Superconducting quantum interference circuit and integrated chip

Abstract

The invention discloses a superconducting quantum interference circuit and an integrated chip. The circuit comprises a first superconducting quantum interference device; the positive feedback circuit comprises a first inductance coil of which the coupling polarity with the first superconducting quantum interference device is positive; the negative feedback circuit comprises a second inductance coil of which the coupling polarity with the first superconducting quantum interference device is negative; and the feedback polarity adjusting module is used for providing a turn-off signal for one of the positive feedback circuit and the negative feedback circuit, so that one of the positive feedback circuit and the negative feedback circuit is not coupled with the first superconducting quantum interference device, and the other one is coupled with the first superconducting quantum interference device. According to the embodiment of the invention, positive and negative switching can be carried out on the coupling polarity between the superconducting quantum interference device and the feedback circuit so as to adapt to different application scenes, and the applicability and multifunctionality of the superconducting quantum interference circuit are improved.

Description

Technical Field

[0001] The present application belongs to the technical field of superconducting quantum devices, and in particular, relates to a superconducting quantum interference circuit and an integrated chip. Background Art

[0002] Superconducting quantum interference device (SQUID) is an extremely sensitive magnetic flux sensor at low temperatures. Due to its low input impedance, low intrinsic noise and low power consumption, SQUID is widely used in high-precision electromagnetic signal measurement.

[0003] In the actual measurement process, the setting parameters and feedback circuits of the superconducting quantum interference device need to be designed accordingly according to the actual application scenario. For example, a single SQUID system includes a superconducting quantum interference device and the room temperature electronics of the SQUID. In the use scenario of measuring weak signals, in order to suppress the noise of the amplifier in room temperature electronics, it is necessary to introduce a corresponding feedback circuit to increase the flux-voltage conversion coefficient or the flux-current conversion coefficient; and when reading the low-temperature detector signal, in order to avoid nonlinear distortion of the detector signal, it is necessary to introduce an opposite feedback circuit to increase the linear flux range.

[0004] However, SQUID systems are usually designed only for a certain usage scenario and cannot achieve multifunctional applications in different usage scenarios. Summary of the invention

[0005] The embodiments of the present application provide a superconducting quantum interference circuit and an integrated chip, which can solve the technical problem that superconducting quantum interference devices cannot be applied to different scenarios.

[0006] In a first aspect, an embodiment of the present application provides a superconducting quantum interference circuit, the superconducting quantum interference circuit comprising:

[0007] The first superconducting quantum interference device;

[0008] A positive feedback circuit, comprising a first inductor coil having a positive coupling polarity with the first superconducting quantum interference device;

[0009] A negative feedback circuit, comprising a second inductor coil having a negative coupling polarity with the first superconducting quantum interference device;

[0010] The feedback polarity adjustment module is used to provide a shutdown signal for one of the positive feedback circuit and the negative feedback circuit, so that one of the positive feedback circuit and the negative feedback circuit is decoupled from the first superconducting quantum interference device and the other is coupled to the first superconducting quantum interference device.

[0011] In some embodiments, the positive feedback circuit further comprises:

[0012] A first superconducting switch is connected in series with the first inductor, and is used to disconnect the first inductor from the first superconducting quantum interference device when the feedback polarity adjustment module provides a half-integer multiple of magnetic flux quanta to the first superconducting switch;

[0013] Negative feedback circuits also include:

[0014] The second superconducting switch is connected in series with the second inductor and is used to disconnect the second inductor from the first superconducting quantum interference device when the feedback polarity adjustment module provides a half-integer multiple of magnetic flux quanta for the second superconducting switch.

[0015] In some embodiments, the first superconducting switch includes a plurality of second superconducting quantum interference devices connected in series, and the second superconducting switch includes a plurality of second superconducting quantum interference devices connected in series; wherein,

[0016] The shielding parameter β corresponding to the loop inductance of the second superconducting quantum interference device L <<1.

