] Calculate an average value of the second scanning starting point, a preset number of first current points to be calculated, and a second current point to be calculated, and use the average value as the left boundary of the positive step;

[0029] Taking the left boundary of the positive step as the third scanning starting point, controlling the bias system to increase the output bias current in sequence according to the fourth bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current and calculating the output voltage variation, stopping the scanning when the output voltage variation exceeds a preset threshold, obtaining a fifth variation curve of the output voltage varying with the bias current, and obtaining the positive step boundary and the positive step width according to the fifth variation curve;

[0030] Based on the principle of symmetry, the right boundary of the negative step, the negative step boundary and the negative step width are obtained according to the left boundary of the positive step, the positive step boundary and the positive step width;

[0031] The positive and negative step IV characteristic curves of the corresponding array unit are obtained according to the left boundary of the positive step, the positive step boundary, the positive step width, the right boundary of the negative step, the negative step boundary and the negative step width.

[0032] Further, the second scanning starting point is a bias current corresponding to a starting point of a first step in the second variation curve;

[0033] The preset number of first current points to be calculated are bias currents corresponding to starting points of a preset number of steps in the third variation curve;

[0034] The preset number of second current points to be calculated are bias currents corresponding to starting points of a preset number of steps in the fourth variation curve.

[0035] Furthermore, the bias currents corresponding to the left boundary of the positive step and the right boundary of the negative step are equal in magnitude and opposite in polarity, the bias current and output voltage corresponding to the positive step boundary and the bias current and output voltage corresponding to the negative step boundary are equal in magnitude and opposite in polarity; the positive step width is equal to the negative step width.

[0036] Further, according to the quantum voltage output request signal and the positive and negative step IV characteristic curve, the quantum voltage control parameter is calculated, including:

[0037] Obtaining a quantum voltage value to be output according to the quantum voltage output request signal;

[0038] According to the quantum voltage value to be output and the positive and negative step IV characteristic curve of each array unit, setting the bias state of each array unit;

[0039] Determining the bias current required for each array unit according to the positive and negative step IV characteristic curve;

[0040] Calculating the quantum voltage control parameter according to the bias current required by each array unit;

[0041] The quantum voltage control parameter is calculated by the following formula:

[0042] ;

[0043] (i=0,2...n-1);

[0044] Where n represents the number of array units, V bias(i)Indicates the value of the quantum voltage output corresponding to the i-th array unit, I bias(i) represents the bias current required by the i-th array unit, I DAC(i) represents the current input from the bias system to the i-th array unit, B i Indicates the bias state of the i-th array unit, and the value is 0, +1 or -1. 0 means that the array unit is in a zero bias state and there is no voltage output. +1 means that the array unit is in a positive bias state and the current direction is the same as the reference direction. -1 means that the array unit is in a negative bias state and the current direction is opposite to the reference direction. i represents the number of Josephson junctions contained in the i-th junction array unit, f0 represents the microwave frequency, K J-90 represents the Josephson constant, and R represents the resistance parameter in the bias system.

[0045] A quantum voltage output control device based on a Josephson array applied to the above method comprises:

[0046] A signal receiving module, used for receiving array scanning control signals;

[0047] A zero-step scanning control module, used to control the quantum voltage synthesis system to perform zero-step scanning according to the array scanning control signal to obtain a zero-step boundary;

[0048] A positive and negative step scanning control module, used to control the quantum voltage synthesis system to perform positive and negative step scanning according to the zero step boundary to obtain positive and negative step IV characteristic curves;

[0049] A request module, used for receiving a quantum voltage output request signal;

[0050] A control parameter calculation module, used to calculate the quantum voltage control parameter according to the quantum voltage output request signal and the positive and negative step IV characteristic curve;

[0051] A signal output control module is used to control the quantum voltage synthesis system to output a quantum voltage signal according to the quantum voltage control parameter.

[0052] Furthermore, the quantum voltage synthesis system includes a bias system, a cryogenic system, a microwave source and a Josephson array, and the Josephson array includes a plurality of array units.

[0053] Furthermore, the device also includes an array protection module, which is used to:

[0054] Receive array protection control signal;

[0055] According to the array protection control signal, the output power of the microwave source is controlled to be the lowest, the bias current output by the bias system is controlled to be 0, and the Josephson array is short-circuited.

[0056] Furthermore, the zero-step scanning control module controls the quantum voltage synthesis system to perform zero-step scanning according to the array scanning control signal to obtain a zero-step boundary, including:

[0057] Controlling the output power of the microwave source to be the lowest, and setting a first bias current scanning step length;

[0058] Starting from 0, controlling the bias system to increase the output bias current in sequence according to the first bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current and calculating the output voltage variation, and stopping scanning when the output voltage variation exceeds a preset threshold;

[0059] Judging whether the corresponding array unit loses its superconducting property according to a first variation curve of the output voltage as the bias current varies;

[0060] If the array unit has not lost its superconducting property, a zero step boundary is determined according to the first change curve.

