Multi-channel Superconducting Quantum Interference Device Measurement System and Non-destructive Crosstalk Calibration Method

Abstract

The present invention provides a multi-channel superconducting quantum interference device measurement system and a non-destructive crosstalk calibration method. 1) Adjust the multi-channel superconducting quantum interference device measurement system to an external feedback mode, respectively calibrate the channel crosstalk coefficients caused by the pickup coil and the external feedback coil, and eliminate the crosstalk of the external feedback mode by means of physical deduction based on the channel crosstalk coefficient caused by the external feedback coil; 2) Adjust the multi-channel superconducting quantum interference device measurement system to an internal feedback mode, calibrate the channel crosstalk coefficient caused by the internal feedback coil, and eliminate the crosstalk of the internal feedback mode by means of physical deduction based on the channel crosstalk coefficients caused by the pickup coil and the internal feedback coil. The present invention realizes non-destructive calibration and elimination of crosstalk in a multi-channel SQUID measurement system integrating a Pickup coil, and has high precision; the present invention is simple to implement, easy to operate, and suitable for applications in high-precision magnetic measurement fields based on SQUID such as super navigation magnetism.

Description

Technical Field

[0001] The present invention relates to the field of magnetic field detection, and in particular to a multi-channel superconducting quantum interference device measurement system and a non-destructive crosstalk calibration method. Background Art

[0002] A superconducting quantum interference device (SQUID) is a flux-voltage converter based on a Josephson junction. The superconducting magnetic sensor composed of it is currently the most sensitive magnetic sensor known for practical use. At present, superconducting magnetic measurement systems with SQUIDs as the core components have been widely used in the field of detecting extremely weak magnetic fields such as biomagnetism, geophysics, and low-field nuclear magnetic resonance. However, when the physical space of the detectors is limited in a magnetic measurement system composed of multiple SQUIDs, there will be a problem of channel crosstalk, which will greatly affect the measurement accuracy of the system.

[0003] When a superconducting quantum interference device is used as a magnetic sensor, it requires the cooperation of a readout circuit. That is, the SQUID needs to be linearized through a readout circuit based on a flux lock loop (FLL) after noise matching to achieve the purpose of practical use. The working principle of the SQUID readout circuit based on the FLL working mode is to cancel the change of the external magnetic field through the feedback coil of the SQUID itself, so that its working point always remains at a certain fixed point on the I–Φ (V–Φ) curve. During this process, because of its active feedback, crosstalk will be introduced when multiple SQUID measurement channels work synchronously.

[0004] To measure the magnetic field gradient or improve the measurement resolution of the SQUID, a Pickup coil and an Input coil made of superconducting materials need to be introduced at the front end of the SQUID. The Pickup coil is used to collect the measured signal, and the Input coil is used to couple with the Loop (superconducting loop) of the SQUID, that is, to transmit the measured signal collected by the Pickup coil to the SQUID. When the external magnetic field changes, the Pickup coil and the Input coil working in the superconducting state will couple out corresponding changing currents, which will also introduce crosstalk when multiple SQUID measurement channels work synchronously, and even become the main source of crosstalk. It should be noted that according to the working principle of the SQUID readout circuit, the mode of applying the Feedback coil to the Pickup coil is called external feedback, and the mode of applying the Feedback coil to the SQUID Loop is called internal feedback.

[0005] Although the problem of crosstalk calibration of some SQUID measurement components can be solved in the prior art, it is helpless for a multi-channel SQUID measurement component integrating a Pickup coil and an Input coil. Because the Pickup coil is large in size, especially in a gradiometer, a substrate material with excellent heat dissipation performance such as sapphire is usually used to improve its balance index, resulting in the inability to ensure that the SQUID's heating coil is used to make it enter the quench state, so that the influence of the current in the Pickup coil and the Input coil on crosstalk cannot be eliminated by artificially closing the crosstalk channel.

[0006] Currently, the method for calibrating the crosstalk of a multi-channel superconducting quantum interference device measurement system with a Pickup coil and an Input coil is basically to place a micro excitation coil under the crosstalk channel, so that the crosstalk channel can receive its signal with a high signal-to-noise ratio, while the signal can be ignored for the crosstalked channel. Thus, the relevant crosstalk coefficient can be obtained according to the output changes of the crosstalked channel and the crosstalk channel. However, in the actual use process, it is found that this calibration method has the following disadvantages: First, it is impossible to accurately evaluate whether the crosstalked channel can ignore the signal generated by the micro excitation coil, thus affecting the accuracy of crosstalk calibration; Second, the SQUID needs to be equipped with a cryostat - Dewar to work normally. For a multi-channel SQUID measurement system, due to space limitations, it is not always possible to find a suitable measurement point for the micro excitation coil, so it needs to be embedded near the multi-channel SQUID measurement component working at a low temperature state, and then the relevant test system needs to be modified, and the calibration workload is greatly increased.

[0007] In summary, when the space is limited, the existing crosstalk calibration method for a multi-channel SQUID measurement system integrating a Pickup coil not only has problems such as a large calibration workload, but also has problems such as inconvenient system modification and even damage to the system integrity. And the crosstalk calibration and elimination of the SQUID measurement system are crucial for the strategically significant airborne superconducting magnetic measurement device, thus leading to the concept of this application. Summary of the Invention

[0008] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a multi-channel superconducting quantum interference device measurement system and a non-destructive crosstalk calibration method, which are used to solve the problems such as large calibration workload, inconvenient system modification, and damage to system integrity in the prior art for a multi-channel SQUID measurement system integrating a Pickup coil.

[0009] To achieve the above purpose and other related purposes, the present invention provides a non-destructive crosstalk calibration method for a multi-channel superconducting quantum interference device measurement system. The non-destructive crosstalk calibration method at least includes:

[0010] 1) Adjust the multi-channel superconducting quantum interference device (SQUID) measurement system to the external feedback mode, calibrate the channel crosstalk coefficients caused by the pickup coil and the external feedback coil in the multi-channel SQUID measurement system respectively, and eliminate the crosstalk of the external feedback mode by physical deduction based on the channel crosstalk coefficient caused by the external feedback coil.

[0011] Optionally, the method for calibrating the channel crosstalk coefficients caused by the pickup coil and the external feedback coil in step 1) includes:

[0012] 111) Control the crosstalked channel to be in the normal locked state, control the crosstalking channel to be in the no-feedback mode and adjust the crosstalking channel not to respond to the external magnetic field and the output to tend to zero; simulate the actual measured magnetic field, and generate a first constant magnetic field in the crosstalked channel and the crosstalking channel, and obtain the first voltage output by the crosstalked channel;

[0013] 112) Cancel the first constant magnetic field, control the crosstalking channel to be in the normal locked state, simulate the actual measured magnetic field again, and generate the first constant magnetic field in the crosstalked channel and the crosstalking channel, and obtain the second voltage output by the crosstalked channel; and obtain the third voltage output by the crosstalking channel in the feedback mode;

[0014] 113) Control the crosstalking channel to be in the normal locked state, adjust the current of the external feedback coil, and obtain the fourth voltage output by the crosstalked channel; and obtain the fifth voltage output by the crosstalking channel in the normal locked state under the first constant magnetic field;

[0015] 114) Calculate the channel crosstalk coefficient caused by the pickup coil between the crosstalked channel and the crosstalking channel based on the first voltage, the second voltage, the third voltage and the first constant magnetic field, and calculate the channel crosstalk coefficient caused by the external feedback coil between the crosstalked channel and the crosstalking channel based on the second voltage, the fourth voltage, the third voltage and the fifth voltage;

[0016] 115) Select different crosstalking channels and crosstalked channels to execute the above steps 111) to 114) to obtain the channel crosstalk coefficient matrix of the multi-channel SQUID measurement system in the external feedback mode.