[0017] In some embodiments, the feedback polarity adjustment module includes:

[0018] A magnetic flux bias line is inductively coupled with each second superconducting quantum interference device of one of the first superconducting switch and the second superconducting switch; the magnetic flux bias line is used to provide a first bias current that generates a half-integer multiple of magnetic flux quanta with each second superconducting quantum interference device;

[0019] The control current line is inductively coupled with each second superconducting quantum interference device of the first superconducting switch and each second superconducting quantum interference device of the second superconducting switch; the control current line is used to provide a first control current that generates an integer multiple of magnetic flux quanta with each second superconducting quantum interference device, or to provide a second control current that generates a half-integer multiple of magnetic flux quanta with each second superconducting quantum interference device.

[0020] In some embodiments, the positive feedback circuit further includes a first resistor connected in series with the first inductor, and the negative feedback circuit further includes a second resistor connected in series with the second inductor;

[0021] The first resistor and the second resistor are titanium / platinum double-layer metals.

[0022] In some embodiments, the first superconducting quantum interference device, the first resistor, the first inductor, and the first superconducting switch are connected by a superconducting wire;

[0023] The first superconducting quantum interference device, the second resistor, the second inductor and the second superconducting switch are connected through a superconducting wire.

[0024] In some embodiments, the superconducting quantum interference circuit further comprises:

[0025] A current bias line connected to the first superconducting quantum interference device and used to provide a second bias current; the second bias current is used to drive the first superconducting quantum interference device to maintain a current bias mode;

[0026] The second bias current is greater than a critical current of the first superconducting quantum interference device, and the second bias current is less than a critical current of the first superconducting switch and a critical current of the second superconducting switch.

[0027] In some embodiments, the first inductor coil and the second inductor coil are coiled metal niobium superconducting wires.

[0028] In some embodiments, the first superconducting quantum interference device is a direct current superconducting quantum interference device.

[0029] In a second aspect, an embodiment of the present application provides an integrated chip, comprising the superconducting quantum interference circuit of the first aspect.

[0030] Compared with the prior art, the superconducting quantum interference circuit and integrated chip provided in the embodiment of the present application can achieve corresponding polarity coupling between one of the positive feedback circuit and the negative feedback circuit by setting a feedback polarity adjustment module to provide a shutdown signal for one of the positive feedback circuit and the negative feedback circuit. When the feedback polarity adjustment module provides a shutdown signal for the positive feedback circuit, the first superconducting quantum interference device can be negatively coupled to the negative feedback circuit; when the feedback polarity adjustment module provides a shutdown signal for the negative feedback circuit, the first superconducting quantum interference device can be positively coupled to the positive feedback circuit. By providing a shutdown signal to the corresponding feedback circuit through the feedback polarity adjustment module, the superconducting quantum interference circuit can be adapted to multifunctional use in different usage scenarios, thereby improving the applicability and versatility of the superconducting quantum interference circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 It is a schematic diagram of the module structure of a superconducting quantum interference circuit provided in one embodiment of the present application;

[0033] Figure 2 1 is a schematic diagram of the circuit structure of a superconducting quantum interference circuit provided in one embodiment of the present application;

[0034] Figure 3It is a schematic diagram of coupling a flux bias line and a control current line with a superconducting switch respectively provided in an embodiment of the present application.

[0035] In the attached figure:

[0036] SQ1, first superconducting quantum interference device; 10, positive feedback circuit; 20, negative feedback circuit; 30, feedback polarity adjustment module; L1, first inductor; L2, second inductor; SW1, first superconducting switch; SW2, second superconducting switch; SQ2, second superconducting quantum interference device; R1, first resistor; R2, second resistor; FL1, flux bias line; CC1, control current line; CB1, current bias line. DETAILED DESCRIPTION

[0037] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, rather than to limit the present application. For those skilled in the art, the present application can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present application by illustrating the examples of the present application.

[0038] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "include..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0039] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The embodiments will be described in detail below in conjunction with the accompanying drawings.

