Test probe for DC quantum small voltage

Abstract

This invention discloses a test probe for DC quantum small voltage. The test probe includes a main body, a first microwave adapter, a second microwave adapter, and two waveguides. The main body includes a first end and a second end disposed opposite to each other; the first microwave adapter is disposed at the first end of the main body; the second microwave adapter is disposed at the second end of the main body; both waveguides extend from the first end to the second end of the main body to transmit two different microwave drive signals, and the two ends of each waveguide are respectively connected to the first microwave adapter and the second microwave adapter. The test probe of this invention employs a dual-channel microwave transmission link, enabling frequency differential drive. When this test probe is combined with bias current drive control technology to simultaneously drive two Josephson superconducting array junctions, precise nanovolt-level DC quantum small voltage output can be achieved, which can be applied to the calibration of digital nanovoltmeters and the resolution testing of high-accuracy digital voltmeters.

Description

Technical Field

[0001] This invention relates to the field of test probe technology, and more specifically, to a test probe for DC quantum small voltage. Background Technology

[0002] The test probe is an important component of superconducting voltage labeling. During the testing process, the test probe is responsible for introducing the superconducting voltage from the low-temperature environment to room temperature through the low-temperature connection lead for testing.

[0003] Previously, Josephson superconducting array junctions driven by probes used for DC quantum voltage testing could only achieve DC quantum voltage output at relatively high voltages (145μV to 10V), and could not achieve voltage output at lower voltages (below 145μV). Summary of the Invention

[0004] The main objective of this invention is to provide a test probe for DC quantum voltage, which solves the problem that Josephson superconducting array junctions driven by previous test probes for DC quantum voltage cannot achieve low voltage output.

[0005] To achieve the above objectives, the present invention provides a test probe for DC quantum small voltage, comprising:

[0006] The main body includes a first end and a second end disposed opposite to each other;

[0007] A first microwave adapter is used to connect to the output interface of a microwave source, and the first microwave adapter is disposed at the first end of the main body.

[0008] A second microwave adapter, used for connection to a superconducting array junction interface, is disposed at the second end of the main body; and

[0009] Two waveguides extend from the first end to the second end of the main body to transmit two different microwave drive signals, and the two ends of each waveguide are respectively connected to the first microwave adapter and the second microwave adapter.

[0010] Furthermore, the first microwave adapter includes a first microwave source inlet and a second microwave source inlet, and the second microwave adapter includes a first superconducting array junction interface and a second superconducting array junction interface.

[0011] The two waveguides are a first waveguide and a second waveguide. The first waveguide is connected between the first microwave source inlet and the first superconducting array junction interface, and the second waveguide is connected between the second microwave source inlet and the second superconducting array junction interface.

[0012] Furthermore, the main body includes:

[0013] A connecting rod having a first end and a second end disposed opposite to each other, the first end forming the second end of the main body portion;

[0014] An adapter box is disposed at the second end of the connecting rod, and the end of the adapter box away from the connecting rod forms the first end of the main body.

[0015] Both of the waveguides extend along the interior of the connecting rod and the adapter box.

[0016] Furthermore, the connecting rod is a stainless steel rod.

[0017] Furthermore, the adapter box is equipped with a voltage output connector.

[0018] Furthermore, the test probe for DC quantum small voltage also includes a shielding structure, which is disposed at the second end of the main body, and the second microwave adapter is disposed inside the shielding structure.

[0019] Furthermore, the shielding structure is a shielding sleeve, which is threaded onto the second end of the main body.

[0020] When applying the technical solution of this invention, the first microwave adapter is connected to the output interface of the microwave source, and the second microwave adapter is connected to the connection interface of the superconducting array junction. Then, a specific microwave frequency and microwave power are provided to the superconducting array junction through the microwave source and waveguides, thereby realizing the microwave conditions for the Josephson effect. Since the test probe in this invention has two waveguides, these two waveguides can be used to transmit two different microwave signals. In use, the frequency difference value of the two microwave drive sources can be calculated and determined according to the required quantum voltage nominal value. Then, the microwave source is adjusted so that the two waveguides output different frequencies of microwave drive signals. That is to say, the test probe of this invention uses a dual-channel microwave transmission link, which can realize frequency differential drive. When this test probe is combined with bias current drive control technology to simultaneously drive two Josephson superconducting array junctions, a precise nanovolt-level DC quantum voltage output can be achieved. This can be applied to the calibration of digital nanovoltmeters and the resolution testing of high-accuracy digital voltmeters. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0022] Figure 1 This is a schematic diagram of the structure of a test probe for DC quantum small voltage disclosed in an embodiment of the present invention.