[0017] More optionally, the method for adjusting the current of the external feedback coil in step 113) includes: adjusting the first constant magnetic field so that there is a fractional flux quantum in the magnetic flux corresponding to the SQUID operating point of the crosstalking channel.

[0018] More optionally, the method for adjusting the current of the external feedback coil in step 113) includes: after adjusting the operating parameters of the crosstalk channel to make the crosstalk channel in a normal locked state, adjusting the offset voltage of the crosstalk channel to change the current of the external feedback coil.

[0019] More optionally, the method for adjusting the current of the external feedback coil in step 113) includes: adjusting the operating parameters of the crosstalk channel or changing the external electromagnetic environment to cause a flux jump within the range of the crosstalk channel, while the crosstalked channel does not have a flux jump.

[0020] More optionally, the channel crosstalk coefficient caused by the external feedback coil satisfies:

[0021]

[0022] where k ij is the channel crosstalk coefficient caused by the external feedback coil between the crosstalked channel i and the crosstalk channel j in the external feedback mode; V i out2 is the second voltage output by the crosstalked channel i; V i out4 is the fourth voltage output by the crosstalked channel i; is the third voltage output by the crosstalk channel j; is the fifth voltage output by the crosstalk channel j.

[0023] More optionally, the channel crosstalk coefficient caused by the pick-up coil satisfies:

[0024]

[0025] where is the channel crosstalk coefficient caused by the pick-up coil between the crosstalked channel i and the crosstalk channel j; is the magnitude of the first constant magnetic field; V i out1 is the first voltage output by the crosstalked channel i; V i out2 is the second voltage output by the crosstalked channel i; is the third voltage output by the crosstalk channel j.

[0026] More optionally, the output after crosstalk cancellation satisfies:

[0027]

[0028] where V i b is the output after crosstalk cancellation of channel i; V jis the output of the crosstalk channel j; i = 1, 2... n; j = 1, 2... n.

[0029] Optionally, the lossless crosstalk calibration method further includes:

[0030] 2) Adjust the multi-channel superconducting quantum interference device measurement system to the internal feedback mode, calibrate the channel crosstalk coefficient caused by the internal feedback coil in the multi-channel superconducting quantum interference device measurement system, and eliminate the crosstalk of the internal feedback mode by physical deduction based on the channel crosstalk coefficient caused by the pickup coil and the internal feedback coil.

[0031] More optionally, the method for calibrating the channel crosstalk coefficient caused by the internal feedback coil in step 2) includes:

[0032] 21) Control the crosstalked channel and the crosstalk channel to be in the normal locked state, simulate the actual measured magnetic field, and generate a second constant magnetic field in the crosstalked channel and the crosstalk channel, and obtain the sixth voltage output by the crosstalked channel and the seventh voltage output by the crosstalk channel;

[0033] 22) Reset the crosstalk channel, and obtain the eighth voltage output by the crosstalked channel and the ninth voltage output by the crosstalk channel;

[0034] 23) Calculate the channel crosstalk coefficient caused by the internal feedback coil between the crosstalked channel and the crosstalk channel based on the sixth voltage, the seventh voltage, the eighth voltage, and the ninth voltage;

[0035] 24) Select different crosstalk channels and crosstalked channels to execute the above steps 21) to 23) to obtain the channel crosstalk coefficient matrix of the multi-channel superconducting quantum interference device measurement system in the internal feedback mode.

[0036] More optionally, the channel crosstalk coefficient caused by the internal feedback coil satisfies:

[0037]

[0038] where m ij is the channel crosstalk coefficient caused by the internal feedback coil between the crosstalked channel i and the crosstalk channel j in the internal feedback mode; V i outA1 is the sixth voltage output by the crosstalked channel i; V i outA2 is the eighth voltage output by the crosstalked channel i; is the seventh voltage output by the crosstalk channel j; is the ninth voltage output by the crosstalk channel j.

[0039] More optionally, the output after crosstalk elimination satisfies:

[0040]

[0041] Among them, V i b is the output after crosstalk cancellation for channel i; V j is the output of the crosstalk channel j; is the channel crosstalk coefficient caused by the pickup coil between the crosstalked channel i and the crosstalk channel j; is the magnitude of the second constant magnetic field loaded on channel i; i = 1, 2... n; j = 1, 2... n.

[0042] Optionally, the fluidity or volatility of liquid helium is used to replace heating to quench the pickup coil, so as to achieve lossless crosstalk calibration on the basis of the traditional method. When using the volatility of liquid helium to replace heating to quench the pickup coil, the multi-channel superconducting quantum interference device needs to meet the requirement of quenching in sequence as the liquid helium level drops.

[0043] Optionally, the method for calibrating the channel crosstalk coefficient caused by the feedback coil includes:

[0044] 121) By tilting the dewar to control the fluidity of liquid helium or using the volatility of liquid helium, control the crosstalked channel to be in the superconducting state, while the crosstalk channel is in the non-superconducting state;

[0045] 122) Control the crosstalked channel to be in the normal locked state, control the crosstalk channel to be in the no-feedback mode and adjust the crosstalk channel not to respond to the external magnetic field and the output tends to zero value, and obtain the tenth voltage output by the crosstalked channel;

[0046] 123) Load a crosstalk test signal from the output port of the crosstalk channel, and obtain the eleventh voltage output by the crosstalked channel and the twelfth voltage loaded on the crosstalk channel;

[0047] 124) Calculate the channel crosstalk coefficient caused by the feedback coil based on the tenth voltage, the eleventh voltage and the twelfth voltage, satisfying:

[0048]

[0049] Among them, k ij is the channel crosstalk coefficient caused by the feedback coil between the crosstalked channel i and the crosstalk channel j in the corresponding feedback mode; V i out10 is the tenth voltage output by the crosstalked channel i; V i out11 is the eleventh voltage output by the crosstalked channel i; is the twelfth voltage loaded on the crosstalk channel j.