[0061] Furthermore, if a step appears in the first variation curve of the output voltage with the bias current, it is determined that the corresponding array unit has not lost its superconducting property;

[0062] The step means that within a certain bias current range, the output voltage remains unchanged, and at both ends of the bias current range, the corresponding output voltage jumps;

[0063] The zero step boundary is a bias current corresponding to a starting point of the first step in the first variation curve.

[0064] Furthermore, the positive and negative step scanning control module controls the quantum voltage synthesis system to perform positive and negative step scanning according to the zero step boundary to obtain positive and negative step IV characteristic curves, including:

[0065] Controlling the output power of the microwave source to a preset value, setting a second bias current scanning step length, a third bias current scanning step length, and a fourth bias current scanning step length, wherein the second bias current scanning step length is greater than the third bias current scanning step length;

[0066] Taking the zero step boundary as the first scanning starting point, controlling the bias system to sequentially increase the output bias current according to the second bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current, obtaining a second variation curve of the output voltage with the bias current, and obtaining a second scanning starting point according to the second variation curve;

[0067] Starting from the second scanning starting point, controlling the bias system to sequentially increase the output bias current according to the third bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current, obtaining a third variation curve of the output voltage varying with the bias current, and obtaining a preset number of first current points to be calculated according to the third variation curve;

[0068] Starting from the second scanning starting point, controlling the bias system to sequentially reduce the output bias current according to the third bias current scanning step length and apply it to the array unit, detecting the output voltage of the array unit under each bias current, obtaining a fourth variation curve of the output voltage varying with the bias current, and obtaining a preset number of second current points to be calculated according to the fourth variation curve;

[0069] Calculate an average value of the second scanning starting point, a preset number of first current points to be calculated, and a second current point to be calculated, and use the average value as the left boundary of the positive step;

[0070] Taking the left boundary of the positive step as the third scanning starting point, controlling the bias system to increase the output bias current in sequence according to the fourth bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current and calculating the output voltage variation, stopping the scanning when the output voltage variation exceeds a preset threshold, obtaining a fifth variation curve of the output voltage varying with the bias current, and obtaining the positive step boundary and the positive step width according to the fifth variation curve;

[0071] Based on the principle of symmetry, the right boundary of the negative step, the negative step boundary and the negative step width are obtained according to the left boundary of the positive step, the positive step boundary and the positive step width;

[0072] The positive and negative step IV characteristic curves of the corresponding array unit are obtained according to the left boundary of the positive step, the positive step boundary, the positive step width, the right boundary of the negative step, the negative step boundary and the negative step width.

[0073] Further, the second scanning starting point is a bias current corresponding to a starting point of a first step in the second variation curve;

[0074] The preset number of first current points to be calculated are bias currents corresponding to starting points of a preset number of steps in the third variation curve;

[0075] The preset number of second current points to be calculated are bias currents corresponding to starting points of a preset number of steps in the fourth variation curve.

[0076] Furthermore, the bias currents corresponding to the left boundary of the positive step and the right boundary of the negative step are equal in magnitude and opposite in polarity, the bias current and output voltage corresponding to the positive step boundary and the bias current and output voltage corresponding to the negative step boundary are equal in magnitude and opposite in polarity; the positive step width is equal to the negative step width.

[0077] Furthermore, the control parameter calculation module calculates the quantum voltage control parameter according to the quantum voltage output request signal and the positive and negative step IV characteristic curve, including:

[0078] Obtaining a quantum voltage value to be output according to the quantum voltage output request signal;

[0079] According to the quantum voltage value to be output and the positive and negative step IV characteristic curve of each array unit, setting the bias state of each array unit;

[0080] Determining the bias current required for each array unit according to the positive and negative step IV characteristic curve;

[0081] Calculating the quantum voltage control parameter according to the bias current required by each array unit;

[0082] The quantum voltage control parameter is calculated by the following formula:

[0083] ;

[0084] (i=0,2...n-1);

[0085] Where n represents the number of array units, V bias(i) Indicates the value of the quantum voltage output corresponding to the i-th array unit, I bias(i) represents the bias current required by the i-th array unit, I DAC(i) represents the current input from the bias system to the i-th array unit, B i Indicates the bias state of the i-th array unit, and the value is 0, +1 or -1. 0 means that the array unit is in a zero bias state and there is no voltage output. +1 means that the array unit is in a positive bias state and the current direction is the same as the reference direction. -1 means that the array unit is in a negative bias state and the current direction is opposite to the reference direction. i represents the number of Josephson junctions contained in the i-th junction array unit, f0 represents the microwave frequency, K J-90 represents the Josephson constant, and R represents the resistance parameter in the bias system.