[0023] The above figures include the following reference numerals:

[0024] 10. Main body; 101. First end; 102. Second end; 11. Connecting rod; 111. First end; 112. Second end; 12. Adapter box; 122. Voltage output connector; 20. First microwave adapter; 21. First microwave source inlet; 22. Second microwave source inlet; 30. Second microwave adapter; 31. First superconducting array junction interface; 32. Second superconducting array junction interface; 40. Waveguide; 41. First waveguide; 42. Second waveguide; 50. Shielding structure. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0027] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0028] Through long-term research, the inventors discovered that a single-channel Josephson superconducting array junction driven by a test probe can only achieve a relatively large DC quantum voltage output, and cannot achieve DC quantum voltage values ​​below 145μV. Therefore, the inventors designed a driving method for nanovolt-level DC quantum voltages, which includes three steps: step S1, step S2, and step S3.

[0029] Step S1: Simultaneously drive two Josephson array junctions using a two-way microwave driver source combined with a two-way bias current driver source control technique. It can be understood that this means that the microwave driver source, the bias current driver source, and the Josephson array junctions are all dual-path. In actual driving, the first microwave driver source and the first bias current driver source are used to drive the first Josephson array junction, while the second microwave driver source and the second bias current driver source are used to drive the second Josephson array junction.

[0030] Step S2: Obtain the nominal value V of the DC quantum small voltage and the number of quantum voltage steps n of the superconducting junction. Simultaneously, change the frequency of the microwave driving signal applied to the two Josephson array junctions and the number of superconducting array junctions of the bias current driving source to generate two quantum DC voltage signals, which are recorded as V1 and V2 respectively, where V1 = N1*nf1 / K J V2 = N2 * nf2 / K J V1 is the first quantum DC voltage signal, V2 is the second quantum DC voltage signal, N1 is the number of first superconducting junctions, N2 is the number of second superconducting junctions, n is the number of quantum voltage steps of the superconducting junction, f1 is the frequency of the first microwave source, f2 is the frequency of the second microwave source, and K... J is the Josephson constant.

[0031] In this step, the number of quantum voltage steps n of the superconducting junction is generally taken as the first step in practical applications, therefore n is taken as 1, K J K is the Josephson constant. According to Resolution 1 of the 26th General Conference on Weights and Measures, after May 20, 2019, the Josephson constant K is... J =483597.848416984GHz / V.

[0032] Step S3: Based on the frequency of the microwave drive signal applied to the two Josephson array junctions and the number of superconducting array junctions of the bias current drive source, use the formula V'=V1-V2=N1*nf1 / K J -N2*nf2 / K J = (N1f1–N2f2)*n / K JThe nanovolt-level DC quantum voltage signal V' can then be calculated. In step S3, N1 = N2.

[0033] The driving method of the present invention will be described below with specific examples:

[0034] Taking a 100nV DC quantum voltage output as an example, firstly, two microwave drive sources combined with two bias current drive sources are used to simultaneously drive two Josephson array junctions. Then, based on the required nominal quantum voltage value V = 100nV, N1 = N2 = 1, n = 1, and according to the formula Δf = f1 – f2 = V * K, J =48.36MHz, meaning that to obtain a nominal DC quantum voltage of 100nV, the two Josephson superconducting array junctions of the bias current drive source need to have the same number, and the frequency difference between the two microwave drive signals needs to be adjusted to 48.36MHz. In other words, by changing the number of Josephson superconducting array junctions driven by the two channels and appropriately adjusting the frequency difference between the two microwave drive signals, a precise quantum DC voltage signal of 100nV to 1mV can be obtained.

[0035] To implement the aforementioned driving method for nanovolt-level DC quantum small voltages, the inventors also designed a test probe for DC quantum small voltages. See [link to relevant documentation]. Figure 1 As shown, the test probe for DC quantum small voltage includes a main body 10, a first microwave adapter 20, a second microwave adapter 30, and two waveguides 40.