[0050] Optionally, the method for calibrating the channel crosstalk coefficient caused by the feedback coil includes:

[0051] 131) Utilize the fluidity or volatility of liquid helium to control both the crosstalked channel and the crosstalking channel to be in the superconducting state;

[0052] 132) Control the crosstalked channel to be in the normal locked state, control the crosstalking channel to be in the no-feedback mode, adjust the crosstalking channel not to respond to the external magnetic field and the output to tend to zero, and generate a third constant magnetic field in the crosstalked channel and the crosstalking channel, and obtain the fifteenth voltage output by the crosstalked channel;

[0053] 133) Utilize the fluidity or volatility of liquid helium to control the crosstalked channel to be in the superconducting state while the crosstalking channel is in the non-superconducting state;

[0054] 134) Generate the third constant magnetic field in the crosstalked channel and the crosstalking channel, and obtain the sixteenth voltage output by the crosstalked channel;

[0055] 135) Calculate the channel crosstalk coefficient caused by the pickup coil based on the fifteenth voltage and the sixteenth voltage, satisfying:

[0056]

[0057] wherein, is the channel crosstalk coefficient caused by the pickup coil between the crosstalked channel i and the crosstalking channel j; is the magnitude of the third constant magnetic field; V i out15 is the fifteenth voltage output by the crosstalked channel i; V i out16 is the sixteenth voltage output by the crosstalked channel i.

[0058] To achieve the above object and other related objects, the present invention provides a multi-channel superconducting quantum interference device measurement system to implement the above non-destructive crosstalk calibration method. The multi-channel superconducting quantum interference device measurement system at least includes:

[0059] SQUID measurement module, high-performance coil, power signal source, measurement and control component, and crosstalk calibration module;

[0060] The power signal source provides an excitation signal;

[0061] The high-performance coil is connected to the power signal source and is used to generate a magnetic field;

[0062] The SQUID measurement module is arranged in the working area of the high-performance coil and responds to the magnetic field generated by the high-performance coil;

[0063] The measurement and control component is connected to the SQUID measurement module, sets the working parameters of the SQUID measurement module, and acquires the data of the SQUID measurement module.

[0064] The crosstalk calibration module is connected to the output end of the measurement and control component, and calculates the crosstalk coefficients between channels based on the output signal of the measurement and control component.

[0065] Optionally, the SQUID measurement module includes a SQUID measurement component and a SQUID readout circuit. The SQUID readout circuit is connected to the SQUID measurement component to read the output data of the SQUID measurement component.

[0066] More optionally, when the multi-channel superconducting quantum interference device measurement system is used to eliminate crosstalk in the external feedback mode, the SQUID measurement component includes a pickup coil, an input coil, and an external feedback coil; when the multi-channel superconducting quantum interference device measurement system is used to eliminate crosstalk in the internal feedback mode, the SQUID measurement component includes a pickup coil, an input coil, an external feedback coil, and an internal feedback coil.

[0067] Optionally, the multi-channel superconducting quantum interference device measurement system further includes a magnetic shielding chamber, and the high-performance coil is placed in the magnetic shielding chamber.

[0068] As described above, the multi-channel superconducting quantum interference device measurement system and the non-destructive crosstalk calibration method of the present invention have the following beneficial effects:

[0069] The multi-channel superconducting quantum interference device measurement system and the non-destructive crosstalk calibration method of the present invention can not only improve the accuracy of crosstalk calibration while realizing crosstalk calibration and elimination of a multi-channel SQUID measurement system integrating a pickup coil, but also realize crosstalk calibration without damage without changing the multi-channel SQUID measurement system. In addition, the calibration constructed by the present invention is simple to implement and easy to operate, and is very suitable for application in high-precision magnetic measurement fields based on SQUIDs such as super navigation magnetism. Description of the Drawings

[0070] Figure 1 It shows a schematic structural diagram of the multi-channel superconducting quantum interference device measurement system of the present invention.

[0071] Figure 2 It shows a schematic flow diagram of the non-destructive crosstalk calibration method of the present invention.

[0072] Figure 3 It shows a schematic flow diagram of crosstalk calibration in the external feedback mode of the present invention.

[0073] Explanation of Component Labels

[0074] 1 Multi-channel Superconducting Quantum Interference Device Measurement System

[0075] 11 Power Signal Source

[0076] 111 Signal Source

[0077] 112 Power Amplifier

[0078] 12 High-performance Coil

[0079] 13 SQUID Measurement Module

[0080] 131 SQUID Measurement Component

[0081] 132 SQUID Readout Circuit

[0082] 14 Measurement and Control Component

[0083] 15 Crosstalk Calibration Module

[0084] 16 Magnetic Shielding Room Detailed Implementation Manner

[0085] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0086] Please refer to Figures 1 to 3 . It should be noted that the diagrams provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the diagrams, rather than being drawn according to the number, shape, and size of the components in actual implementation. The types, quantities, and proportions of the components in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0087] Embodiment 1

[0088] As Figure 1 shown, this embodiment provides a multi-channel superconducting quantum interference device measurement system 1, and the multi-channel superconducting quantum interference device measurement system 1 at least includes:

[0089] Power signal source 11, high-performance coil 12, SQUID measurement module 13, measurement and control component 14, and crosstalk calibration module 15.

[0090] As Figure 1 shown, the power signal source 11 provides an excitation signal.

[0091] Specifically, in this embodiment, the power signal source 11 includes a signal source 111 and a power amplifier 112. The signal source 111 generates an excitation signal and supplies it to the measurement control module 14. The power amplifier 112 is connected to the output end of the signal source 111, amplifies the excitation signal and supplies it to the high-performance coil 12. In actual use, the power signal source 11 includes, but is not limited to, a combination of a battery and a voltage regulator. Any device that can generate an excitation signal is applicable to the present invention and will not be elaborated here one by one.

[0092] As Figure 1 shown, the high-performance coil 12 is connected to the power signal source 11 and is used to generate a magnetic field.

[0093] Specifically, the high-performance coil 12 simulates a constant magnetic field with the same magnitude as or equal to the actual magnetic field strength to be measured based on the excitation signal. As an example, if a magnetometer is used in the SQUID measurement module 13, the high-performance coil 12 is selected as a uniform magnetic field coil, including but not limited to a Helmholtz coil. As another example, if a gradiometer is used in the SQUID measurement module 13, the high-performance coil 12 is selected as a linear gradient coil, including but not limited to a Maxwell coil.

[0094] As Figure 1 shown, the SQUID measurement module 13 is arranged in the working area of the high-performance coil 12 and responds to the magnetic field generated by the high-performance coil 12.

[0095] Specifically, the SQUID measurement module 13 includes a SQUID measurement component 131 and a SQUID readout circuit 132, and the number of channels is not less than 2. The SQUID measurement component 131 is used to measure the magnetic field, including but not limited to a pickup coil, an input coil, an outer feedback coil and an inner feedback coil; when the multi-channel superconducting quantum interference device measurement system 1 is used to eliminate the crosstalk of the outer feedback mode, the SQUID measurement component includes a pickup coil, an input coil and an outer feedback coil; when the multi-channel superconducting quantum interference device measurement system 1 is used to eliminate the crosstalk of the inner feedback mode, the SQUID measurement component includes a pickup coil, an input coil, an outer feedback coil and an inner feedback coil. The SQUID readout circuit 132 is connected to the output end of the SQUID measurement component 131 and reads the measurement result of the SQUID measurement component 131. Any structure of the SQUID measurement component and the SQUID readout circuit that can realize magnetic field detection and signal readout is applicable to the present invention and will not be elaborated here one by one.