[0040] Superconducting quantum interference device (SQUID) is an extremely sensitive magnetic flux sensor at low temperatures. Due to its low input impedance, low intrinsic noise and low power consumption, SQUID is widely used in high-precision electromagnetic signal measurement.

[0041] In the actual measurement process, the setting parameters and feedback circuits of the superconducting quantum interference device need to be designed accordingly according to the actual application scenario. For example, a single SQUID system includes a superconducting quantum interference device and the room temperature electronics of the SQUID. In the use scenario of measuring weak signals, in order to suppress the noise of the amplifier in room temperature electronics, it is necessary to introduce a corresponding feedback circuit to increase the flux-voltage conversion coefficient or the flux-current conversion coefficient; and when reading the low-temperature detector signal, in order to avoid nonlinear distortion of the detector signal, it is necessary to introduce an opposite feedback circuit to increase the linear flux range.

[0042] However, SQUID systems are usually designed only for a certain usage scenario and cannot achieve multifunctional applications in different usage scenarios.

[0043] In order to solve the above technical problems, the embodiments of the present application provide a superconducting quantum interference circuit and an integrated chip. The superconducting quantum interference circuit provided by the embodiments of the present application is first introduced below.

[0044] Figure 1 The schematic diagram of the structure of a superconducting quantum interference circuit provided by an embodiment of the present application is shown. The superconducting quantum interference circuit includes a first superconducting quantum interference device SQ1, a positive feedback circuit 10, a negative feedback circuit 20 and a feedback polarity adjustment module 30.

[0045] The first superconducting quantum interference device SQ1 may be a direct current superconducting quantum interference device, which is composed of two parallel Josephson junctions, and the two Josephson junctions are connected in parallel in a superconducting loop. The direct current superconducting quantum interference device can be prepared based on a standard Josephson niobium junction process, that is, a standard niobium-aluminum / aluminum oxide-niobium process.

[0046] The positive feedback circuit 10 includes a first inductor L1. When the positive feedback circuit 10 is coupled with the first superconducting quantum interference device SQ1, the coupling polarity between the first inductor L1 and the first superconducting quantum interference device SQ1 is positive.

[0047] The negative feedback circuit 20 includes a second inductor L2. When the negative feedback circuit 20 is coupled to the first superconducting quantum interference device SQ1, the coupling polarity between the second inductor L2 and the first superconducting quantum interference device SQ1 is negative.

[0048] The feedback polarity adjustment module 30 can provide a shutdown signal for one of the positive feedback circuit 10 and the negative feedback circuit 20, so that one of the positive feedback circuit 10 and the negative feedback circuit 20 is decoupled from the first superconducting quantum interference device SQ1, and the other is coupled to the first superconducting quantum interference device SQ1.

[0049] In an exemplary embodiment, the feedback polarity adjustment module 30 can provide a shutdown signal for the positive feedback circuit 10. At this time, the positive feedback circuit 10 is uncoupled from the first superconducting quantum interference device SQ1, the negative feedback circuit 20 is coupled to the first superconducting quantum interference device SQ1, and the first superconducting quantum interference device SQ1 is negatively coupled to the second inductor L2 in the negative feedback circuit 20. The negative feedback circuit 20 can increase the linear magnetic flux range of the first superconducting quantum interference device SQ1, thereby improving the nonlinear distortion problem of the detector signal in the usage scenario of reading the low-temperature detector signal.

[0050] Similarly, the feedback polarity adjustment module 30 can also provide a shutdown signal for the negative feedback circuit 20. At this time, the negative feedback circuit 20 is uncoupled from the first superconducting quantum interference device SQ1, the positive feedback circuit 10 is coupled to the first superconducting quantum interference device SQ1, and the first superconducting quantum interference device SQ1 is positively coupled to the first inductor L1 in the positive feedback circuit 10. The positive feedback circuit 10 can increase the flux-voltage conversion coefficient or the flux-current conversion coefficient of the first superconducting quantum interference device SQ1, thereby effectively suppressing the noise of the amplifier in room temperature electronics in the use scenario of measuring weak signals.