[0036] The main body 10 includes a first end 101 and a second end 102 disposed opposite to each other. A first microwave adapter 20 is used to connect to the output interface of a microwave source and is disposed at the first end 101 of the main body 10. A second microwave adapter 30 is used to connect to the connection interface of a superconducting array junction and is disposed at the second end 102 of the main body 10. Two waveguides 40 extend along the direction from the first end 101 to the second end 102 of the main body 10 to transmit two different microwave signals. The waveguides 40 can realize the transmission of microwave signals from room temperature to low temperature within the main body 10, and the two ends of each waveguide 40 are respectively connected to the first microwave adapter 20 and the second microwave adapter 30.

[0037] In this embodiment:

[0038] The first microwave adapter 20 is the output interface of the microwave source, which is connected to the output ports of the two microwave sources respectively.

[0039] The second microwave adapter 30 is a connection interface for the superconducting array junction. It can connect to the input ports of two programmable Josephson superconducting array junctions respectively. The microwave source provides the programmable Josephson superconducting array junction with a specific microwave frequency and microwave power, thereby realizing the microwave conditions for the programmable Josephson superconducting array junction to generate the Josephson effect.

[0040] Waveguide 40 enables the transmission of microwave signals from the microwave source output from room temperature to low temperature, from the microwave source input to the programmable Josephson superconducting array junction.

[0041] When using the test probe for DC quantum small voltage of the present invention, the first microwave adapter 20 is connected to the output interface of the microwave source, and the second microwave adapter 30 is connected to the connection interface of the superconducting array junction. Then, the microwave source and waveguide 40 provide the superconducting array junction with specific microwave frequency and microwave power, thereby realizing the microwave conditions of the Josephson effect. Since the test probe of the present invention has two waveguides 40, these two waveguides 40 can be used to transmit two different microwave signals. In use, the frequency difference value of the two microwave driving sources can be determined according to the driving method for nanovolt-level DC quantum small voltage, and then the microwave source can be adjusted so that the two waveguides 40 output different frequencies of microwave driving signals. That is to say, the test probe of the present invention uses a dual-channel microwave transmission link, which can realize frequency differential driving. When the test probe is combined with bias current driving control technology to simultaneously drive two Josephson superconducting array junctions, accurate nanovolt-level DC quantum small voltage output can be achieved, which can be applied to the calibration of digital nanovoltmeters and the resolution testing of high-accuracy digital voltmeters.

[0042] Specifically, the main body 10 in this embodiment includes a connecting rod 11 and an adapter box 12. The connecting rod 11 can be a cylindrical rod structure, a prismatic rod structure, or other irregularly shaped rod structures. Optionally, the connecting rod 11 is made of stainless steel, which has high strength and a long service life. The connecting rod 11 has a first end 111 and a second end 112 disposed opposite to each other. The first end 111 forms the second end 102 of the main body 10. The adapter box 12 is disposed at the second end 112 of the connecting rod 11, and the end of the adapter box 12 away from the connecting rod 11 forms the first end 101 of the main body 10. When actually assembling the test probe in this embodiment, the adapter box 12 can be fixed to the second end 112 of the connecting rod 111 by welding, snap-fitting, or locking screws. Both of the aforementioned waveguides 40 extend along the interior of the connecting rod 11 and the adapter box 12. The adapter box 12 and the connecting rod 11 enable the transition of microwave signals from the normal temperature range to the low temperature range, and provide fixed support for the first microwave adapter 20, the second microwave adapter 30, and the waveguide 40.

[0043] Furthermore, in this embodiment, the adapter box 12 is a measurement adapter box, and the adapter box 12 is provided with a voltage output connector 121 to facilitate the output voltage of the Josephson superconducting array junction.

[0044] Furthermore, in this embodiment, the first microwave adapter 20 includes a first microwave source inlet 21 and a second microwave source inlet 22, and the second microwave adapter 30 includes a first superconducting array junction interface 31 and a second superconducting array junction interface 32. For ease of distinction, the two waveguides 40 are respectively labeled as the first waveguide 41 and the second waveguide 42. In actual connection, the first waveguide 41 is connected between the first microwave source inlet 21 and the first superconducting array junction interface 31 to transmit microwave drive signals to one superconducting array junction, and the second waveguide 42 is connected between the second microwave source inlet 22 and the second superconducting array junction interface 32 to transmit microwave drive signals to another superconducting array junction. At this point, by adjusting the two microwave sources to make the two waveguides 40 output different frequencies of microwave drive signals, frequency differential drive can be achieved. When the test probe is combined with bias current drive control technology to drive the two Josephson superconducting array junctions simultaneously, precise nanovolt-level DC quantum small voltage output can be achieved, which can be applied to the calibration of digital nanovoltmeters and the resolution test of high-accuracy digital voltmeters.