[0096] As Figure 1As shown, the measurement and control component 14 is connected to the SQUID measurement module 13 to set the operating parameters of the SQUID measurement module 13 and collect the data of the SQUID measurement module 13.

[0097] Specifically, as an example, the measurement and control component 14 is implemented by the measurement and control component of the SQUID test system itself. The measurement and control component is a module for measuring and controlling the SQUID component, including but not limited to a display, a configuration unit, a filter, and an analog-to-digital conversion unit. The measurement and control component measures the output of the sine magnetic field applied to the three-dimensional Helmholtz coil corresponding to the crosstalk channel or the crosstalked channel based on a weak signal detection method including but not limited to digital two-phase lock-in amplification technology. Any structure that can cooperate with the SQUID measurement module 13 is applicable to the present invention and will not be elaborated here one by one. As another example, the measurement and control component 14 is implemented by a two-phase lock-in amplifier, and the measurement and control component 14 is connected to the output end of the SQUID readout circuit 132. In actual use, any detection device that can detect weak signals is applicable to the present invention and is not limited to this embodiment.

[0098] As Figure 1 shown, the crosstalk calibration module 15 is connected to the output end of the measurement and control component 14, and calculates the crosstalk coefficients between the channels based on the output signal of the measurement and control component 14.

[0099] Specifically, in this embodiment, the crosstalk calibration module 15 is implemented by a digital processor. In actual use, any device that can calculate the crosstalk coefficients between the channels in the SQUID measurement module 13 based on the output signal of the measurement and control component 14 is applicable to the present invention.

[0100] As another implementation manner of the present invention, the multi-channel superconducting quantum interference device measurement system 1 further includes a magnetic shielding chamber 16, and the high-performance coil 12 is placed in the magnetic shielding chamber 16 to achieve a low-noise background magnetic field. When the interference of the background magnetic field is within an acceptable range, the magnetic shielding chamber 16 can be omitted.

[0101] Embodiment 2

[0102] As Figure 2 and Figure 3 shown, this embodiment provides a non-destructive crosstalk calibration method for a multi-channel superconducting quantum interference device measurement system. The non-destructive crosstalk calibration method at least includes:

[0103] 1) The multi-channel superconducting quantum interference instrument measurement system 1 is adjusted to the external feedback mode, the channel crosstalk coefficients caused by the pickup coil and the external feedback coil in the multi-channel superconducting quantum interference instrument measurement system 1 are calibrated respectively, and the crosstalk of the external feedback mode is eliminated by physical deduction based on the channel crosstalk coefficient caused by the external feedback coil.

[0104] like Figure 3 As shown, first, a multi-channel SQUID measurement system 1 compatible with internal and external feedback is provided (in this embodiment, for simplicity of description, a multi-channel SQUID measurement system that takes into account both internal and external feedback modes is adopted. In actual use, a multi-channel SQUID measurement system with only external feedback mode can be used to achieve non-destructive calibration of crosstalk between the external feedback coil and the pickup coil, which is not limited to this embodiment). It is set to external feedback mode. In this embodiment, the multi-channel SQUID measurement system 1 is implemented using the multi-channel SQUID measurement system of Example 1, which is not described in detail here. In actual use, any system that can implement this method is applicable, which is not limited to this embodiment. Then, the SQUID measurement module 13 is placed in the working area of the high-performance coil 12 (as another example, the high-performance coil 12 is pre-placed in the magnetic shielding room 16 to provide a low-noise background magnetic field) and calibration begins. It should be noted that in this example, in the external feedback mode, the pickup coil and the external feedback coil are mutually inductive, and the feedback signal is sensed by the pickup coil and fed back to the readout circuit.

[0105] The method for calibrating the channel crosstalk coefficient caused by the pickup coil and the external feedback coil further includes:

[0106] 111) Controlling the crosstalk channel to be in a normal locked state, controlling the crosstalk channel to be in a no-feedback mode and adjusting the crosstalk channel to not respond to the external magnetic field and the output tends to zero; simulating the actual measured magnetic field, and generating a first constant magnetic field in the crosstalk channel and the crosstalk channel, and obtaining a first voltage output by the crosstalk channel.

[0107] Specifically, in this embodiment, the measurement and control component 14 adjusts, via the SQUID readout circuit 132, the operating parameters of the crosstalk channel i (i.e., the crosstalk channel to be calibrated) in the SQUID measurement component 131, so that the crosstalk channel i is in a normal locked (Lock) state; then, the measurement and control component 14 adjusts, via the SQUID readout circuit 132, the operating parameters of the crosstalk channel j in the SQUID measurement component 131, so that the crosstalk channel j operates in a no-feedback state (Tune), and adjusts the bias current Bias and the offset voltage offset of the crosstalk channel j to turn off this crosstalk channel j. If necessary, its output terminal can also be grounded, so that the crosstalk channel j does not respond to the external magnetic field and its output tends to zero (at this time, the crosstalked channel outputs the thirteenth voltage). Meanwhile, when the crosstalk channel j is in the no-feedback mode, the crosstalk channel outputs the fourteenth voltage; it should be noted that the fourteenth voltage can be obtained at any time when the crosstalk channel j is in the no-feedback mode. As an example, it can be obtained before or after adjusting the bias current Bias and the offset voltage offset of the crosstalk channel j, which will not be elaborated here one by one.

[0108] Specifically, in this embodiment, the high-performance coil 12 is used to simulate the actual magnetic field to be measured, and the high-performance coil 12 generates a first constant magnetic field equal to or of the same order of magnitude as the actual magnetic field to be measured in the crosstalk channel i and the crosstalk channel j, and measures and records the first voltage V i out1 , V i out1 output by the crosstalked channel i after loading the first constant magnetic field and when the crosstalk channel is in the Tune state.

[0109] 112) Cancel the first constant magnetic field, control the crosstalk channel to be in the normal locked state, simulate the actual magnetic field to be measured again, and generate the first constant magnetic field in the crosstalked channel and the crosstalk channel, and obtain the second voltage V i out2 output by the crosstalked channel; and obtain the third voltage V j out3 output by the crosstalk channel in the feedback mode.

[0110] 113) Control the crosstalk channel to be in the normal locked state, adjust the current of the external feedback coil, and obtain the fourth voltage output by the crosstalked channel; and obtain the fifth voltage output by the crosstalk channel in the normal locked state under the first constant magnetic field.