[0051] In this embodiment, by setting the feedback polarity adjustment module 30 to provide a shutdown signal to one of the positive feedback circuit 10 and the negative feedback circuit 20, one of the positive feedback circuit 10 and the negative feedback circuit 20 can be coupled with the first superconducting quantum interference device SQ1 in a corresponding polarity. When the feedback polarity adjustment module 30 provides a shutdown signal to the positive feedback circuit 10, the first superconducting quantum interference device SQ1 can be coupled with the negative feedback circuit 20 in a negative polarity; when the feedback polarity adjustment module 30 provides a shutdown signal to the negative feedback circuit 20, the first superconducting quantum interference device SQ1 can be coupled with the positive feedback circuit 10 in a positive polarity. By providing a shutdown signal to the corresponding feedback circuit through the feedback polarity adjustment module 30, the superconducting quantum interference circuit can be adapted to multifunctional use in different usage scenarios, thereby improving the applicability and versatility of the superconducting quantum interference circuit.

[0052] Please refer to Figure 2 In some embodiments, the positive feedback circuit 10 may further include a first superconducting switch SW1. The first superconducting switch SW1 is connected in series with the first inductor L1. The negative feedback circuit 20 may further include a second superconducting switch SW2. The second superconducting switch SW2 is connected in series with the second inductor L2.

[0053] The feedback polarity adjustment module 30 may provide a shutdown signal to the positive feedback circuit 10 by providing a half-integer multiple of magnetic flux quanta to the first superconducting switch SW1. When the first superconducting switch SW1 receives a half-integer multiple of magnetic flux quanta, the critical current of the first superconducting switch SW1 decreases. At this time, the actual current on the positive feedback circuit 10 is greater than the critical current of the first superconducting switch SW1, so that the first superconducting switch SW1 loses its superconducting state, and the resistance reappears, resulting in a corresponding increase in the loop resistance of the positive feedback circuit 10. At this time, the negative feedback circuit 20 does not receive the shutdown signal, and the second superconducting switch SW2 remains in the superconducting state.

[0054] When the first superconducting switch SW1 loses its superconducting state and the second superconducting switch SW2 maintains its superconducting state, it is equivalent to that the first superconducting quantum interference device SQ1 is decoupled from the positive feedback circuit 10, and the first superconducting quantum interference device SQ1 is coupled to the negative feedback circuit 20. At this time, the first superconducting quantum interference device SQ1 is negatively coupled to the second inductor L2.

[0055] Similarly, the feedback polarity adjustment module 30 can also provide a half-integer multiple of the magnetic flux quantum to the second superconducting switch SW2 to provide a shutdown signal to the negative feedback circuit 20. When the second superconducting switch SW2 receives the half-integer multiple of the magnetic flux quantum, the critical current is reduced. At this time, the actual current on the negative feedback circuit 20 is greater than the critical current of the second superconducting switch SW2, so that the second superconducting switch SW2 loses its superconducting state, and the resistance reappears, resulting in a corresponding increase in the loop resistance of the negative feedback circuit 20. At this time, the positive feedback circuit 10 does not receive the shutdown signal, and the first superconducting switch SW1 remains in the superconducting state.

[0056] When the second superconducting switch SW2 loses its superconducting state and the first superconducting switch SW1 maintains its superconducting state, the first superconducting quantum interference device SQ1 is decoupled from the negative feedback circuit 20, and the first superconducting quantum interference device SQ1 is coupled to the positive feedback circuit 10. At this time, the first superconducting quantum interference device SQ1 is positively coupled to the first inductor L1.

[0057] Please refer to Figure 3 In some embodiments, the first superconducting switch SW1 may include a plurality of second superconducting quantum interference devices SQ2 connected in series, and the second superconducting switch SW2 may include a plurality of second superconducting quantum interference devices SQ2 connected in series.

