Microwave quantum frequency conversion circuit

Abstract

The invention provides a microwave quantum frequency conversion circuit which comprises at least two Josephson junction arrays, a plurality of direct-current output end leads are arranged between Josephson junctions of a first Josephson junction array of the first Josephson junction array, and when two of the direct-current output end leads are selected as direct-current output ends, the first Josephson junction array of the first Josephson junction array of the first Josephson junction array of the second Josephson junction array of the second Josephson junction array of the second Josephson junction array of the second the numbers of Josephson junctions included between the selected DC output ends are also different; a plurality of direct-current input end leads are arranged between Josephson junctions of the second Josephson junction array, and when two of the direct-current input end leads are selected as direct-current input ends, the number of the Josephson junctions included between the selected direct-current input ends is different; the first Josephson junction array outputs a voltage signal to the second Josephson junction array, so that precise frequency conversion of quantum precision of microwave signals can be realized, and the frequency conversion proportion can be changed through real-time control switching of a lead of the corresponding Josephson junction array by opening and closing an external circuit program.

Description

Technical Field

[0001] The present application relates to the technical field of integrated superconducting Josephson array circuit design, and in particular to a microwave quantum frequency conversion circuit. Background Art

[0002] Microwave converters are essential for frequency conversion in microwave systems, particularly in satellite testing, satellite ground stations, telemetry and remote control, radar, and complex electromagnetic environments. Microwave converters are typically used to convert input signals to the desired target frequency band. Depending on the frequency conversion process, they can be categorized as downconverters or upconverters. In some low-temperature applications, the use of separate downconverters and upconverters is severely limited in size and heat load.

[0003] Microwave sources based on superconducting Josephson junctions have inherent advantages for the above-mentioned low-temperature applications, as they have very low power dissipation.

[0004] The reported microwave source based on superconducting Josephson junction is based on the AC Josephson effect, that is, when a DC voltage is applied to both ends of the Josephson junction, an AC current signal will be radiated at both ends of the Josephson junction. The frequency of the signal is determined by the voltage. According to the Josephson formula, f = V dc ·(2e / h). Where e is the electron charge, V dc is the DC voltage applied to the Josephson junction, and h is Planck's constant. However, conventional constant voltage sources cannot achieve quantum flux (h / 2e, approximately 2.07×10 -15 The reported microwave sources based on superconducting Josephson junctions achieve signal resonance by embedding the Josephson junction in a microwave resonant cavity with extremely high quality parameters, so the adjustable range of the microwave source frequency is limited. Summary of the Invention

[0005] Based on this, a microwave quantum frequency conversion circuit is provided to solve the problem that the adjustable range of microwave source frequency is limited.

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

[0007] Two ends of the second Josephson junction array are microwave output ends. A plurality of DC input leads are provided between the Josephson junctions of the second Josephson junction array. When two of the DC input leads are selected as DC input ends, the number of Josephson junctions included between the selected DC input ends is also different.

[0008] The two DC output ends of the first Josephson junction array are connected to the two DC input ends of the second Josephson junction array through two filtering modules respectively. The first Josephson junction array outputs a voltage signal to the second Josephson junction array, so that the two microwave output ends of the second Josephson junction array output frequency-converted microwave signals.

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

[0010] Optionally, the first input end 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 filtering module, the first end of the first filtering module is connected to the DC output end of the first Josephson junction array, and the second end is connected to the DC input end of the second Josephson junction array; the second filtering module, the first end of the second filtering module is connected to the DC output end of the first Josephson junction array, and the second end is connected to the DC input end of the second Josephson junction array; the second end of the first filtering module is a positive DC output end; the second end of the second filtering module is a negative DC output end; the voltage between the positive DC output end and the negative DC output end is V dc =M(h / 2e)f1, where V dc is the voltage generated across M Josephson junctions, e is the electron charge, and h is Planck's constant.

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

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

[0013] Optionally, the microwave input end of the first Josephson junction array inputs microwaves 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 to the other ends 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 in sequence.

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

[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 precise frequency conversion of microwave signals with quantum precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings involved in the embodiments, which are part of the present invention. It should be pointed out that the exemplary embodiments and their related descriptions are only used to explain the technical content of the present invention and do not constitute any undue limitation of 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 DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0021] The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application include direct and indirect connections (couplings) unless otherwise specified. In the description of this application, it should be understood that the orientations or positional relationships indicated by the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to this application.

[0022] In this application, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

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

[0024] Two ends of the second Josephson junction array are microwave output ends. A plurality of DC input leads are provided between the Josephson junctions of the second Josephson junction array. When two of the DC input leads are selected as DC input ends, the number of Josephson junctions included between the selected DC input ends is also different.

[0025] The two DC output ends of the first Josephson junction array are connected to the two DC input ends of the second Josephson junction array through two filtering modules respectively. The first Josephson junction array outputs a voltage signal to the second Josephson junction array, so that the two microwave output ends of the second Josephson junction array output frequency-converted microwave signals.

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

[0027] In one embodiment, the first input end 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 filtering module, the first end of the first filtering module is connected to the DC output end of the first Josephson junction array, and the second end is connected to the DC input end of the second Josephson junction array; the second filtering module, the first end of the second filtering module is connected to the DC output end of the first Josephson junction array, and the second end is connected to the DC input end of the second Josephson junction array; the second end of the first filtering module is a positive DC output end; the second end of the second filtering module is a negative DC output end; the voltage between the positive DC output end and the negative DC output end is Vdc =M(h / 2e)f1, where V dc is the voltage generated at both ends of M Josephson junctions, e is the electron charge, and h is the Planck constant. Figure 1 In the embodiment shown, the DC output end of the first Josephson junction array and the DC input end of the second Josephson junction array can be respectively connected to the first filtering module, and similarly, another DC output end of the first Josephson junction array and another DC input end of the second Josephson junction array can be respectively connected to the second filtering module.

