Device based on anomalous Josephson effect, its preparation and phase control method

Abstract

The present invention provides a device based on the anomalous Josephson effect. The device based on the anomalous Josephson effect includes, from bottom to top, a substrate, a nanosheet, a Josephson N-junction layer (N is an integer ≥ 3), a first metal film, an insulating layer, a detection electrode layer, and a second metal film, and also provides a preparation method and a phase control method thereof. The device based on the anomalous Josephson effect of the present invention uses the anomalous Josephson effect to control the phase difference of the junction region, thereby enriching the means of controlling the phase difference of the junction region, and can also completely control all phase differences of the Josephson multi-junction, which is helpful for the future control and reading of topological quantum bits.

Description

Technical Field

[0001] The present invention belongs to the field of topological quantum computing, and specifically relates to a device based on the anomalous Josephson effect, and a method for preparing and controlling the phase of the device. Background Art

[0002] With the development of micro-nano technology, the size of integrated chips is getting smaller and smaller, and is getting closer and closer to the quantum limit. This also means that traditional semiconductor chips will be affected by quantum effects and fail. Therefore, the development of quantum computing will likely break this limitation. At the same time, due to its parallel computing capabilities, it is also expected to obtain computing capabilities that are difficult to achieve with classical computing. At present, quantum computing is still in the development stage, and there are many technical routes, including ion traps, nuclear magnetic resonance, photonic quantum systems, semiconductor quantum dots, superconducting quantum systems, and topological quantum computing systems. Among them, the topological quantum computing system is a highly anticipated technical solution. In order to realize topological quantum bits, a promising method is to prepare Josephson multi-junctions on the topological insulator Bi2Se3, and adjust the superconducting phase to a specific range to cause a topological phase transition, thereby realizing the operation and reading of topological quantum computing.

[0003] In topological quantum computing based on Josephson junctions, the manipulation of quantum bits heavily relies on the regulation of the phase difference in the junction region. The most common method of regulation is to change the superconducting phase by current excitation and external magnetic flux, thereby causing a change in the phase difference in the junction region. However, for the Josephson N-junction (N≥3) formed by multiple superconductors, due to the limitation of the single value of the superconducting phase, only the phase difference of N-1 junction regions can be adjusted, while the last junction region cannot be regulated autonomously. If the anomalous Josephson effect is used, an equivalent phase difference will be generated without being affected by the phase of the superconductor itself. Therefore, it is particularly important to provide a method for controlling the phase difference of the Josephson N-junction (N≥3) formed by multiple superconductors. Summary of the invention

[0004] Therefore, the purpose of the present invention is to overcome the defects in the prior art and provide a device based on the anomalous Josephson effect, its preparation and phase control method. The anomalous Josephson effect is used to control the phase difference of the junction area, thereby enriching the means of controlling the phase difference of the junction area, and at the same time, all phase differences of the Josephson multi-junction can be fully controlled, which is helpful for the future control and reading of topological quantum bits.

[0005] Before describing the present invention, the terms used in this article are defined as follows:

[0006] The term "CVD" means: Chemical Vapor Deposition.

[0007] The term "PMMA" means: polymethyl methacrylate.

[0008] The term "MIBK" means: methyl isobutyl ketone.

[0009] The term "MIBK:IPA=1:3" means a mixture of methyl isobutyl ketone and isopropyl alcohol in a volume ratio of 1:3.

[0010] The term "induced superconducting state" means that at low temperatures, when ordinary semiconductor materials are in contact with superconductors, the Cooper pairs in the superconductor will diffuse into the semiconductor, giving the semiconductor a certain degree of superconducting properties, thereby reducing resistance.

[0011] The term "Andreev bound state" refers to the stationary state mode formed by electrons or holes in the junction region inside a Josephson junction.

[0012] The term "Zeeman energy" refers to the energy gained by electrons in a magnetic field.

[0013] To achieve the above object, the first aspect of the present invention provides a device based on the anomalous Josephson effect, wherein the device based on the anomalous Josephson effect comprises, from bottom to top, a substrate, a nanosheet, a Josephson N-junction layer (N is an integer ≥ 3), a first metal film, an insulating layer, a detection electrode layer, and a second metal film;

[0014] Preferably, the substrate is a substrate with a marker array prepared in advance; and / or

[0015] Preferably, the device based on the anomalous Josephson effect is a Josephson triple junction device or a Josephson quadruple junction device, and most preferably a Josephson triple junction device.

