A microwave quantum frequency conversion circuit

Abstract

This application provides a microwave quantum frequency conversion circuit, including at least two Josephson junction arrays. A first Josephson junction array has several DC output leads between its Josephson junctions. When two of these leads are selected as DC output terminals, the number of Josephson junctions between them varies. A second Josephson junction array has several DC input leads between its Josephson junctions. When two of these leads are selected as DC input terminals, the number of Josephson junctions between them also varies. The first Josephson junction array outputs a voltage signal to the second Josephson junction array, enabling precise frequency conversion of the microwave signal with quantum precision. The frequency conversion ratio can be changed in real-time by switching the corresponding Josephson junction array leads on and off via an external circuit program.

Description

Technical Field

[0001] This application relates to the field of integrated superconducting Josephson array circuit design technology, and in particular to a microwave quantum frequency conversion circuit. Background Technology

[0002] Microwave frequency converters are indispensable in microwave systems where frequency conversion is frequently used, such as in satellite testing, satellite ground stations, telemetry and remote control, radar, and complex electromagnetic environments. Microwave frequency converters are essential instruments in these applications. They are typically used to convert input signals to the desired target frequency band and can be categorized as down-converters and up-converters based on the conditions before and after frequency conversion. In some low-temperature applications, using separate down-converters and up-converters is severely limited in terms of size and thermal load.

[0003] Microwave sources based on superconducting Josephson junctions have an inherent advantage for the aforementioned low-temperature applications, as they exhibit very low power dissipation.

[0004] The reported microwave sources based on superconducting Josephson junctions are based on the alternating Josephson effect. That is, when a DC voltage is applied across the Josephson junction, an alternating current signal is radiated across the junction. The frequency of the signal is determined by the voltage, and according to the Josephson formula: f = V dc ·(2e / h). Where e is the electron charge, V dc Let h be the DC voltage applied across the Josephson junction, and h be Planck's constant. However, conventional constant voltage sources cannot achieve quantum magnetic flux (h / 2e, approximately 2.07 × 10⁻⁶). -15 To control the accuracy of Wb), reported microwave sources based on superconducting Josephson junctions achieve signal resonance by nesting the Josephson junction in a microwave resonant cavity with extremely high quality parameters, thus limiting the adjustable range of the microwave source frequency. Summary of the Invention

[0005] To address the limitation of the adjustable frequency range of microwave sources, a microwave quantum frequency conversion circuit is provided.

[0006] This application provides a microwave quantum frequency conversion circuit, including at least two Josephson junction arrays, wherein one end of the first Josephson junction array is a microwave input terminal for inputting microwave signals, and the other end is connected to a terminating resistor. A plurality of DC output terminal leads are arranged between the Josephson junctions of the first Josephson junction array. When two of the DC output terminal leads are selected as DC output terminals, the number of Josephson junctions included between the selected DC output terminals is also different.

[0007] The two ends of the second Josephson junction array are microwave output terminals. Several DC input terminals are arranged between the Josephson junctions of the second Josephson junction array. When two DC input terminals are selected as DC input terminals, the number of Josephson junctions between the selected DC input terminals is also different.

[0008] The two DC output terminals of the first Josephson junction array are connected to the two DC input terminals of the second Josephson junction array through two filter modules. The first Josephson junction array outputs a voltage signal to the second Josephson junction array, thereby the two microwave output terminals of the second Josephson junction array output frequency-converted microwave signals.

[0009] Optionally, the first Josephson junction array includes M series-connected Josephson junctions between its two DC output terminals; the second Josephson junction array includes N series-connected Josephson junctions between its two DC input terminals.

[0010] Optionally, the first input terminal of the first Josephson junction array is a microwave with a frequency of f1 or a pulse with a repetition frequency of f1; the first filter module has its first terminal connected to the DC output terminal of the first Josephson junction array and its second terminal connected to the DC input terminal of the second Josephson junction array; the second filter module has its first terminal connected to the DC output terminal of the first Josephson junction array and its second terminal connected to the DC input terminal of the second Josephson junction array; the second terminal of the first filter module is a positive DC output terminal; the second terminal of the second filter module is a negative DC output terminal; the voltage between the positive DC output terminal and the negative DC output terminal is V. dc =M(h / 2e)f1, where, V dc Let e ​​be the voltage across the M Josephson junctions, e be the electron charge, and h be Planck's constant.