[0086] The quantum voltage output control method and device based on the Josephson array provided by the present invention have at least the following beneficial effects:

[0087] (1) By scanning the zero step and positive and negative steps of the Josephson array, more accurate positive and negative step IV characteristic curves can be obtained, and precise control and output of quantum voltage signals can be achieved, greatly improving the accuracy and stability of voltage synthesis;

[0088] (2) By scanning the array units, the array units that have lost their superconducting properties can be located. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] Figure 1 The present invention provides a flowchart of an embodiment of a quantum voltage output control method based on a Josephson array.

[0090] Figure 2 A schematic structural diagram of an embodiment of a quantum voltage synthesis system in a quantum voltage output control method based on a Josephson array provided by the present invention.

[0091] Figure 3 The present invention provides a flowchart of an embodiment of zero-step scanning in a quantum voltage output control method based on a Josephson array.

[0092] Figure 4 A schematic diagram of an embodiment of steps in the quantum voltage output control method based on the Josephson array provided by the present invention.

[0093] Figure 5 The present invention provides a flowchart of an embodiment of positive and negative step scanning in a quantum voltage output control method based on a Josephson array.

[0094] Figure 6 A schematic diagram of an embodiment of positive and negative step IV characteristic curves in the quantum voltage output control method based on the Josephson array provided by the present invention.

[0095] Figure 7 A flowchart of an embodiment of calculating quantum voltage control parameters in a quantum voltage output control method based on a Josephson array provided by the invention.

[0096] Figure 8 The present invention provides a flowchart of an embodiment of a quantum voltage output control device based on a Josephson array. DETAILED DESCRIPTION

[0097] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0098] refer to Figure 1 In some embodiments, a quantum voltage output control method based on a Josephson junction array is provided, which is applied to a quantum voltage synthesis system based on a Josephson junction array, and the method includes:

[0099] S1, receiving array scanning control signal;

[0100] S2, controlling the quantum voltage synthesis system to perform zero-step scanning according to the array scanning control signal to obtain a zero-step boundary;

[0101] S3, according to the zero step boundary, controlling the quantum voltage synthesis system to perform positive and negative step scanning to obtain positive and negative step IV characteristic curves;

[0102] S4, receiving a quantum voltage output request signal;

[0103] S5, calculating a quantum voltage control parameter according to the quantum voltage output request signal and the positive and negative step IV characteristic curve;

[0104] S6. Control the quantum voltage synthesis system to output a quantum voltage signal according to the quantum voltage control parameter.

[0105] Further, refer to Figure 2 The quantum voltage synthesis system includes a bias system 1, a cryogenic system 2, a microwave source 3 and a Josephson array 4, and the Josephson array 4 includes a plurality of array units 41.

[0106] The cryogenic system 2 provides a low temperature environment for the Josephson array 4 , the bias system 1 provides a driving bias current for the Josephson array 4 , and the microwave source 3 provides the Josephson array 4 with a required microwave frequency.

[0107] Specifically, in step S1, the execution subject of the method provided in this embodiment may be an industrial computer, which receives an array scanning control signal input by a user.

[0108] Further, refer to Figure 3 In step S2, the quantum voltage synthesis system is controlled to perform zero-step scanning according to the array scanning control signal to obtain a zero-step boundary, including:

[0109] S21, controlling the output power of the microwave source to be the lowest, and setting a first bias current scanning step length;

[0110] S22, starting from 0, controlling the bias system to increase the output bias current in sequence according to the first bias current scanning step and applying it to the array unit, detecting the output voltage of the array unit under each bias current and calculating the output voltage variation, and stopping scanning when the output voltage variation exceeds a preset threshold;

[0111] S23, judging whether the corresponding array unit loses its superconducting property according to the first variation curve of the output voltage as the bias current varies;

[0112] S24. If the array unit has not lost its superconducting property, determine a zero step boundary according to the first change curve.

[0113] Specifically, in step S21, the output power of the microwave source 3 is controlled to be the lowest, for example, -20 dBm, and the first bias current scanning step length may be 1 mA-2 mA.

[0114] Further, in step S22, starting from 0, the bias system is controlled to increase the output bias current in sequence according to the first bias current scanning step and apply it to the array unit, and the output voltage of the array unit is detected under each bias current and the output voltage change is calculated, and the output voltage change is the difference between the output voltage under the current bias current and the output voltage under the previous bias current. When the output voltage change exceeds the preset threshold, the scanning is stopped.

[0115] Further, in step S23, after stopping the scanning, a first variation curve of the output voltage changing with the bias current is obtained and it is determined whether the corresponding array unit has lost its superconducting property; specifically, if a step appears in the first variation curve of the output voltage changing with the bias current, it is determined that the corresponding array unit has not lost its superconducting property; conversely, if no step appears in the first variation curve, it indicates that the magnetic flux freezing phenomenon occurs in this section of the array unit and the superconducting property is lost.