[0016] According to the device based on the anomalous Josephson effect of the first aspect of the present invention, the substrate is a silicon substrate or an aluminum oxide substrate, and most preferably a silicon substrate;

[0017] The nanosheets are Bi2Se3 nanosheets or Bi2Te3 nanosheets, and most preferably Bi2Se3 nanosheets;

[0018] The thickness of the nanosheet is 20 to 50 nm, preferably 20 to 40 nm, and most preferably 30 nm;

[0019] The length of the nanosheet is 5 to 20 μm, preferably 5 to 15 μm, and most preferably 10 μm;

[0020] The thickness of the first metal film is 50-100 nm, preferably 60-90 nm, more preferably 70-90 nm, and most preferably 80 nm;

[0021] The thickness of the second metal film is 100-200 nm, preferably 120-180 nm, more preferably 140-170 nm, and most preferably 160 nm;

[0022] The Josephson N-junction device has a T-shaped or Y-shaped shape, and is most preferably a T-shaped shape;

[0023] The material of the insulating layer is overexposed PMMA glue or aluminum oxide, and the most preferred material is overexposed PMMA glue;

[0024] The metal of the first metal film is selected from one or more of the following: lead, aluminum, niobium, preferably lead, aluminum, most preferably lead; and / or

[0025] The metal of the second metal film is gold or palladium, and most preferably gold.

[0026] The second aspect of the present invention provides a method for preparing the device based on the anomalous Josephson effect according to the first aspect, the method comprising the following steps:

[0027] (1) growing nanosheets and transferring the grown nanosheets to a substrate;

[0028] (2) Positioning and photographing the nanosheet prepared in step (1), and drawing a circuit diagram of the Josephson N junction, the insulating layer, and the detection electrode based on the optical photograph taken;

[0029] (3) spin coating electron beam photoresist, baking, exposing and developing the Josephson N junction layer;

[0030] (4) Plating a metal film and removing the adhesive to obtain the device based on the anomalous Josephson effect.

[0031] According to the method of the second aspect of the present invention, in the step (1), the method for growing nanosheets is chemical vapor deposition (CVD).

[0032] According to the method of the second aspect of the present invention, in said step (3):

[0033] The electron beam photoresist is PMMA;

[0034] The glue coating machine is a desktop glue spreading machine;

[0035] The gluing time is 40 to 80 seconds, preferably 50 to 70 seconds, and most preferably 60 seconds;

[0036] The rotation speed of the glue coating is 2000-6000rpm, preferably 3000-5000rpm, and most preferably 4000rpm;

[0037] The baking time is 40 to 80 seconds, preferably 50 to 70 seconds, and most preferably 60 seconds;

[0038] The baking temperature is 100-150°C, preferably 110-140°C, and most preferably 120°C;

[0039] The exposure method is selected from one or more of the following: electron beam exposure, ultraviolet exposure, laser direct writing, preferably electron beam exposure or ultraviolet exposure, most preferably electron beam exposure;

[0040] The exposure dose of the exposure is 50 to 200 μA / cm 2 , preferably 50 to 150 μA / cm 2 , most preferably 100 μA / cm 2 ; and / or

[0041] The developer is MIBK, and most preferably MIBK with a ratio of MIBK:IPA=1:3.

[0042] According to the method of the second aspect of the present invention, the step (4) further comprises the following steps: plating a first layer of metal film, and then soaking, ultrasonicating and cleaning after degumming.

[0043] According to the method of the second aspect of the present invention, the step (4) further comprises the following steps:

[0044] (a) repeating step (3) to spin-coat an electron beam photoresist, bake, expose and develop the insulating layer;

[0045] (b) repeating step (3) to spin-coat the electron beam photoresist, bake, expose and develop the detection electrode layer;

[0046] (c) plating a second metal film, removing the glue, soaking, ultrasonicating and cleaning;

[0047] Preferably, the detection electrode is in contact with the center point of the Josephson N-junction region;

[0048] Preferably, the surface exposure dose of the insulating layer is 3000-5000 μA / cm 2 , preferably 3500~4500μA / cm 2 , the most preferred value is 4000μA / cm 2 ; and / or

[0049] Preferably, the surface exposure dose of the detection electrode layer is 50-200 μA / cm 2 , preferably 50 to 150 μA / cm 2 , most preferably 100 μA / cm 2 .