[0058] The second superconducting quantum interference device SQ2 may be a superconducting quantum interference device with low loop inductance. When the second superconducting quantum interference device SQ2 has a lower loop inductance value, the corresponding shielding parameter is much smaller than 1, that is, β L<<1. Setting the second superconducting quantum interference device SQ2 to have a low loop inductance can effectively reduce the inductive coupling between the second superconducting quantum interference device SQ2 and other devices in the circuit.

[0059] In an optional implementation, the loop inductance of the second superconducting quantum interference device SQ2 can be set to be lower than the loop inductance of the first superconducting quantum interference device SQ1. When the first superconducting quantum interference device SQ1 is positively coupled with the first inductor coil L1 in the positive feedback circuit 10 or negatively coupled with the second inductor coil L2 in the negative feedback circuit 20, the loop inductance of the second superconducting quantum interference device SQ2 is small, and the degree of coupling with other inductors is small.

[0060] Please continue to refer to Figure 2 In some embodiments, the feedback polarity adjustment module 30 may include a flux bias line FL1 and a control current line CC1.

[0061] The flux bias line FL1 may be inductively coupled to one of the first superconducting switch SW1 and the second superconducting switch SW2 .

[0062] like Figure 2 and Figure 3 As shown, taking the inductive coupling between the magnetic flux bias line FL1 and the second superconducting switch SW2 as an example, the magnetic flux bias line FL1 can be inductively coupled with each second superconducting quantum interference device SQ2 in the second superconducting switch SW2, and the magnetic flux generated by the coupling of the first bias current provided by the magnetic flux bias line FL1 and each second superconducting quantum interference device SQ2 corresponds to a half-integer multiple of the magnetic flux quantum.

[0063] Similarly, if the flux bias line FL1 is set to be inductively coupled with the first superconducting switch SW1, the flux bias line FL1 can be inductively coupled with each second superconducting quantum interference device SQ2 in the first superconducting switch SW1, and the magnetic flux generated by the first bias current provided by the flux bias line FL1 and coupling with each second superconducting quantum interference device SQ2 corresponds to a half-integer multiple of the flux quantum.

[0064] The control current line CC1 may be inductively coupled to the first superconducting switch SW1 and the second superconducting switch SW2 , respectively.

[0065] like Figure 2 and Figure 3 As shown, the control current line CC1 can be inductively coupled with each second superconducting quantum interference device SQ2 of the first superconducting switch SW1 and each second superconducting quantum interference device SQ2 of the second superconducting switch SW2.

[0066] The control current line CC1 can provide a first control current or a second control current. When the control current line CC1 outputs the first control current, the first control current can be coupled with each second superconducting quantum interference device SQ2 in the first superconducting switch SW1 and each second superconducting quantum interference device SQ2 in the second superconducting switch SW2, and generate a magnetic flux corresponding to an integer multiple of the magnetic flux quantum.

[0067] When the control current line CC1 outputs the second control current, the second control current can be coupled with each second superconducting quantum interference device SQ2 in the first superconducting switch SW1 and each second superconducting quantum interference device SQ2 in the second superconducting switch SW2, and generate a magnetic flux corresponding to a half-integer multiple of the magnetic flux quantum.

[0068] Taking the inductive coupling between the magnetic flux bias line FL1 and the second superconducting switch SW2 as an example, when the control current line CC1 outputs the first control current, each second superconducting quantum interference device SQ2 in the second superconducting switch SW2 can be coupled with the magnetic flux bias line FL1 to generate a half-integer multiple of magnetic flux quanta, and coupled with the control current line CC1 to generate an integer multiple of magnetic flux quanta. Then, each second superconducting quantum interference device SQ2 in the second superconducting switch SW2 generates a magnetic flux corresponding to a half-integer multiple of magnetic flux quanta under the common coupling of the magnetic flux bias line FL1 and the control current line CC1. At this time, each second superconducting quantum interference device SQ2 in the second superconducting switch SW2 loses the superconducting state under the half-integer multiple of magnetic flux quanta, which is equivalent to the second superconducting switch SW2 being in the disconnected state, and the second inductor L2 in the negative feedback circuit 20 is uncoupled from the first superconducting quantum interference device SQ1.