[0011] Optionally, the two ends of the second Josephson junction array are connected to microwave output terminals; the output microwave signal frequency is f2 = (M / N)f1.

[0012] Optionally, a third filter module and a fourth filter module are connected to the two ends of the second Josephson junction array, respectively, and a DC current is input to the other end of the third filter module and the fourth filter module.

[0013] Optionally, the microwave input terminal of the first Josephson junction array is a microwave with a frequency of f1, and the two ends of the first Josephson junction array are respectively connected to a fifth filter module and a sixth filter module, and a DC current is input at the other end of the fifth filter module and the sixth filter module.

[0014] Optionally, the Josephson junction includes a superconductor layer, an insulator layer, and a superconductor layer arranged sequentially.

[0015] Optionally, the Josephson junction includes a superconducting layer, a non-superconducting metal layer, and a superconducting layer arranged sequentially.

[0016] Optionally, the first filtering module, the second filtering module, the third filtering module, the fourth filtering module, the fifth filtering module, and the sixth filtering module are low-pass filters.

[0017] The technical solution adopted in this application can achieve quantum precision frequency conversion of microwave signals. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings involved in the embodiments will be briefly described below. These drawings are part of the present invention. It should be noted that the illustrative embodiments and their related descriptions are only used to explain the technical content of the present invention and do not constitute any improper limitation on the present invention. In the drawings:

[0019] Figure 1 This is a schematic diagram of the microwave quantum frequency conversion circuit of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0021] The serial numbers assigned to components in this document, such as "first" and "second," are used solely to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages). It should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are used solely for the convenience of describing this application and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0022] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0023] Please see Figure 1 This application provides a microwave quantum frequency conversion circuit, including at least two Josephson junction arrays, wherein one end of the first Josephson junction array is a microwave input terminal for inputting microwave signals, and the other end is connected to a terminating resistor. A plurality of DC output terminal leads are arranged between the Josephson junctions of the first Josephson junction array. When two of the DC output terminal leads are selected as DC output terminals, the number of Josephson junctions included between the selected DC output terminals is also different.

[0024] The two ends of the second Josephson junction array are microwave output terminals. Several DC input terminals are arranged between the Josephson junctions of the second Josephson junction array. When two DC input terminals are selected as DC input terminals, the number of Josephson junctions between the selected DC input terminals is also different.

[0025] The two DC output terminals of the first Josephson junction array are connected to the two DC input terminals of the second Josephson junction array through two filter modules. The first Josephson junction array outputs a voltage signal to the second Josephson junction array, thereby the two microwave output terminals of the second Josephson junction array output frequency-converted microwave signals.

[0026] In one embodiment, the first Josephson junction array includes M series-connected Josephson junctions between its two DC output terminals; the second Josephson junction array includes N series-connected Josephson junctions between its two DC input terminals.

[0027] In one embodiment, the first input terminal of the first Josephson junction array is a microwave with a frequency of f1 or a pulse with a repetition frequency of f1; a first filter module has its first terminal connected to the DC output terminal of the first Josephson junction array and its second terminal connected to the DC input terminal of the second Josephson junction array; a second filter module has its first terminal connected to the DC output terminal of the first Josephson junction array and its second terminal connected to the DC input terminal of the second Josephson junction array; the second terminal of the first filter module is a positive DC output terminal; the second terminal of the second filter module is a negative DC output terminal; the voltage between the positive DC output terminal and the negative DC output terminal is V.dc =M(h / 2e)f1, where, V dc Let be the voltage across M Josephson junctions, e be the electron charge, and h be Planck's constant. Figure 1 In the illustrated embodiment, the DC output terminal of the first Josephson junction array and the DC input terminal of the second Josephson junction array can be connected to the first filter module respectively, and similarly, the other DC output terminal of the first Josephson junction array and the other DC input terminal of the second Josephson junction array can be connected to the second filter module respectively.