[0050] A third aspect of the present invention provides a phase control method, the phase control method comprising: using the device based on the anomalous Josephson effect according to claim 1 or 2 or the device based on the anomalous Josephson effect prepared according to any one of claims 3 to 7 to control the phase difference of superconductivity;

[0051] Preferably, the phase control includes the following steps: placing the prepared device based on the anomalous Josephson effect into a dilution refrigerator, applying an in-plane magnetic field after cooling to generate an anomalous Josephson effect, using a detection electrode to measure the change in contact resistance with the center point, and detecting the change in phase parameters based on the change in contact resistance.

[0052] According to the phase control method of the third aspect of the present invention, wherein:

[0053] The in-plane magnetic field is an in-plane magnetic field parallel to the junction region; and / or

[0054] The temperature of the cooling is 1 to 20 mK, more preferably 5 to 15 mK, and most preferably 10 mK.

[0055] According to the phase control method of the third aspect of the present invention, the phase control method further comprises: defining junction region 1, junction region 2 and junction region 3 clockwise, and when the Z-axis magnetic field Bz and the Y-axis magnetic field By are applied simultaneously,

[0056]

[0057]

[0058] φ3=-4πB z S / φ0 Formula (3);

[0059] Among them, φ1, φ2, and φ3 are the phase differences of the three clockwise junction regions; is the equivalent phase of the magnetic field By generated in the junction region 1 and the junction region 2; S is the loop area of ​​the Josephson junction; φ0 is a quantum magnetic flux; the junction region of the Josephson triple junction is induced into a superconducting state under the action of the superconducting electrode;

[0060] Preferably, when When the energy gap of the junction region of the Josephson triple junction is closed, the induced superconducting state enters the normal state, so that the contact resistance between the detection electrode and the detection electrode becomes larger.

[0061] According to a specific implementation case of the present invention, taking the Josephson triple junction as an example, the steps of preparing the Josephson triple junction device, preparing the detection electrode and phase control are as follows:

[0062] 1. Preparation of Josephson triple junction:

[0063] (1) Bi2Se3 nanosheets grown by chemical vapor deposition (CVD) are transferred to a silicon substrate on which a pre-prepared label array is present.

[0064] (2) Find the nanosheet with a thickness of about 30 nm and a size of more than 10 μm under an optical microscope, locate it, and take a photo; draw the circuit diagram of the "T"-shaped Josephson triple junction, insulating layer, and detection electrode based on the optical photo.

[0065] (3) Use a desktop coater to spin-coat electron beam photoresist and bake it on a hot plate. Use electron beam lithography to expose the Josephson triple junction layer and develop it.

[0066] (4) Place the device in a coating machine and coat it with two layers of titanium and aluminum. Finally, place the device in acetone to remove the glue and obtain a Josephson triple junction device.

[0067] 2. Preparation of detection electrodes:

[0068] (1) Use a desktop coater to spin-coat electron beam photoresist and bake it on a hot plate. Then use electron beam lithography to expose the insulating layer with a large dose (40 times the normal dose) to carbonize the photoresist in the exposed area.

[0069] (2) After washing away the remaining photoresist with acetone, an insulating layer can be obtained, so that the detection electrode prepared subsequently can only contact the center point of the junction area.

[0070] (3) Spin-coating electron beam photoresist, baking, and electron beam exposure to form a layer of detection electrode.

[0071] (4) After development, the electrode is placed in a coating machine and coated with two layers of titanium and gold. The electrode is then placed in acetone to remove the glue and obtain a detection electrode.

[0072] 3. Phase control:

[0073] (1) Place the device in a dilution refrigerator and, after cooling to the lowest temperature, use a detection electrode to measure the contact resistance with the center point.

[0074] (2) An in-plane magnetic field is applied parallel to the junction region, and the change in the phase parameter is detected based on the change in contact resistance.

[0075] According to another specific implementation case of the present invention, Figure 3 The figure is a schematic diagram showing the anomalous Josephson effect in a Josephson triple junction device. Figure 2 (b) shows a schematic diagram of the Josephson triple junction. The three junction regions are defined clockwise as junction region 1, junction region 2, and junction region 3. The phase differences of the junction regions are φ1, φ2, and φ3. When the in-plane magnetic fields Bz and By are applied simultaneously,

[0076]

[0077]

[0078] φ3=-4πB z S / φ0 Formula (3);

[0079] in, is the equivalent phase of the magnetic field By in the junction region 1 and the junction region 2; S is the loop area of ​​the Josephson junction; the junction region of the Josephson triple junction is induced into a superconducting state under the action of the superconducting electrode;

[0080] when When , the energy gap of the junction region of the Josephson triple junction is closed, and the induced superconducting state is converted into a normal state, so the contact resistance between the detection electrode and the detection electrode becomes larger. Figure 2 (b) is a theoretical schematic diagram of contact resistance, where dots represent low resistance and blanks represent high resistance. Figure 3 (a) is the SEM color-corrected image of the actual device. Figure 3 (b) is the actual measured contact resistance data graph with the Z-axis magnetic field Bz and the Y-axis magnetic field By. The range of the equivalent phase generated by the Y-axis magnetic field By is as follows: Figure 2 (b) As shown in the box.