[0111] Specifically, as an example, the method for adjusting the current of the external feedback coil includes: adjusting the constant magnetic field so that there is a fractional flux quantum in the magnetic flux corresponding to the SQUID operating point of the crosstalk channel. As another example, after adjusting the operating parameters of the crosstalk channel j to make the crosstalk channel j in a normal locked state, then adjusting the offset voltage of the crosstalk channel j to change the current of the external feedback coil. As yet another example, adjusting the operating parameters of the crosstalk channel or changing the external electromagnetic environment to cause a flux jump within the range of the crosstalk channel while the crosstalked channel does not exhibit a flux jump, so as to change the current of the external feedback coil. In actual use, any method that can change the current of the external feedback coil is applicable to the present invention and is not limited to this embodiment.

[0112] Specifically, through the measurement and control component 14, the operating parameters of the crosstalk channel j in the SQUID measurement component 131 are adjusted via the SQUID readout circuit 132 to the current of the external feedback coil when the crosstalk channel j is in a normal locked (Lock) state (as an example, increasing the current of the external feedback coil). After it stably operates, measure and record the fourth voltage V i out4 , V i out4 output by the crosstalked channel i after loading the first constant magnetic field and when the crosstalk channel j is in the Lock state.

[0113] Specifically, at the same time, when the crosstalk channel j is in a normal locked state under the first constant magnetic field, obtain the fifth voltage output by the crosstalk channel It should be noted that the fifth voltage can be obtained at any time after loading the first constant magnetic field and when the crosstalk channel j is in the Lock state. As an example, it can be before and after adjusting the current of the external feedback coil. Details are not elaborated here one by one.

[0114] 114) Calculate the channel crosstalk coefficient caused by the pickup coil between the crosstalked channel and the crosstalk channel based on the first voltage, the second voltage, the third voltage, and the first constant magnetic field, and calculate the channel crosstalk coefficient caused by the external feedback coil between the crosstalked channel and the crosstalk channel based on the second voltage, the fourth voltage, the third voltage, and the fifth voltage.

[0115] Specifically, the channel crosstalk coefficient caused by the external feedback coil satisfies:

[0116]

[0117] where k ijis the channel crosstalk coefficient caused by the external feedback coil between the crosstalked channel i and the crosstalk channel j in the external feedback mode; V i out2 is the second voltage output by the crosstalked channel i; V i out4 is the fourth voltage output by the crosstalked channel i; is the third voltage output by the crosstalk channel j; is the fifth voltage output by the crosstalk channel j.

[0118] Specifically, the channel crosstalk coefficient caused by the pickup coil satisfies:

[0119]

[0120] wherein, is the channel crosstalk coefficient caused by the pickup coil between the crosstalked channel i and the crosstalk channel j; is the magnitude of the first constant magnetic field; V i out1 is the first voltage output by the crosstalked channel i; V i out2 is the second voltage output by the crosstalked channel i; is the third voltage output by the crosstalk channel j.

[0121] 115) Select different crosstalk channels and crosstalked channels to execute the above steps 111) to 114) to obtain the channel crosstalk coefficient matrix of the multi-channel superconducting quantum interference measurement system in the external feedback mode.

[0122] Specifically, the channel crosstalk coefficient matrix of the multi-channel superconducting quantum interference measurement system is obtained by sequentially selecting different crosstalk channels j and crosstalked channels i in a traversal manner, and then the crosstalk of the crosstalked channel is eliminated in a physical deduction manner according to the output value of the crosstalk channel j in the actual working state. It should be noted that in the SQUID measurement system with an integrated Pickup coil operating in the external feedback mode, the internal current of the Pickup coil remains constant without losing lock, that is, during normal operation, the crosstalk introduced by the Pickup coil can be ignored, and the output after crosstalk elimination satisfies:

[0123] [[ID=4I]]

[0124] wherein, V i b is the output after crosstalk elimination of channel i; V j is the output of the crosstalk channel j; i = 1, 2... n (natural numbers); j = 1, 2... n (natural numbers). The following is the crosstalk elimination formula for the multi-channel superconducting quantum interference measurement system 1 with 3 channels:

[0125]

[0126] It should be noted that the above steps realize the crosstalk calibration and elimination of the external feedback mode. For the superconducting quantum interference instrument measurement system with only the external feedback mode, the lossless crosstalk calibration has been completed. For the superconducting quantum interference instrument measurement system that takes into account both internal and external feedback modes, the present invention also needs to complete the lossless crosstalk calibration of the external feedback mode on the basis of the crosstalk calibration of the external feedback mode; then the present invention also includes step 2) adjusting the multi-channel superconducting quantum interference instrument measurement system 1 to the internal feedback mode, calibrating the channel crosstalk coefficient caused by the internal feedback coil in the multi-channel superconducting quantum interference instrument measurement system, and eliminating the crosstalk of the internal feedback mode by physical deduction based on the channel crosstalk coefficient caused by the pickup coil and the internal feedback coil.

[0127] First, the multi-channel superconducting quantum interference device measurement system 1 is set to internal feedback mode. The SQUID measurement module 13 is then placed in the working area of the high-performance coil 12 (as another example, the high-performance coil 12 is pre-placed in the magnetic shielding room 16 to provide a low-noise background magnetic field) and calibration begins. It should be noted that in this example, in internal feedback mode, the input coil and the internal feedback coil are mutually inductive, and the feedback signal is sensed by the input coil and fed back to the readout circuit.

[0128] The method for calibrating the channel crosstalk coefficient caused by the internal feedback coil further includes:

[0129] 21) Controlling the crosstalked channel and the crosstalk channel to be in a normal locked state, simulating the actual measured magnetic field, and generating a second constant magnetic field in the crosstalked channel and the crosstalk channel, obtaining a sixth voltage output by the crosstalked channel and a seventh voltage output by the crosstalk channel.

[0130] Specifically, in this embodiment, the measurement and control component 14 adjusts the operating parameters of the crosstalk channel i (i.e., the crosstalk channel to be calibrated) and the crosstalk channel j in the SQUID measurement component 131 via the SQUID readout circuit 132, so that the crosstalk channel i and the crosstalk channel j are both in a normal locked state. The high-performance coil 12 is used to simulate the actual measured magnetic field, and a second constant magnetic field with an intensity equal to or of the same magnitude as the actual measured magnetic field is generated in the crosstalk channel i and the crosstalk channel j, and the sixth voltage V output by the crosstalk channel is measured and recorded. i outA1 and the seventh voltage output by the crosstalk channel

[0131] It should be noted that the magnitude of the second constant magnetic field may be equal to or different from that of the first constant magnetic field, which can be set according to actual needs and will not be specifically limited here.

[0132] 22) Reset the crosstalk channel, and obtain the eighth voltage output by the crosstalk-affected channel and the ninth voltage output by the crosstalk channel.

[0133] Specifically, in this embodiment, the crosstalk channel i in the SQUID measurement component 131 is reset through the measurement and control component 14 via the SQUID readout circuit 132, and the eighth voltage V output by the crosstalk-affected channel is measured and recorded. i outA2 and the ninth voltage output by the crosstalk channel

[0134] 23) Calculate the channel crosstalk coefficient between the crosstalk-affected channel and the crosstalk channel caused by the internal feedback coil based on the sixth voltage, the seventh voltage, the eighth voltage, and the ninth voltage.