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

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

[0030] In one embodiment, the microwave input end of the first Josephson junction array is input with a microwave 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 to the other ends 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 a superconductor layer arranged in sequence.

[0032] In one embodiment, the Josephson junction includes a superconductor layer, a non-superconducting metal layer, and a superconductor layer arranged in sequence.

[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] According to the inverse effect of the AC Josephson effect, using a current bias and irradiating the Josephson junction with microwaves of frequency f will generate a constant voltage across the Josephson junction, called the "Shapino voltage step", with the formula V dc =(h / 2e)f. This effect is used to realize a voltage reference that can achieve quantum precision. Using a string of M series-connected Josephson junctions with an input frequency of f1, V dc =M(h / 2e)f1, a quantum-precise voltage applied to another string of N series-connected Josephson junctions yields a quantum-precise microwave signal with a frequency of f2 = (M / N)f1. From a macroscopic perspective, these two strings of junctions enable quantum-precise frequency conversion of microwave signals.

[0035] like Figure 1 As shown, a Josephson junction array 10 containing M serially connected Josephson junctions is used, and a microwave with a frequency of f1 or a pulse with a repetition frequency of f1 is input from one end to generate V dc =M(h / 2e)f1. When using microwaves, appropriate bias currents must be input to the Josephson array 10 from ports 1 and 2, but not when inputting pulses. Therefore, in this embodiment, a fifth filter module 15 and a sixth filter module 16 are connected to the two ends of the first Josephson junction array, respectively, and a DC current is input to the other ends of the fifth and sixth filter modules 15 and 16. When using microwaves, appropriate bias currents must 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-connected Josephson junctions yields a microwave signal with f2 = (M / N)f1. This achieves quantum-precision frequency conversion of microwave signals. Inputting appropriate DC currents to ports 3 and 4 facilitates the microwave signal of frequency f2 in 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 may be provided at each DC output lead of the first Josephson junction array, and a low-pass filter may be provided at each DC input lead of the second Josephson junction array.

[0036] The solution of the present application has extremely high frequency conversion accuracy and wide frequency conversion range, and can be used for both up-conversion and down-conversion, as well as multi-channel combination.

[0037] In this embodiment, each of the Josephson junctions may be composed of two weakly connected superconductors, and the weakly connected structure may be a thin insulating layer, forming a superconductor-insulator-superconductor structure (ie, SIS structure).

[0038] The Josephson junction can also consist of two superconductors that are weakly connected to each other, where the weak connection can be a small section of non-superconducting metal, forming an SNS structure. The Josephson junction can also consist of two superconductors that are weakly connected to each other, where the superconductivity is weakened in a narrow section at the contact point, forming an SsS structure.

[0039] While the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to these specific embodiments. The above embodiments are merely illustrative and non-restrictive. Those skilled in the art will appreciate that various modifications may be made based on the teachings of the present invention without departing from the scope of protection of the present invention and the claims, and such modifications shall be deemed to be within the scope of protection of the present invention.

Claims

1. A microwave quantum frequency conversion circuit, characterized in that: The invention comprises at least two Josephson junction arrays, wherein one end of the first Josephson junction array is a microwave input end for inputting microwave signals, and the other end is connected to a terminal resistor. A plurality of DC output leads are provided between the Josephson junctions of the first Josephson junction array. When two of the DC output leads are selected as DC output ends, the number of Josephson junctions included between the selected DC output ends is also different. Two ends of the second Josephson junction array are microwave output ends. A plurality of DC input leads are provided between the Josephson junctions of the second Josephson junction array. When two of the DC input leads are selected as DC input ends, the number of Josephson junctions included between the selected DC input ends is also different. The two DC output ends of the first Josephson junction array are connected to the two DC input ends of the second Josephson junction array through two filtering modules respectively. The first Josephson junction array outputs a voltage signal to the second Josephson junction array, so that the two microwave output ends 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 includes M serially connected Josephson junctions between the two DC output terminals; the second Josephson junction array includes N serially connected Josephson junctions between the two DC input terminals.

3. The microwave quantum frequency conversion circuit according to claim 2, characterized in that: The first input end 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 filtering module, wherein the first end of the first filtering module is connected to the DC output end of the first Josephson junction array, and the second end is connected to the DC input end of the second Josephson junction array; a second filtering module, wherein the first end of the second filtering module is connected to the DC output end of the first Josephson junction array, and the second end is connected to the DC input end of the second Josephson junction array; the second end of the first filtering module is a positive DC output end; the second end of the second filtering module is a negative DC output end; the voltage between the positive DC output end and the negative DC output end is V dc =M(h / 2e)f1, where V dc is the voltage generated across M Josephson junctions, e is the electron charge, and h is Planck's constant.

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

5. The microwave quantum frequency conversion circuit according to claim 3, characterized in that: Two ends of the second Josephson junction array are respectively connected to a third filter module and a fourth filter module, and a direct current is input to the other ends 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 end of the first Josephson junction array inputs microwaves with a frequency of f1. 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 to the other ends 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 includes a superconductor layer, an insulator layer and a superconductor layer which are arranged in sequence.

8. The microwave quantum frequency conversion circuit according to claim 1, characterized in that: The Josephson junction includes a superconductor layer, a non-superconducting metal layer and a superconductor layer which are arranged in sequence.

9. The microwave quantum frequency conversion circuit according to any one of claims 3, 5 or 6, characterized in that: 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.

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 lead of the first Josephson junction array and the input lead of the second Josephson junction array through an external circuit program, and the output end is controlled to switch between the output end leads in real time, and the input end is controlled to switch between the input end leads in real time.

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