[0081] According to another specific implementation case of the present invention, Figure 4 This is a schematic diagram of demonstrating the anomalous Josephson effect in another Josephson triple junction device. The three junction regions are defined clockwise as junction region 1, junction region 2, and junction region 3, and the phase differences of the junction regions are φ1, φ2, and φ3. When the in-plane magnetic fields Bz and By are applied simultaneously,

[0082]

[0083]

[0084] φ3=-4πB z S / φ0 Formula (3);

[0085] in, is the equivalent phase of the magnetic field By generated in junction region 1 and junction region 2; S is the loop area of ​​the Josephson junction.

[0086] when When the energy gap of the junction region of the Josephson triple junction is closed, the induced superconducting state is transformed into a normal state, so the contact resistance between the detection electrode and the detection electrode becomes larger. Figure 4 (a) is the SEM color-corrected image of the actual device. Figure 4 (b) is the actual measured data of the contact resistance changing with the magnetic field Bz and By.

[0087] The device based on the anomalous Josephson effect of the present invention may have but is not limited to the following beneficial effects:

[0088] The device based on the anomalous Josephson effect of the present invention utilizes the anomalous Josephson effect to regulate the phase difference of the junction region, thereby enriching the means of regulating the phase difference of the junction region, and can also completely control all phase differences of the Josephson multi-junction, which is helpful for the future manipulation and reading of topological quantum bits. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] The embodiments of the present invention are described in detail below with reference to the accompanying drawings, wherein:

[0090] Figure 1 The schematic diagram of the principle of the anomalous Josephson effect is shown. For the Josephson junction, electrons and holes will form an Andreev bound state. When the phases of the superconductors on both sides are When , there is a supercurrent in the junction region, and the supercurrent size is When a magnetic field By is applied along the y-axis, the electrons will generate additional momentum under the action of Zeeman energy, so that when the electrons move from one side of the junction to the other side, there will be an additional phase difference. So the final total superflow is

[0091] Figure 2 The schematic diagram of the Josephson triple junction based on the anomalous Josephson effect in Example 1 and the theoretical schematic diagram during measurement are shown. Figure 2 (a) is a schematic diagram of a Josephson triple junction device. The superconducting lead electrode forms a Josephson triple junction on the topological insulator. The three junction regions are defined clockwise as junction region 1, junction region 2, and junction region 3, and the phase differences of the junction regions are φ1, φ2, and φ3. Under the action of the insulating layer, the detection electrode only contacts the topological insulator in the junction region, and the direction of the magnetic field is shown by the arrow in the figure. Figure 2 (b) is a theoretical schematic diagram of the measurement. When the topological insulator is induced into a superconducting state by the superconducting electrode, the contact resistance between the detection electrode and the topological insulator is small. If the magnetic flux is adjusted so that

[0092] The energy gap of the topological insulator will close, changing from the induced superconducting state to the normal state, making the contact resistance between the detection electrode larger. The blank part in the figure represents that the junction region is in the normal state, that is, the high resistance state; the dotted part represents that the junction region enters the induced superconducting state, that is, the low resistance state. Figure 2 The horizontal axis of (b) is the equivalent phase, that is, The ordinate is the phase of the magnetic field generated by the Z axis, i.e. 2nB z S / φ0, as As the Z-axis magnetic field Bz increases, the high resistance state gradually splits and then merges again, and the process is repeated. Figure 2 (b) Only when the anomalous Josephson effect and the vertical magnetic field work together, can the two-dimensional graph shown in the figure be measured by formulas (1) to (3). Limited by the size of the Y-axis magnetic field By applied in the example, the box is the range that the anomalous phase can reach in the example.