[0116] Further, refer to Figure 4 The step is that within a certain bias current range, the output voltage remains unchanged, and at both ends of the bias current range, the corresponding output voltage jumps. Figure 4 In the figure, in the range of bias current I0 to I1, the output voltage V remains unchanged, and at bias currents I0 and I1, the output voltage V jumps, that is, steps.

[0117] Further, in step S24, if the array unit does not lose its superconducting property, that is, a step appears in the first change curve, the zero step boundary can be determined as the bias current corresponding to the starting point of the first step in the first change curve.

[0118] Further, refer to Figure 5 In step S3, according to the zero step boundary, the quantum voltage synthesis system is controlled to perform positive and negative step scanning to obtain positive and negative step IV characteristic curves, including:

[0119] S31, controlling the output power of the microwave source to be a preset value, setting a second bias current scanning step length, a third bias current scanning step length, and a fourth bias current scanning step length, wherein the second bias current scanning step length is greater than the third bias current scanning step length;

[0120] S32, taking the zero step boundary as the first scanning starting point, controlling the bias system to increase the output bias current in sequence according to the second bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current, obtaining a second variation curve of the output voltage with the bias current, and obtaining a second scanning starting point according to the second variation curve;

[0121] S33, starting from the second scanning starting point, controlling the bias system to increase the output bias current in sequence according to the third bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current, obtaining a third variation curve of the output voltage varying with the bias current, and obtaining a preset number of first current points to be calculated according to the third variation curve;

[0122] S34, starting from the second scanning starting point, controlling the bias system to sequentially reduce the output bias current according to the third bias current scanning step length and apply it to the array unit, detecting the output voltage of the array unit under each bias current, obtaining a fourth variation curve of the output voltage varying with the bias current, and obtaining a preset number of second current points to be calculated according to the fourth variation curve;

[0123] S35, calculating an average value of the second scanning starting point, a preset number of first current points to be calculated, and second current points to be calculated, as the left boundary of the positive step;

[0124] S36, taking the left boundary of the positive step as the third scanning starting point, controlling the bias system to increase the output bias current in sequence according to the fourth bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current and calculating the output voltage variation, stopping the scanning when the output voltage variation exceeds a preset threshold, obtaining a fifth variation curve of the output voltage varying with the bias current, and obtaining the positive step boundary and the positive step width according to the fifth variation curve;

[0125] S37, based on the principle of symmetry, obtaining the right boundary of the negative step, the negative step boundary and the negative step width according to the left boundary of the positive step, the positive step boundary and the positive step width;

[0126] S38. Obtain the positive and negative step IV characteristic curves of the corresponding array unit according to the left boundary of the positive step, the positive step boundary, the positive step width, the right boundary of the negative step, the negative step boundary and the negative step width.

[0127] Specifically, in step S31, the output power of the microwave source is controlled to be a preset value, for example, between 0 dBm and 6 dBm.

[0128] Further, in step S32, starting from the zero step boundary as the first scanning starting point, the bias system is controlled to increase the output bias current in sequence according to the second bias current scanning step and apply it to the array unit, the output voltage of the array unit is detected under each bias current, a second variation curve of the output voltage with the bias current is obtained, and the bias current corresponding to the starting point of the first step in the second variation curve is used as the second scanning starting point.

[0129] Further, in step S33, starting from the second scanning starting point, the bias system is controlled to increase the output bias current in sequence according to the third bias current scanning step, that is, the scanning step of the bias current is reduced, and the output voltage of the array unit is detected under each bias current to obtain a third variation curve of the output voltage changing with the bias current, and a preset number of first current points to be calculated are obtained according to the third variation curve; wherein the preset number of first current points to be calculated are the bias currents corresponding to the starting points of a preset number of steps in the third variation curve; in some embodiments, the preset number may be 3, that is, the first current point to be calculated is the bias current corresponding to the starting points of the first 3 steps in the third variation curve.

[0130] Further, in step S34, starting from the second scanning starting point, the bias system is controlled to sequentially reduce the output bias current according to the third bias current scanning step and apply it to the array unit, the output voltage of the array unit is detected under each bias current, and a fourth variation curve of the output voltage varying with the bias current is obtained, and the bias current corresponding to the starting point of a preset number of steps in the fourth variation curve is determined as the second current point to be calculated. In some embodiments, the preset number may be 3, that is, the second current point to be calculated is the bias current corresponding to the starting point of the first 3 steps in the fourth variation curve.

[0131] In step S35, the second scanning starting point, the preset number of first current points to be calculated and the second current points to be calculated are averaged to serve as the left boundary of the positive step. Figure 6 , the left boundary of the positive step is Figure 6 As shown in point A.