[0135] Specifically, the crosstalk coefficient corresponding to the internal feedback coil used in the internal feedback mode is obtained through mathematical calculation, satisfying:

[0136]

[0137] where m ij is the channel crosstalk coefficient between the crosstalk-affected channel i and the crosstalk channel j caused by the internal feedback coil in the internal feedback mode; V i outA1 is the sixth voltage output by the crosstalk-affected channel i (the output of the crosstalk-affected channel i after applying the second constant magnetic field and being in the Lock state); V i outA2 is the eighth voltage output by the crosstalk-affected channel i (the output of the crosstalk-affected channel i after applying the second constant magnetic field and resetting the crosstalk channel j); is the seventh voltage output by the crosstalk channel j (the output of the crosstalk channel j after applying the second constant magnetic field and being in the Lock state); is the ninth voltage output by the crosstalk channel j (the output of the crosstalk channel j after applying the second constant magnetic field, resetting, and being in the Lock state).

[0138] 24) Select different crosstalk channels and crosstalk-affected channels to execute the above steps 21) to 23) to obtain the channel crosstalk coefficient matrix of the multi-channel superconducting quantum interference device measurement system in the internal feedback mode.

[0139] Specifically, by means of traversal, different crosstalk channels j and the crosstalked channels i are sequentially selected to obtain the channel crosstalk coefficient matrix of the multi-channel superconducting quantum interference device measurement system, and then, according to the output value of the crosstalk channel j in the actual working state, the crosstalk of the crosstalked channel is eliminated in a physical offset manner. The output after crosstalk elimination satisfies:

[0140]

[0141] Wherein, V i b is the output after crosstalk elimination of channel i; V j is the output of the crosstalk channel j; is the channel crosstalk coefficient caused by the pickup coil between the crosstalked channel i and the crosstalk channel j; is the magnitude of the second constant magnetic field loaded on channel i; i = 1, 2... n (natural numbers); j = 1, 2... n (natural numbers). The following is the crosstalk elimination formula for the multi-channel superconducting quantum interference device measurement system 1 with 3 channels:

[0142]

[0143] Based on the working characteristics of SQUID, the present invention proposes a non-destructive calibration method for crosstalk of a multi-channel SQUID measurement system. In an environment where the change of the background magnetic field can be ignored, a constant magnetic field equal to or of the same order of magnitude as the actual measured magnetic field strength is simulated by a high-performance coil. By using the unique flux locking and flux jump characteristics of SQUID, the working state of the crosstalk channel SQUID is changed in constant magnetic fields of different intensities, and the output change values of the crosstalked channels when affected by the crosstalk of both the Pickup coil and the Feedback coil and when only affected by the crosstalk of the Pickup coil are measured. Furthermore, the crosstalk coefficients between channels are obtained according to the amplitude of the loaded magnetic field and the output of the crosstalk channel, and the channel crosstalk coefficient matrix of the SQUID measurement system is obtained by selecting different crosstalk channels in a traversal manner, thereby eliminating crosstalk. The present invention can not only improve the accuracy of crosstalk calibration and simplify the measurement steps of crosstalk, but also realize crosstalk calibration without damage without changing the multi-channel SQUID measurement system.

[0144] Embodiment III

[0145] This embodiment provides a non-destructive crosstalk calibration method for a multi-channel superconducting quantum interference device measurement system. The crosstalk calibration method for each coil in this embodiment is different from that in Embodiment 2. In the traditional method, heating is used to quench the pick-up coil, and non-destructive calibration cannot be achieved. In this embodiment, the fluidity or volatility of liquid helium is used to replace the traditional heating method to quench the pick-up coil, so as to achieve non-destructive crosstalk calibration on the basis of the traditional method. Among them, using the fluidity or volatility of liquid helium to replace heating to quench the pick-up coil requires that the multi-channel superconducting quantum interference device meets the requirement of quenching successively as the liquid helium level drops (for the case where the requirement of quenching successively as the liquid helium level drops cannot be met, non-destructive calibration can be achieved based on the method in Embodiment 2).

[0146] Specifically, the method for calibrating the channel crosstalk coefficient caused by the external feedback coil in step 1) includes:

[0147] 121) By tilting the dewar to control the fluidity of liquid helium or using the volatility of liquid helium, control the crosstalked channel to be in the superconducting state and the crosstalking channel to be in the non-superconducting state.

[0148] 122) Control the crosstalked channel to be in the normal locking state, control the crosstalking channel to be in the no-feedback mode and adjust the crosstalking channel not to respond to the external magnetic field and the output to tend to zero, and obtain the tenth voltage V output by the crosstalked channel i out10 .

[0149] 123) Load a crosstalk test signal from the output port of the crosstalking channel, and obtain the eleventh voltage V output by the crosstalked channel i out11 and the twelfth voltage loaded by the crosstalking channel

[0150] 124) Based on the tenth voltage V i out10 , the eleventh voltage V i out11 and the twelfth voltage calculate the channel crosstalk coefficient caused by the external feedback coil, satisfying:

[0151]

[0152] where k ij is the channel crosstalk coefficient caused by the external feedback coil between the crosstalked channel i and the crosstalking channel j in the external feedback mode; V i out10 is the tenth voltage output by the crosstalked channel i; V i out11 is the eleventh voltage output by the crosstalked channel i; The twelfth voltage loaded for the crosstalk channel j.

[0153] Specifically, the method for calibrating the channel crosstalk coefficient caused by the pickup coil in step 1) includes:

[0154] 131) Utilizing the fluidity or volatility of liquid helium, first, control both the crosstalked channel and the crosstalk channel to be in the superconducting state.

[0155] 132) Control the crosstalked channel to be in the normal locked state, control the crosstalk channel to be in the no-feedback mode and adjust the crosstalk channel not to respond to the external magnetic field and the output to tend to zero, and generate a third constant magnetic field in the crosstalked channel and the crosstalk channel, and obtain the fifteenth voltage V output by the crosstalked channel i out15 .

[0156] 133) Utilizing the volatility of liquid helium, control the crosstalked channel to be in the superconducting state while the crosstalk channel is in the non-superconducting state.

[0157] 134) Generate a third constant magnetic field in the crosstalked channel and the crosstalk channel, and obtain the sixteenth voltage V output by the crosstalked channel i out16 .

[0158] 135) Based on the fifteenth voltage V i out15 , the sixteenth voltage V i out16 calculate the channel crosstalk coefficient caused by the pickup coil, satisfying:

[0159]

[0160] where, is the channel crosstalk coefficient caused by the pickup coil between the crosstalked channel i and the crosstalk channel j; is the magnitude of the third constant magnetic field; V i out15 is the fifteenth voltage output by the crosstalked channel i; V i out16 is the sixteenth voltage output by the crosstalked channel i.

[0161] As another implementation manner of the present invention, the method for obtaining the channel crosstalk coefficient caused by the pickup coil may also include: substituting k in this embodiment ij for k in the second embodiment ij and substituting it into formula (2), and repeating steps 111) and 112) in the second embodiment, then the can be obtained. Details are not described one by one here.