[0069] When the control current line CC1 outputs the first control current, each second superconducting quantum interference device SQ2 in the first superconducting switch SW1 is not coupled with the magnetic flux bias line FL1, but is only coupled with the control current line CC1 to generate an integer multiple of magnetic flux quanta. At this time, each second superconducting quantum interference device SQ2 in the first superconducting switch SW1 maintains a superconducting state under an integer multiple of magnetic flux quanta, which is equivalent to the first superconducting switch SW1 being in a conducting state, and the first inductor L1 in the positive feedback circuit 10 is turned on with the first superconducting quantum interference device SQ1.

[0070] When the control current line CC1 outputs the second control current, each second superconducting quantum interference device SQ2 in the second superconducting switch SW2 generates a magnetic flux corresponding to an integer multiple of the magnetic flux quantum under the common coupling of the magnetic flux bias line FL1 and the control current line CC1, and each second superconducting quantum interference device SQ2 in the first superconducting switch SW1 generates a magnetic flux corresponding to a half-integer multiple of the magnetic flux quantum under the coupling of the control current line CC1. At this time, the first superconducting switch SW1 is equivalent to the disconnected state, and the second superconducting switch SW2 is equivalent to the on state.

[0071] Therefore, when the flux bias line FL1 is inductively coupled with the second superconducting switch SW2, the control current line CC1 outputs the first control current to provide a shutdown signal for the negative feedback circuit 20, so that the first superconducting quantum interference device SQ1 is coupled with the positive feedback circuit 10; the control current line CC1 outputs the second control current to provide a shutdown signal for the positive feedback circuit 10, so that the first superconducting quantum interference device SQ1 is coupled with the negative feedback circuit 20.

[0072] In another embodiment, if the flux bias line FL1 is inductively coupled with the first superconducting switch SW1, the control current line CC1 outputs a first control current that can provide a shutdown signal for the positive feedback circuit 10, so that the first superconducting quantum interference device SQ1 is coupled with the negative feedback circuit 20; the control current line CC1 outputs a second control current that can provide a shutdown signal for the negative feedback circuit 20, so that the first superconducting quantum interference device SQ1 is coupled with the positive feedback circuit 10.

[0073] It should be noted that when the control current line CC1 does not output the control current, in the first superconducting switch SW1 and the second superconducting switch SW2, each second superconducting quantum interference device SQ2 in the superconducting switch coupled to the magnetic flux bias line FL1 loses the superconducting state under the half-integer multiple magnetic flux quantum, and each second superconducting quantum interference device SQ2 in the superconducting switch not coupled to the magnetic flux bias line FL1 maintains the superconducting state. That is, when the control current line CC1 does not output the control current, the superconducting switch coupled to the magnetic flux bias line FL1 is equivalent to being disconnected, and the superconducting switch not coupled to the magnetic flux bias line FL1 is equivalent to being turned on.

[0074] Please refer to Figure 2 In some embodiments, the positive feedback circuit 10 may further include a first resistor R1 connected in series with the first inductor L1, and the negative feedback circuit 20 may further include a second resistor R2 connected in series with the second inductor L2.

[0075] The first resistor R1 and the second resistor R2 may be titanium / platinum double-layer metal. Taking the first resistor R1 as an example, the first resistor R1 may be a block resistor formed by a titanium / platinum double-layer metal, and the resistance of the block resistor is related to the thickness of titanium and the thickness of platinum. The first resistor R1 may be composed of a plurality of block resistors connected in series, and the resistance of the first resistor R1 is the sum of the resistances of the plurality of block resistors.

[0076] Similarly, the second resistor R2 is similar to the first resistor R1 and may also be a block resistor formed by a titanium / platinum double-layer metal, which will not be described in detail herein.

[0077] In an optional implementation, in a sheet resistor formed by a titanium / platinum double-layer metal, the thickness of titanium can be set to 10 nm, and the thickness of platinum can be set to 100 nm.