[0132] In step S36, the left boundary of the positive step is used as the third scanning starting point, the bias system is controlled to increase the output bias current in sequence according to the fourth bias current scanning step length and apply it to the array unit, the output voltage of the array unit is detected under each bias current and the output voltage change is calculated, and the scanning is stopped when the output voltage change exceeds a preset threshold value, and a fifth variation curve of the output voltage changing with the bias current is obtained, and the positive step boundary and the positive step width of each positive step are obtained according to the fifth variation curve; in some embodiments, the boundary and width of the first step in the fifth variation curve are taken as the positive step boundary and the positive step width, respectively, and the reference Figure 6, the positive step boundary is Figure 6 Points B and C in the figure, the positive step width is the distance between points B and C.

[0133] Further, in step S37, the bias currents corresponding to the left boundary of the positive step and the right boundary of the negative step are equal in magnitude and opposite in polarity, the bias current and output voltage corresponding to the positive step boundary and the bias current and output voltage corresponding to the negative step boundary are equal in magnitude and opposite in polarity; the positive step width is equal to the negative step width. For example, Figure 6 In the figure, point D is the right boundary of the negative step, points E and F are the boundaries of the negative step, and the width of the negative step is the distance between points E and F.

[0134] In step S38, the positive and negative step IV characteristic curves of the corresponding array unit are obtained according to the left boundary of the positive step, the positive step boundary, the positive step width, the right boundary of the negative step, the negative step boundary and the negative step width, such as Figure 6 shown.

[0135] Furthermore, in step S4, the received quantum voltage output request signal includes the quantum voltage value to be output.

[0136] Further, refer to Figure 7 In step S5, the quantum voltage control parameter is calculated according to the quantum voltage output request signal and the positive and negative step IV characteristic curve, including:

[0137] S51, obtaining a quantum voltage value to be output according to the quantum voltage output request signal;

[0138] S52, setting the bias state of each array unit according to the quantum voltage value to be output and the positive and negative step IV characteristic curve of each array unit;

[0139] S53, determining the bias current required for each array unit according to the positive and negative step IV characteristic curve;

[0140] S54, calculating the quantum voltage control parameter according to the bias current required by each array unit.

[0141] Specifically, in step S52, the bias state of each array unit is set according to the required quantum voltage value to be output and the positive and negative step IV characteristic curve of each array unit. The bias state of the array unit includes a zero bias state, a positive bias state and a negative bias state. There is no voltage output in the zero bias state. The current direction in the positive bias state is the same as the reference direction. The current direction in the negative bias state is opposite to the reference direction.

[0142] Further, in step S53, the bias current required for each array unit is determined according to the positive and negative step IV characteristic curve, that is, according to the bias state of each array unit and the required quantum voltage value to be output, the bias current corresponding to the voltage value required to be output by each array unit is obtained by searching the positive and negative step IV characteristic curve. In some embodiments, the required bias current can be the bias current corresponding to the midpoint of the positive step, negative step or zero step in the positive and negative step IV characteristic curve.

[0143] In step S54, the quantum voltage control parameter is calculated by the following formula:

[0144] ;

[0145] (i=0,2...n-1);

[0146] Where n represents the number of array units, V bias(i) Indicates the value of the quantum voltage output corresponding to the i-th array unit, I bias(i) represents the bias current required by the i-th array unit, I DAC(i) represents the current input from the bias system to the i-th array unit, B i Indicates the bias state of the i-th array unit, and the value is 0, +1 or -1. 0 means that the array unit is in a zero bias state and there is no voltage output. +1 means that the array unit is in a positive bias state and the current direction is the same as the reference direction. -1 means that the array unit is in a negative bias state and the current direction is opposite to the reference direction. i represents the number of Josephson junctions contained in the i-th junction array unit, f0 represents the microwave frequency, K J-90 represents the Josephson constant, and R represents the resistance parameter in the bias system.

[0147] Before calculating the above quantum voltage control parameters, initial values ​​need to be assigned, for example:

[0148] .

[0149] Further, in step S6, the quantum voltage synthesis system is controlled to output a required quantum voltage signal according to the quantum voltage control parameter.

[0150] Furthermore, in some embodiments, the method further comprises:

[0151] Receive array protection control signal;

[0152] According to the array protection control signal, the output power of the microwave source is controlled to be the lowest, the bias current output by the bias system is controlled to be 0, and the Josephson array is short-circuited.

[0153] When the Josephson array is not in operation, it is susceptible to electromagnetic interference from the external environment. Therefore, it is necessary to set the output of the bias system to zero, reduce the output power of the microwave source to the minimum (-20dBm), and short-circuit the output terminal of the Josephson array to prevent static electricity from damaging the array.