[0162] It should be noted that by selecting different crosstalk channels and crosstalked channels and repeating the above steps, a channel crosstalk coefficient matrix can be obtained to achieve crosstalk elimination. For detailed steps, see Example 2, which will not be repeated here. The above steps realize the crosstalk calibration and elimination of the external feedback mode. For a superconducting quantum interference instrument measurement system with only an internal feedback mode, the channel crosstalk coefficient caused by the internal feedback coil and the channel crosstalk coefficient caused by the pickup coil are obtained. The solution method of the internal and external feedback modes in this embodiment can be used. See steps 121)-124) and 131)-135 for details. For a superconducting quantum interference instrument measurement system that takes into account both internal and external feedback modes, the channel crosstalk coefficient caused by the external feedback coil and the pickup coil can be obtained in the external feedback mode. On the basis of the calibration method of the channel crosstalk coefficient caused by the external feedback coil in the present embodiment (the external feedback mode is adjusted to the internal feedback mode), see steps 121)-124) for details, which will not be repeated here.

[0163] In summary, the present invention provides a multi-channel superconducting quantum interference instrument measurement system and a lossless crosstalk calibration method, which comprises the following steps: 1) adjusting the multi-channel superconducting quantum interference instrument measurement system to an external feedback mode, calibrating the channel crosstalk coefficients caused by the pickup coil and the external feedback coil in the multi-channel superconducting quantum interference instrument measurement system, and eliminating the crosstalk of the external feedback mode by physical deduction based on the channel crosstalk coefficient caused by the external feedback coil; and 2) adjusting the multi-channel superconducting quantum interference instrument measurement system to an internal feedback mode, calibrating the channel crosstalk coefficient caused by the internal feedback coil in the multi-channel superconducting quantum interference instrument measurement system, and eliminating the crosstalk of the internal feedback mode by physical deduction based on the channel crosstalk coefficients caused by the pickup coil and the internal feedback coil. The multi-channel superconducting quantum interference instrument measurement system and the lossless crosstalk calibration method of the present invention can not only improve the accuracy of the crosstalk calibration while realizing the crosstalk calibration and elimination of the multi-channel SQUID measurement system with an integrated pickup coil, but also realize the crosstalk calibration non-destructively without changing the multi-channel SQUID measurement system. Furthermore, the calibration method constructed by the present invention is simple to implement and operate, making it very suitable for use in high-precision SQUID-based magnetic measurement fields such as supernavigation magnetism. Therefore, the present invention effectively overcomes the various shortcomings of the existing technology and has high industrial application value.

[0164] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A non-destructive crosstalk calibration method for a multi-channel superconducting quantum interference device measurement system, the multi-channel superconducting quantum interference device measurement system comprising: SQUID measurement module, high-performance coil, power signal source, measurement and control component, and crosstalk calibration module; The power signal source provides an excitation signal; The high-performance coil is connected to the power signal source and is used to generate a magnetic field; the SQUID measurement module is arranged in the working area of the high-performance coil and responds to the magnetic field generated by the high-performance coil; the measurement and control component is connected to the SQUID measurement module, sets the working parameters of the SQUID measurement module, and acquires the data of the SQUID measurement module; the crosstalk calibration module is connected to the output end of the measurement and control component and calculates the crosstalk coefficients between channels based on the output signal of the measurement and control component; it is characterized in that the non-destructive crosstalk calibration method at least includes: 1) Adjust the multi-channel superconducting quantum interference device measurement system to an external feedback mode, calibrate the channel crosstalk coefficients caused by the pickup coil and the external feedback coil in the multi-channel superconducting quantum interference device measurement system respectively, and eliminate the crosstalk of the external feedback mode by means of physical deduction based on the channel crosstalk coefficient caused by the external feedback coil; specifically including, 111) Control the crosstalked channel to be in a normal locked state, control the crosstalking channel to be in a non-feedback mode, and adjust the crosstalking channel not to respond to the external magnetic field and the output to tend to a zero value; simulate the actual measured magnetic field, and generate a first constant magnetic field in the crosstalked channel and the crosstalking channel, and obtain the first voltage output by the crosstalked channel; 112) Cancel the first constant magnetic field, control the crosstalking channel to be in a normal locked state, simulate the actual measured magnetic field again, and generate the first constant magnetic field in the crosstalked channel and the crosstalking channel, and obtain the second voltage output by the crosstalked channel; and obtain the third voltage output by the crosstalking channel in the feedback mode; 113) When the crosstalking channel is in a normal locked state, adjust the current of the external feedback coil, and obtain the fourth voltage output by the crosstalked channel; and obtain the fifth voltage output by the crosstalking channel in the normal locked state under the first constant magnetic field; 114) Calculate the channel crosstalk coefficient caused by the pickup coil between the crosstalked channel and the crosstalking channel based on the first voltage, the second voltage, the third voltage, and the first constant magnetic field, and calculate the channel crosstalk coefficient caused by the external feedback coil between the crosstalked channel and the crosstalking channel based on the second voltage, the third voltage, the fourth voltage, and the fifth voltage; 115) Select different crosstalking channels and crosstalked channels to execute the above steps 111) to 114) to obtain the channel crosstalk coefficient matrix of the multi-channel superconducting quantum interference device measurement system in the external feedback mode.

2. The non-destructive crosstalk calibration method according to claim 1, wherein: The method for adjusting the current of the external feedback coil in step 113) includes: adjusting the first constant magnetic field so that there is a fractional flux quantum in the magnetic flux corresponding to the SQUID working point of the crosstalking channel.

3. The non-destructive crosstalk calibration method according to claim 1, characterized in that: The method for adjusting the current of the external feedback coil in step 113) includes: after adjusting the operating parameters of the crosstalk channel to make the crosstalk channel in a normal locked state, adjusting the offset voltage of the crosstalk channel to change the current of the external feedback coil.

4. The non-destructive crosstalk calibration method according to claim 1, characterized in that: The method for adjusting the current of the external feedback coil in step 113) includes: adjusting the operating parameters of the crosstalk channel or changing the external electromagnetic environment to cause a flux jump within the range of the crosstalk channel, while the crosstalked channel does not have a flux jump.

5. The non-destructive crosstalk calibration method according to claim 1, wherein: The channel crosstalk coefficient caused by the external feedback coil satisfies: Among them, k ij is the channel crosstalk coefficient caused by the external feedback coil between the crosstalked channel i and the crosstalk channel j in the external feedback mode; V i out2 is the second voltage output by the crosstalked channel i; V i out4 is the fourth voltage output by the crosstalked channel i; The third voltage output for crosstalk channel j; The fifth voltage output for crosstalk channel j.