[0028] In one embodiment, the two ends of the second Josephson junction array are connected to microwave output terminals; the output microwave signal frequency is f2 = (M / N)f1.

[0029] In one embodiment, a third filter module and a fourth filter module are respectively connected to the two ends of the second Josephson junction array, and a DC current is input to the other end of the third filter module and the fourth filter module.

[0030] In one embodiment, the microwave input terminal of the first Josephson junction array is a microwave with a frequency of f1, and the two ends of the first Josephson junction array are respectively connected to a fifth filter module and a sixth filter module, and a DC current is input at the other end of the fifth filter module and the sixth filter module.

[0031] In one embodiment, the Josephson junction includes a superconductor layer, an insulator layer, and another superconductor layer arranged sequentially.

[0032] In one embodiment, the Josephson junction includes a superconducting layer, a non-superconducting metal layer, and a superconducting layer disposed sequentially.

[0033] In one embodiment, the first filtering module, the second filtering module, the third filtering module, the fourth filtering module, the fifth filtering module, and the sixth filtering module are low-pass filters.

[0034] Based on the inverse of the alternating Josephson effect, by biasing with current and radiating the Josephson junction with microwaves of frequency f, a constant voltage, known as the "Shapino voltage step," is generated across the Josephson junction, expressed as V. dc = (h / 2e)f. This effect is used to achieve a voltage reference with quantum precision. A voltage V can be generated using a junction array containing M cascaded Josephson junctions with an input frequency of f1. dc A quantum-precision voltage of M(h / 2e)f1 can be applied to another array of N series Josephson junctions to obtain a quantum-precision microwave signal with frequency f2 = (M / N)f1. From a macroscopic perspective, this arrangement of two arrays allows for precise quantum-precision frequency conversion of microwave signals.

[0035] like Figure 1 As shown, using a Josephson junction array 10 containing M series Josephson junctions, a microwave with a frequency of f1 or a pulse with a repetition frequency of f1 input from one end can generate V. dc The voltage = M(h / 2e)f1 requires a suitable bias current to be input to the Josephson array 10 from ports 1 and 2 when using microwaves, but not when inputting pulses. Therefore, in this embodiment, the first Josephson junction array is also connected to the fifth filter module 15 and the sixth filter module 16 respectively, and a DC current is input to the other end of the fifth filter module 15 and the sixth filter module 16. When using microwaves, a suitable bias current needs to be input to the first Josephson junction array from ports 1 and 2, but not when inputting pulses. Applying this voltage to another Josephson junction array 20 containing N series Josephson junctions can obtain a microwave signal f2 = (M / N)f1. This achieves quantum precision frequency conversion of the microwave signal. Inputting a suitable DC current at ports 3 and 4 is beneficial to the microwave signal with frequency f2 of the Josephson junction array 20. The first low-pass filter module 11, the second low-pass filter module 12, the third low-pass filter module 13, the fourth low-pass filter module 14, the fifth low-pass filter module 15, and the sixth low-pass filter module 16 are designed to prevent microwave or pulse signals with frequencies f1 and f2 from flowing out of their originally designed propagation paths from the branches. In another embodiment, a low-pass filter can also be provided at each DC output lead of the first Josephson junction array, and similarly, a low-pass filter can be provided at each DC input lead of the second Josephson junction array.

[0036] The proposed solution offers extremely high frequency conversion accuracy and a wide frequency conversion range, supporting both up-conversion and down-conversion, as well as multi-channel combinations.

[0037] In this embodiment, each Josephson junction may consist of two weakly interconnected superconductors. The weak interconnection may be a thin insulating layer, forming a superconductor-insulator-superconductor structure (i.e., SIS structure).

[0038] The Josephson junction can also be composed of two weakly connected superconductors. The weak connection can be a short segment of non-superconducting metal, forming an SNS structure. Alternatively, the Josephson junction can be composed of two weakly connected superconductors, which can weaken the superconductivity of the narrow portion at the contact point, forming what is abbreviated as SsS structure.