[0154] refer to Figure 8 In some embodiments, a quantum voltage output control device based on a Josephson array applied to the above method is also provided, comprising:

[0155] The signal receiving module 201 is used to receive the array scanning control signal;

[0156] A zero-step scanning control module 202 is used to control the quantum voltage synthesis system to perform zero-step scanning according to the array scanning control signal to obtain a zero-step boundary;

[0157] A positive and negative step scanning control module 203 is used to control the quantum voltage synthesis system to perform positive and negative step scanning according to the zero step boundary to obtain positive and negative step IV characteristic curves;

[0158] A request module 204, configured to receive a quantum voltage output request signal;

[0159] A control parameter calculation module 205, used to calculate the quantum voltage control parameter according to the quantum voltage output request signal and the positive and negative step IV characteristic curve;

[0160] The signal output control module 206 is used to control the quantum voltage synthesis system to output a quantum voltage signal according to the quantum voltage control parameter.

[0161] Furthermore, the quantum voltage synthesis system includes a bias system, a cryogenic system, a microwave source and a Josephson array, and the Josephson array includes a plurality of array units.

[0162] Furthermore, the device also includes an array protection module, which is used to:

[0163] Receive array protection control signal;

[0164] According to the array protection control signal, the output power of the microwave source is controlled to be the lowest, the bias current output by the bias system is controlled to be 0, and the Josephson array is short-circuited.

[0165] Furthermore, the zero-step scanning control module 202 controls the quantum voltage synthesis system to perform zero-step scanning according to the array scanning control signal to obtain a zero-step boundary, including:

[0166] Controlling the output power of the microwave source to be the lowest, and setting a first bias current scanning step length;

[0167] Starting from 0, controlling the bias system to increase the output bias current in sequence according to the first bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current and calculating the output voltage variation, and stopping scanning when the output voltage variation exceeds a preset threshold;

[0168] Judging whether the corresponding array unit loses its superconducting property according to a first variation curve of the output voltage as the bias current varies;

[0169] If the array unit has not lost its superconducting property, a zero step boundary is determined according to the first change curve.

[0170] Furthermore, if a step appears in the first variation curve of the output voltage with the bias current, it is determined that the corresponding array unit has not lost its superconducting property;

[0171] The step means that within a certain bias current range, the output voltage remains unchanged, and at both ends of the bias current range, the corresponding output voltage jumps;

[0172] The zero step boundary is a bias current corresponding to a starting point of the first step in the first variation curve.

[0173] Furthermore, the positive and negative step scanning control module controls the quantum voltage synthesis system to perform positive and negative step scanning according to the zero step boundary to obtain positive and negative step IV characteristic curves, including:

[0174] Controlling the output power of the microwave source to a preset value, setting a second bias current scanning step length, a third bias current scanning step length, and a fourth bias current scanning step length, wherein the second bias current scanning step length is greater than the third bias current scanning step length;

[0175] Taking the zero step boundary as the first scanning starting point, controlling the bias system to sequentially increase the output bias current according to the second bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current, obtaining a second variation curve of the output voltage with the bias current, and obtaining a second scanning starting point according to the second variation curve;

[0176] Starting from the second scanning starting point, controlling the bias system to sequentially increase the output bias current according to the third bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current, obtaining a third variation curve of the output voltage varying with the bias current, and obtaining a preset number of first current points to be calculated according to the third variation curve;

[0177] Starting from the second scanning starting point, controlling the bias system to sequentially reduce the output bias current according to the third bias current scanning step length and apply it to the array unit, detecting the output voltage of the array unit under each bias current, obtaining a fourth variation curve of the output voltage varying with the bias current, and obtaining a preset number of second current points to be calculated according to the fourth variation curve;

[0178] Calculate an average value of the second scanning starting point, a preset number of first current points to be calculated, and a second current point to be calculated, and use the average value as the left boundary of the positive step;

[0179] Taking the left boundary of the positive step as the third scanning starting point, controlling the bias system to increase the output bias current in sequence according to the fourth bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current and calculating the output voltage variation, stopping the scanning when the output voltage variation exceeds a preset threshold, obtaining a fifth variation curve of the output voltage varying with the bias current, and obtaining the positive step boundary and the positive step width according to the fifth variation curve;

[0180] Based on the principle of symmetry, the right boundary of the negative step, the negative step boundary and the negative step width are obtained according to the left boundary of the positive step, the positive step boundary and the positive step width;

[0181] The positive and negative step IV characteristic curves of the corresponding array unit are obtained according to the left boundary of the positive step, the positive step boundary, the positive step width, the right boundary of the negative step, the negative step boundary and the negative step width.

[0182] Further, the second scanning starting point is a bias current corresponding to a starting point of a first step in the second variation curve;

[0183] The preset number of first current points to be calculated are bias currents corresponding to starting points of a preset number of steps in the third variation curve;

[0184] The preset number of second current points to be calculated are bias currents corresponding to starting points of a preset number of steps in the fourth variation curve.

[0185] Furthermore, the bias currents corresponding to the left boundary of the positive step and the right boundary of the negative step are equal in magnitude and opposite in polarity, the bias current and output voltage corresponding to the positive step boundary and the bias current and output voltage corresponding to the negative step boundary are equal in magnitude and opposite in polarity; the positive step width is equal to the negative step width.