6. The non-destructive crosstalk calibration method according to claim 5, wherein: The channel crosstalk coefficient caused by the pickup coil satisfies: Among them, is the channel crosstalk coefficient caused by the pickup coil between the crosstalk-affected channel i and the crosstalk channel j; is the magnitude of the first constant magnetic field; V i out1 is the first voltage output by the crosstalk channel i; V i out2 is the second voltage output by the crosstalk channel i; is the third voltage output by the crosstalk channel j.

7. The non-destructive crosstalk calibration method according to claim 5, characterized in that: The output after crosstalk cancellation satisfies: Among them, V i b is the output after crosstalk cancellation for channel i; V j is the output of the crosstalk channel j; k ij is the channel crosstalk coefficient caused by the external feedback coil between the crosstalked channel i and the crosstalk channel j in the external feedback mode; i = 1, 2... n; j = 1, 2... n.

8. The crosstalk-free calibration method according to any one of claims 1-5, characterized in that: The non-destructive crosstalk calibration method further includes: 2) Adjust the multi-channel superconducting quantum interference measurement system to an internal feedback mode, calibrate the channel crosstalk coefficient caused by the internal feedback coil in the multi-channel superconducting quantum interference measurement system, and cancel the crosstalk in the internal feedback mode by physical deduction based on the channel crosstalk coefficients caused by the pickup coil and the internal feedback coil.

9. The non-destructive crosstalk calibration method according to claim 8, wherein: The method for calibrating the channel crosstalk coefficient caused by the internal feedback coil in step 2) includes: 21) Control both the crosstalked channel and the crosstalk channel to be in a normal locked state, simulate the actual magnetic field to be measured, and generate a second constant magnetic field in the crosstalked channel and the crosstalk channel, and obtain the sixth voltage output by the crosstalked channel and the seventh voltage output by the crosstalk channel; 22) Reset the crosstalk channel, and obtain the eighth voltage output by the crosstalked channel and the ninth voltage output by the crosstalk channel; 23) Calculate the channel crosstalk coefficient caused by the internal feedback coil between the crosstalked channel and the crosstalk channel based on the sixth voltage, the seventh voltage, the eighth voltage, and the ninth voltage; 24) Select different crosstalk channels and crosstalked channels to execute the above steps 21) to 23) to obtain the channel crosstalk coefficient matrix of the multi-channel superconducting quantum interference measurement system in the internal feedback mode.

10. The non-destructive crosstalk calibration method according to claim 9, characterized in that: The channel crosstalk coefficient caused by the internal feedback coil satisfies: where m ij is the channel crosstalk coefficient caused by the internal feedback coil between the crosstalked channel i and the crosstalk channel j in the internal feedback mode; V i outA1 is the sixth voltage output by the crosstalked channel i; V i outA2 is the eighth voltage output by the crosstalked channel i; The seventh voltage output for crosstalk channel j; The ninth voltage output for crosstalk channel j.

11. The non-destructive crosstalk calibration method according to claim 10, wherein: The output after crosstalk cancellation satisfies: Among them, V i b is the output after crosstalk cancellation for channel i; V j is the output of the crosstalk channel j; m ij is the channel crosstalk coefficient caused by the internal feedback coil between the crosstalked channel i and the crosstalk channel j in the internal feedback mode; is the channel crosstalk coefficient caused by the pickup coil between the crosstalked channel i and the crosstalk channel j; is the magnitude of the second constant magnetic field loaded on channel i; i = 1, 2... n; j = 1, 2... n.

12. The crosstalk-free calibration method according to claim 1, wherein: Utilize the fluidity or volatility of liquid helium to quench the pickup coil, thereby realizing non-destructive crosstalk calibration.

13. The non-destructive crosstalk calibration method according to claim 12, wherein: The method for calibrating the channel crosstalk coefficient caused by the feedback coil includes: 121) Control the fluidity of liquid helium by tilting the dewar or utilize the volatility of liquid helium to control the crosstalked channel to be in a superconducting state, while the crosstalk channel is in a non-superconducting state; 122) Control the crosstalked channel to be in a normal locked state, control the crosstalk channel to be in a no-feedback mode and adjust the crosstalk channel not to respond to the external magnetic field and the output tends to zero, and obtain the tenth voltage output by the crosstalked channel; 123) Load a crosstalk test signal from the output port of the crosstalk channel, and obtain the eleventh voltage output by the crosstalked channel and the twelfth voltage loaded on the crosstalk channel; 124) Calculate the channel crosstalk coefficient caused by the feedback coil based on the tenth voltage, the eleventh voltage, and the twelfth voltage, satisfying: where k ij is the channel crosstalk coefficient caused by the feedback coil between the crosstalked channel i and the crosstalk channel j in the corresponding feedback mode; V i out10 is the tenth voltage output by the crosstalked channel i; V i out11 is the eleventh voltage output by the crosstalked channel i; is the twelfth voltage loaded by the crosstalk channel j.

14. The non-destructive crosstalk calibration method according to claim 12, wherein: The method for calibrating the channel crosstalk coefficient caused by the feedback coil includes: 131) Control the crosstalk channel and the crosstalked channel to be in the superconducting state by utilizing the fluidity or volatility of liquid helium; 132) Control the crosstalked channel to be in the normal locked state, control the crosstalk channel to be in the no-feedback mode, adjust the crosstalk channel not to respond to the external magnetic field and the output to tend to zero, and generate a third constant magnetic field in the crosstalked channel and the crosstalk channel, and obtain the fifteenth voltage output by the crosstalked channel; 133) Control the crosstalked channel to be in the superconducting state by utilizing the fluidity or volatility of liquid helium, while the crosstalk channel is in the non-superconducting state; 134) Generate the third constant magnetic field in the crosstalked channel and the crosstalk channel, and obtain the sixteenth voltage output by the crosstalked channel; 135) Calculate the channel crosstalk coefficient caused by the pickup coil based on the fifteenth voltage and the sixteenth voltage, satisfying: Among them, is the channel crosstalk coefficient caused by the pickup coil between the crosstalk-affected channel i and the crosstalk channel j; is the magnitude of the third constant magnetic field; V i out15 is the fifteenth voltage output by the crosstalk-affected channel i; V i out16 is the sixteenth voltage output by the crosstalk-affected channel i.

15. The crosstalk-free calibration method according to claim 1, characterized in that: The SQUID measurement module includes a SQUID measurement component and a SQUID readout circuit. The SQUID readout circuit is connected to the SQUID measurement component to read the output data of the SQUID measurement component.

16. The non-destructive crosstalk calibration method according to claim 15, characterized in that: When the multi-channel superconducting quantum interference measurement system is used to eliminate crosstalk in the external feedback mode, the SQUID measurement component includes a pickup coil, an input coil, and an external feedback coil; when the multi-channel superconducting quantum interference measurement system is used to eliminate crosstalk in the internal feedback mode, the SQUID measurement component includes a pickup coil, an input coil, an external feedback coil, and an internal feedback coil.

17. The crosstalk-free calibration method according to claim 1, characterized in that: The multi-channel superconducting quantum interference measurement system further includes a magnetic shielding chamber, and the high-performance coil is placed in the magnetic shielding chamber.

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