[0039] The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to these specific embodiments. The above embodiments are merely illustrative and not restrictive. For those skilled in the art, various modifications can be made under the guidance of the present invention without departing from the spirit and scope of protection of the claims, and all such modifications should be considered within the scope of protection of the present invention.

Claims

1. A microwave quantum frequency conversion circuit, characterized in that: It includes at least two Josephson junction arrays, wherein one end of the first Josephson junction array is a microwave input terminal for inputting microwave signals, and the other end is connected to a terminating resistor. Several DC output terminal leads are arranged between the Josephson junctions of the first Josephson junction array. When two DC output terminal leads are selected as DC output terminals, the number of Josephson junctions included between the selected DC output terminals is also different. The two ends of the second Josephson junction array are microwave output terminals. Several DC input terminals are arranged between the Josephson junctions of the second Josephson junction array. When two DC input terminals are selected as DC input terminals, the number of Josephson junctions between the selected DC input terminals is also different. The two DC output terminals of the first Josephson junction array are connected to the two DC input terminals of the second Josephson junction array through two filter modules. The first Josephson junction array outputs a voltage signal to the second Josephson junction array, thereby the two microwave output terminals of the second Josephson junction array output frequency-converted microwave signals.

2. The microwave quantum frequency conversion circuit according to claim 1, characterized in that, The first Josephson junction array has M series-connected Josephson junctions between its two DC output terminals; the second Josephson junction array has N series-connected Josephson junctions between its two DC input terminals.

3. The microwave quantum frequency conversion circuit according to claim 2, characterized in that, The first input terminal of the first Josephson junction array is a microwave with a frequency of f1 or a pulse with a repetition frequency of f1; the first filter module has its first terminal connected to the DC output terminal of the first Josephson junction array and its second terminal connected to the DC input terminal of the second Josephson junction array; the second filter module has its first terminal connected to the DC output terminal of the first Josephson junction array and its second terminal connected to the DC input terminal of the second Josephson junction array; the second terminal of the first filter module is a positive DC output terminal; the second terminal of the second filter module is a negative DC output terminal; the voltage between the positive DC output terminal and the negative DC output terminal is V. dc =M(h / 2e)f1, where, V dc Let e ​​be the voltage across the M Josephson junctions, e be the electron charge, and h be Planck's constant.

4. The microwave quantum frequency conversion circuit according to claim 3, characterized in that, The two ends of the second Josephson junction array are connected to microwave output terminals; The output microwave signal frequency is f2 = (M / N)f1.

5. The microwave quantum frequency conversion circuit according to claim 3, characterized in that, The second Josephson junction array is also connected to a third filter module and a fourth filter module at its two ends, respectively, and DC current is input at the other end of the third filter module and the fourth filter module.

6. The microwave quantum frequency conversion circuit according to claim 3, characterized in that, The microwave input terminal of the first Josephson junction array is a microwave with a frequency of f1. The two ends of the first Josephson junction array are respectively connected to the fifth filter module and the sixth filter module, and DC current is input at the other end of the fifth filter module and the sixth filter module.

7. The microwave quantum frequency conversion circuit according to claim 1, characterized in that, The Josephson junction comprises a superconductor layer, an insulator layer, and another superconductor layer arranged sequentially.

8. The microwave quantum frequency conversion circuit according to claim 1, characterized in that, The Josephson junction comprises a superconducting layer, a non-superconducting metal layer, and a superconducting layer arranged sequentially.

9. The microwave quantum frequency conversion circuit according to any one of claims 3, 5, or 6, characterized in that, The first, second, third, fourth, fifth, and sixth filtering modules are low-pass filters.

10. The microwave quantum frequency conversion circuit according to claim 1, characterized in that, The frequency conversion ratio is adjusted by opening and closing the corresponding output leads of the first Josephson array and the input leads of the second Josephson array through an external circuit program, thereby controlling the switching of the output leads between the output leads and the switching of the input leads between the input leads in real time.

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