[0186] Furthermore, the control parameter calculation module 205 calculates the quantum voltage control parameter according to the quantum voltage output request signal and the positive and negative step IV characteristic curve, including:

[0187] Obtaining a quantum voltage value to be output according to the quantum voltage output request signal;

[0188] According to the quantum voltage value to be output and the positive and negative step IV characteristic curve of each array unit, setting the bias state of each array unit;

[0189] Determining the bias current required for each array unit according to the positive and negative step IV characteristic curve;

[0190] Calculating the quantum voltage control parameter according to the bias current required by each array unit;

[0191] The quantum voltage control parameter is calculated by the following formula:

[0192] ;

[0193] (i=0,2...n-1);

[0194] Where n represents the number of array units, V bias(i) Indicates the value of the quantum voltage output corresponding to the i-th array unit, I bias(i) represents the bias current required by the i-th array unit, I DAC(i) represents the current input from the bias system to the i-th array unit, B i Indicates the bias state of the i-th array unit, and the value is 0, +1 or -1. 0 means that the array unit is in a zero bias state and there is no voltage output. +1 means that the array unit is in a positive bias state and the current direction is the same as the reference direction. -1 means that the array unit is in a negative bias state and the current direction is opposite to the reference direction. i represents the number of Josephson junctions contained in the i-th junction array unit, f0 represents the microwave frequency, K J-90 represents the Josephson constant, and R represents the resistance parameter in the bias system.

[0195] The quantum voltage output control method and device based on the Josephson array provided in the above embodiment have at least the following beneficial effects:

[0196] (1) By scanning the zero step and positive and negative steps of the Josephson array, more accurate positive and negative step IV characteristic curves can be obtained, and precise control and output of quantum voltage signals can be achieved, greatly improving the accuracy and stability of voltage synthesis;

[0197] (2) By scanning the array units, the array units that have lost their superconducting properties can be located.

[0198] Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A quantum voltage output control method based on a Josephson array, characterized in that: Applied to a quantum voltage synthesis system based on a Josephson array, the method comprises: Receive array scanning control signal; Controlling the quantum voltage synthesis system to perform zero-step scanning according to the array scanning control signal to obtain a zero-step boundary; According to the zero step boundary, controlling the quantum voltage synthesis system to perform positive and negative step scanning to obtain positive and negative step IV characteristic curves; receiving a quantum voltage output request signal; Calculating a quantum voltage control parameter according to the quantum voltage output request signal and the positive and negative step IV characteristic curve; Controlling the quantum voltage synthesis system to output a quantum voltage signal according to the quantum voltage control parameter; The quantum voltage synthesis system includes a bias system, a cryogenic system, a microwave source and a Josephson array, wherein the Josephson array includes a plurality of array units; Controlling the quantum voltage synthesis system to perform zero-step scanning according to the array scanning control signal to obtain a zero-step boundary includes: Controlling the output power of the microwave source to be the lowest, and setting a first bias current scanning step length; Starting from 0, controlling the bias system to increase the output bias current in sequence according to the first bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current and calculating the output voltage variation, and stopping scanning when the output voltage variation exceeds a preset threshold; Judging whether the corresponding array unit loses its superconducting property according to a first variation curve of the output voltage as the bias current varies; If the array unit has not lost its superconducting property, a zero step boundary is determined according to the first change curve.

2. The method according to claim 1, characterized in that The method further comprises: Receive array protection control signal; According to the array protection control signal, the output power of the microwave source is controlled to be the lowest, the bias current output by the bias system is controlled to be 0, and the Josephson array is short-circuited.

3. The method according to claim 1, characterized in that If a step appears in the first variation curve of the output voltage with the bias current, it is determined that the corresponding array unit has not lost its superconducting property; The step means that within a certain bias current range, the output voltage remains unchanged, and at both ends of the bias current range, the corresponding output voltage jumps; The zero step boundary is a bias current corresponding to a starting point of the first step in the first variation curve.