[0078] In some embodiments, the first superconducting quantum interference device SQ1, the first resistor R1, the first inductor L1 and the first superconducting switch SW1 may be connected via a superconducting wire, and the first superconducting quantum interference device SQ1, the second resistor R2, the second inductor L2 and the second superconducting switch SW2 may be connected via a superconducting wire.

[0079] The superconducting quantum interference device must work in a low temperature environment that causes it to enter a superconducting state. Therefore, the first superconducting quantum interference device SQ1, the first superconducting switch SW1, and the second superconducting switch SW2 should be set in an environment with a temperature lower than the superconducting critical transition temperature. In order to avoid the influence of the line resistance of the connection line between the first superconducting quantum interference device SQ1 and the positive feedback circuit 10 on the superconducting quantum interference circuit, the first superconducting quantum interference device SQ1 and the first resistor R1, the first inductor L1 and the first superconducting switch SW1 in the positive feedback circuit 10 can be connected by a superconducting wire. Similarly, in order to avoid the influence of the line resistance of the connection line between the first superconducting quantum interference device SQ1 and the negative feedback circuit 20, the first superconducting quantum interference device SQ1 and the second resistor R2, the second inductor L2 and the second superconducting switch SW2 in the negative feedback circuit 20 can be connected by a superconducting wire.

[0080] In some embodiments, the superconducting quantum interference circuit may further include a current bias line CB1.

[0081] The current bias line CB1 may be connected to the first superconducting quantum interference device SQ1 to provide a second bias current to the first superconducting quantum interference device SQ1. The second bias current may drive the first superconducting quantum interference device SQ1 to maintain a current bias mode.

[0082] The second bias current can be set to be slightly larger than the critical current of the first superconducting quantum interference device SQ1, and smaller than the critical current of the first superconducting switch SW1 and the critical current of the second superconducting switch SW2. Under the second bias current, the first superconducting quantum interference device SQ1 loses the ability to carry current with zero resistance, that is, the first superconducting quantum interference device SQ1 does not maintain a superconducting state. The second bias current is smaller than the critical current of the first superconducting switch SW1 and the critical current of the second superconducting switch SW2, indicating that under the second bias current, the first superconducting switch SW1 maintains a superconducting state, and the second superconducting switch SW2 also maintains a superconducting state.

[0083] It should be noted that the critical current of the first superconducting switch SW1 is the critical current of the first superconducting switch SW1 under non-half-integer multiples of magnetic flux quantum. Under half-integer multiples of magnetic flux quantum, the critical current of the first superconducting switch SW1 is greatly reduced. At this time, the second bias current will be much larger than the critical current after the significant reduction. The first superconducting switch SW1 will have resistance again, so that the positive feedback circuit 10 is decoupled from the first superconducting quantum interference device SQ1. Similarly, the critical current of the second superconducting switch SW2 is the critical current of the second superconducting switch SW2 under non-half-integer multiples of magnetic flux quantum.

[0084] In some embodiments, the first inductor L1 and the second inductor L2 may be coiled metal niobium superconducting wires.

[0085] The embodiment of the present application also provides an integrated chip, which may include the superconducting quantum interference circuit provided by the embodiment of the present application.

[0086] The functional blocks shown in the above-described block diagram can be implemented as hardware, software, firmware or a combination thereof. When implemented in hardware, it can be, for example, an electronic circuit, an application specific integrated circuit (ASIC), appropriate firmware, a plug-in, a function card, etc. When implemented in software, the elements of the present application are programs or code segments that are used to perform the required tasks. The program or code segment can be stored in a machine-readable medium, or transmitted on a transmission medium or a communication link by a data signal carried in a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, optical fiber media, radio frequency (RF) links, etc. The code segment can be downloaded via a computer network such as the Internet, an intranet, etc.