[0045] See you again Figure 1 As shown, the test probe in this embodiment also includes a shielding structure 50, which is disposed at the second end 102 of the main body 10. The second microwave adapter 30 is disposed inside the shielding structure 50. Through the function of the shielding structure 50, external signals can be prevented from interfering with the system where the test probe is located.

[0046] Optionally, the shielding structure 50 in this embodiment is a shielding sleeve, which is threaded onto the second end 102 of the main body 10. This structure is simple and easy to implement. Of course, in other embodiments of the present invention, the shielding structure 50 can also be connected to the second end 102 of the main body 10 by welding, snap-fitting, or other methods. Any other modifications within the scope of the present invention are within the protection range of the present invention.

[0047] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0048] This invention enables the transmission of dual-channel microwave drive signals from room temperature to the liquid helium temperature range. It allows for the simultaneous driving of two programmable Josephson superconducting array junctions within the same cryogenic system, thereby achieving precise nanovolt-level DC quantum voltage output. By varying the frequency of the microwave drive signals applied to the two Josephson superconducting array junctions and the number of superconducting array junctions driven by the bias current, precise nanovolt-level DC quantum voltage signals can be obtained.

[0049] In other words, the test probe of this invention uses a dual-channel microwave transmission link to achieve simultaneous driving of two Josephson superconducting array junctions using frequency differential drive combined with bias current drive control technology, thereby achieving precise nanovolt-level DC quantum small voltage output. It can be applied to the calibration of digital nanovoltmeters and the resolution test of high-accuracy digital voltmeters.

[0050] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components in this application is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0051] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A test probe for DC quantum voltage, used to achieve DC quantum voltage measurement below 145μV, characterized in that, include: The main body (10) includes a first end (101) and a second end (102) disposed opposite to each other. The first microwave adapter (20) is used to connect to the output interface of the microwave source and is disposed at the first end (101) of the main body (10). A second microwave adapter (30) is used to connect to the connection interface of a superconducting array junction, and the second microwave adapter (30) is disposed at the second end (102) of the main body (10); and Two waveguides (40) are provided, both of which extend along the direction from the first end (101) to the second end (102) of the main body (10) to transmit two microwave drive signals of different frequencies, and the two ends of each waveguide (40) are respectively connected to the first microwave adapter (20) and the second microwave adapter (30). The first microwave adapter (20) includes a first microwave source inlet (21) and a second microwave source inlet (22), and the second microwave adapter (30) includes a first superconducting array junction interface (31) and a second superconducting array junction interface (32). The two waveguides (40) are a first waveguide (41) and a second waveguide (42), respectively. The first waveguide (41) is connected between the first microwave source inlet (21) and the first superconducting array junction interface (31), and the second waveguide (42) is connected between the second microwave source inlet (22) and the second superconducting array junction interface (32). The test probe uses a dual-channel microwave transmission link to achieve frequency differential drive. The test probe combines bias current drive control technology to drive two Josephson superconducting array junctions simultaneously. Based on the frequency of the microwave drive signal applied to the two Josephson array junctions and the number of superconducting array junctions of the bias current drive source, the difference between the two quantum DC voltage signals is used to obtain the nanovolt-level DC quantum small voltage signal.

2. The test probe for DC quantum small voltage according to claim 1, characterized in that, The main body (10) includes: The connecting rod (11) has a first end (111) and a second end (112) disposed opposite to each other, and the first end (111) forms the second end (102) of the main body (10). The adapter box (12) is disposed at the second end (112) of the connecting rod (11), and the end of the adapter box (12) away from the connecting rod (11) forms the first end (101) of the main body (10). Both of the waveguides (40) extend along the interior of the connecting rod (11) and the adapter box (12).

3. The test probe for DC quantum small voltage according to claim 2, characterized in that, The connecting rod (11) is a stainless steel rod.

4. The test probe for DC quantum small voltage according to claim 2, characterized in that, The adapter box (12) is provided with a voltage output connector (122).

5. The test probe for DC quantum small voltage according to claim 1, characterized in that, The test probe for DC quantum small voltage also includes a shielding structure (50), which is disposed at the second end (102) of the main body (10), and the second microwave adapter (30) is disposed inside the shielding structure (50).

6. The test probe for DC quantum small voltage according to claim 5, characterized in that, The shielding structure (50) is a shielding sleeve, which is threaded onto the second end (102) of the main body (10).

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