4. The method according to claim 1, characterized in that According to the zero step boundary, the quantum voltage synthesis system is controlled to perform positive and negative step scanning to obtain positive and negative step IV characteristic curves, including: Controlling the output power of the microwave source to a preset value, setting a second bias current scanning step length, a third bias current scanning step length, and a fourth bias current scanning step length, wherein the second bias current scanning step length is greater than the third bias current scanning step length; Taking the zero step boundary as the first scanning starting point, controlling the bias system to sequentially increase the output bias current according to the second bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current, obtaining a second variation curve of the output voltage with the bias current, and obtaining a second scanning starting point according to the second variation curve; Starting from the second scanning starting point, controlling the bias system to sequentially increase the output bias current according to the third bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current, obtaining a third variation curve of the output voltage varying with the bias current, and obtaining a preset number of first current points to be calculated according to the third variation curve; Starting from the second scanning starting point, controlling the bias system to sequentially reduce the output bias current according to the third bias current scanning step length and apply it to the array unit, detecting the output voltage of the array unit under each bias current, obtaining a fourth variation curve of the output voltage varying with the bias current, and obtaining a preset number of second current points to be calculated according to the fourth variation curve; Calculate an average value of the second scanning starting point, a preset number of first current points to be calculated, and a second current point to be calculated, and use the average value as the left boundary of the positive step; Taking the left boundary of the positive step as the third scanning starting point, controlling the bias system to increase the output bias current in sequence according to the fourth bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current and calculating the output voltage variation, stopping the scanning when the output voltage variation exceeds a preset threshold, obtaining a fifth variation curve of the output voltage varying with the bias current, and obtaining the positive step boundary and the positive step width according to the fifth variation curve; Based on the principle of symmetry, the right boundary of the negative step, the negative step boundary and the negative step width are obtained according to the left boundary of the positive step, the positive step boundary and the positive step width; The positive and negative step IV characteristic curves of the corresponding array unit are obtained according to the left boundary of the positive step, the positive step boundary, the positive step width, the right boundary of the negative step, the negative step boundary and the negative step width.

5. The method according to claim 4, characterized in that The second scanning starting point is a bias current corresponding to the starting point of the first step in the second variation curve; The preset number of first current points to be calculated are bias currents corresponding to starting points of a preset number of steps in the third variation curve; The preset number of second current points to be calculated are bias currents corresponding to starting points of a preset number of steps in the fourth variation curve.

6. The method according to claim 4, characterized in that The bias currents corresponding to the left boundary of the positive step and the right boundary of the negative step are equal in magnitude and opposite in polarity, and the bias current and output voltage corresponding to the positive step boundary and the bias current and output voltage corresponding to the negative step boundary are equal in magnitude and opposite in polarity; The positive step width is equal to the negative step width.

7. The method according to claim 1, characterized in that Calculating quantum voltage control parameters according to the quantum voltage output request signal and the positive and negative step IV characteristic curves includes: Obtaining a quantum voltage value to be output according to the quantum voltage output request signal; According to the quantum voltage value to be output and the positive and negative step IV characteristic curve of each array unit, setting the bias state of each array unit; Determining the bias current required for each array unit according to the positive and negative step IV characteristic curve; Calculating the quantum voltage control parameter according to the bias current required by each array unit; The quantum voltage control parameter is calculated by the following formula: ； Where n represents the number of array units, V bias(i) Indicates the value of the quantum voltage output corresponding to the i-th array unit, I bias(i) represents the bias current required by the i-th array unit, I DAC(i) represents the current input from the bias system to the i-th array unit, Bi represents the bias state of the i-th array unit, and its value is 0, +1 or -1. 0 represents that the array unit is in a zero bias state and has no voltage output, +1 represents that the array unit is in a positive bias state and the current direction is the same as the reference direction, -1 represents that the array unit is in a negative bias state and the current direction is opposite to the reference direction, Mi represents the number of Josephson junctions contained in the i-th array unit, f0 represents the microwave frequency, and K J-90 represents the Josephson constant, and R represents the resistance parameter in the bias system.

8. A quantum voltage output control device based on a Josephson array applied to the method according to any one of claims 1 to 7, characterized in that: include: A signal receiving module, used for receiving array scanning control signals; A zero-step scanning control module, used to control the quantum voltage synthesis system to perform zero-step scanning according to the array scanning control signal to obtain a zero-step boundary; A positive and negative step scanning control module, used to control the quantum voltage synthesis system to perform positive and negative step scanning according to the zero step boundary to obtain positive and negative step IV characteristic curves; A request module, used for receiving a quantum voltage output request signal; A control parameter calculation module, used to calculate the quantum voltage control parameter according to the quantum voltage output request signal and the positive and negative step IV characteristic curve; A signal output control module, used to control the quantum voltage synthesis system to output a quantum voltage signal according to the quantum voltage control parameter; A Josephson array, wherein the Josephson array comprises a plurality of array units; The zero-step scanning control module controls the quantum voltage synthesis system to perform zero-step scanning according to the array scanning control signal to obtain a zero-step boundary, including: Controlling the output power of the microwave source to be the lowest, and setting a first bias current scanning step length; Starting from 0, controlling the bias system to increase the output bias current in sequence according to the first bias current scanning step length and applying it to the array unit, detecting the output voltage of the array unit under each bias current and calculating the output voltage variation, and stopping scanning when the output voltage variation exceeds a preset threshold; Judging whether the corresponding array unit loses its superconducting property according to a first variation curve of the output voltage as the bias current varies; If the array unit has not lost its superconducting property, a zero step boundary is determined according to the first change curve.

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