[0087] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0088] This article uses specific examples to illustrate the principles and implementation methods of this application. The above examples are only used to help understand the methods and core ideas of this application. The above are only preferred implementation methods of this application. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, ordinary technicians in this technical field can make several improvements, modifications or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the concepts and technical solutions of this application to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. A superconducting quantum interference circuit, characterized in that: The superconducting quantum interference circuit comprises: The first superconducting quantum interference device; A positive feedback circuit, comprising a first inductor coil having a positive coupling polarity with the first superconducting quantum interference device; A negative feedback circuit, comprising a second inductor coil having a negative coupling polarity with the first superconducting quantum interference device; A feedback polarity adjustment module is used to provide a shutdown signal to one of the positive feedback circuit and the negative feedback circuit, so that one of the positive feedback circuit and the negative feedback circuit is decoupled from the first superconducting quantum interference device, and the other is coupled to the first superconducting quantum interference device.

2. The superconducting quantum interference circuit according to claim 1, characterized in that: The positive feedback circuit also includes: a first superconducting switch, connected in series with the first inductor, and configured to disconnect the first inductor from the first superconducting quantum interference device when the feedback polarity adjustment module provides a half-integer multiple of magnetic flux quanta to the first superconducting switch; The negative feedback circuit further comprises: The second superconducting switch is connected in series with the second inductor and is used to disconnect the second inductor from the first superconducting quantum interference device when the feedback polarity adjustment module provides a half-integer multiple of magnetic flux quanta for the second superconducting switch.

3. The superconducting quantum interference circuit according to claim 2, characterized in that: The first superconducting switch includes a plurality of second superconducting quantum interference devices connected in series, and the second superconducting switch includes a plurality of second superconducting quantum interference devices connected in series; wherein, The shielding parameter β corresponding to the loop inductance of the second superconducting quantum interference device L <<1.

4. The superconducting quantum interference circuit according to claim 2, characterized in that: The feedback polarity adjustment module comprises: A magnetic flux bias line is inductively coupled to each second superconducting quantum interference device of one of the first superconducting switch and the second superconducting switch; the magnetic flux bias line is used to provide a first bias current that generates a half-integer multiple of magnetic flux quanta with each second superconducting quantum interference device; A control current line is inductively coupled with each second superconducting quantum interference device of the first superconducting switch and each second superconducting quantum interference device of the second superconducting switch; the control current line is used to provide a first control current that generates an integer multiple of magnetic flux quanta with each second superconducting quantum interference device, or to provide a second control current that generates a half-integer multiple of magnetic flux quanta with each second superconducting quantum interference device.

5. The superconducting quantum interference circuit according to claim 2, characterized in that: The positive feedback circuit further includes a first resistor connected in series with the first inductor, and the negative feedback circuit further includes a second resistor connected in series with the second inductor; The first resistor and the second resistor are titanium / platinum double-layer metal.

6. The superconducting quantum interference circuit according to claim 5, characterized in that: The first superconducting quantum interference device, the first resistor, the first inductor coil and the first superconducting switch are connected by a superconducting wire; The first superconducting quantum interference device, the second resistor, the second inductor and the second superconducting switch are connected through a superconducting wire.

7. The superconducting quantum interference circuit according to any one of claims 2 to 6, characterized in that: The superconducting quantum interference circuit also includes: A current bias line connected to the first superconducting quantum interference device and used to provide a second bias current; the second bias current is used to drive the first superconducting quantum interference device to maintain a current bias mode; The second bias current is greater than a critical current of the first superconducting quantum interference device, and the second bias current is less than a critical current of the first superconducting switch and a critical current of the second superconducting switch.

8. The superconducting quantum interference circuit according to any one of claims 1 to 6, characterized in that: The first inductor coil and the second inductor coil are coiled metal niobium superconducting wires.

9. The superconducting quantum interference circuit according to any one of claims 1 to 6, characterized in that: The first superconducting quantum interference device is a direct current superconducting quantum interference device.

10. An integrated chip, characterized in that: The integrated chip comprises the superconducting quantum interference circuit according to any one of claims 1 to 9.

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