[0093] Figure 3 The schematic diagram of the embodiment 1 demonstrating the anomalous Josephson effect in the Josephson triple junction device is shown. Figure 3 (a) is the SEM color-corrected image of the actual device. Figure 3 (b) is the actual measured contact resistance data graph with magnetic field Bz and By. Gray is low resistance state, white is high resistance state. As By increases, the high resistance state gradually splits into two branches and then merges together. The range of the equivalent phase generated by the magnetic field By is as follows: Figure 2 (b) As shown in the box.

[0094] Figure 4 FIG. 1 is a schematic diagram showing a demonstration of the anomalous Josephson effect in another Josephson triple junction device according to Embodiment 1. Figure 4 (a) is the SEM color-corrected image of the actual device. Figure 4 (b) is the actual measured contact resistance data graph with magnetic field Bz and By. Gray represents low resistance state and white represents high resistance state. As By increases, the high resistance state gradually splits into two branches and then merges together. Figure 2 Theoretical illustration in (b) Figure 1 To. DETAILED DESCRIPTION

[0095] The present invention is further described below by means of specific examples. However, it should be understood that these examples are only used for more detailed and specific description and should not be understood as limiting the present invention in any form.

[0096] This section generally describes the materials and test methods used in the experiments of the present invention. Although many materials and operating methods used to achieve the purpose of the present invention are well known in the art, the present invention is still described as detailed as possible. It is clear to those skilled in the art that in the context, if not specifically stated, the materials and operating methods used in the present invention are well known in the art.

[0097] The reagents and instruments used in the following examples are as follows:

[0098] Reagents:

[0099] PMMA 950A4 glue, MIBK (1:3), purchased from MicroChem;

[0100] Acetone, methanol, and isopropanol were purchased from Sinopharm Chemical Reagent Co., Ltd.

[0101] instrument:

[0102] Desktop glue spreader, purchased from Xinyouyan Electronic Technology (China) Co., Ltd., model MODEL KW-4A;

[0103] Magnetic stirrer, purchased from Shanghai Silu Instrument Co., Ltd., model B15-1;

[0104] Electron beam exposure system, purchased from Raith, model Raith150;

[0105] Wire bonder, purchased from West Bond, model 7476D;

[0106] Dilution refrigerator, purchased from Oxford, model TL400;

[0107] The lock-in amplifier was purchased from Japan NF Company, model LI5650.

[0108] Example 1

[0109] This embodiment is used to illustrate the method for preparing a device based on the anomalous Josephson effect of the present invention.

[0110] Taking the Josephson triple junction as an example, the preparation method includes the following steps:

[0111] (1) Sample transfer: Bi2Se3 nanosheets grown by chemical vapor deposition (CVD) are transferred to a silicon substrate with a pre-prepared label array on it.

[0112] (2) Glue coating: Use MicroChem PMMA 950A4 glue and spread the glue evenly on the silicon wafer using a desktop glue spreader at a speed of 4000 rpm for 1 minute. Then bake on a hot plate at a temperature of 120°C for 1 minute.

[0113] (3) Exposure: Electron beam exposure was performed on the Josephson triple junction layer on a Raith 150 system with the following parameters: aperture 30 μm, voltage 10 KV, surface exposure dose 100 μA / cm 2 After exposure, develop with MIBK (1:3) for one minute.

[0114] (4) Coating: Use an electron beam coating machine to coat titanium (Ti) 5nm and aluminum (Al) 80nm in sequence. Then remove the glue by soaking in acetone for half an hour, and then use ultrasound for 30s to remove the residual glue. Finally, clean the sample with isopropanol.

[0115] (5) Overexposure: Repeat step (2) to coat the photoresist, and then expose the insulating layer on the Raith150 system to carbonize the photoresist in the exposed area. The parameters are aperture 30μm, voltage 10KV, and surface exposure dose 4000μA / cm 2 After the exposure is completed, the photoresist is washed off by soaking in acetone for half an hour, and finally cleaned with isopropyl alcohol so that the detection electrode prepared later can only contact the center point of the junction area.

[0116] (6) Gluing and exposure: Repeat step (2) again, and then expose the detection electrode layer on the Raith150 system, with the parameters of aperture 30 μm, voltage 10 KV, and surface exposure dose 100 μA / cm 2 After exposure, develop with MIBK (1:3) for one minute.

[0117] (7) Coating: Use an electron beam coating machine to coat titanium (Ti) 5nm and gold (Au) 160nm in sequence. Then remove the glue, soak in acetone for half an hour, and then use ultrasound for 30 seconds to remove the residual glue. Finally, clean it with isopropyl alcohol to obtain a device based on the anomalous Josephson effect.

[0118] Example 2

[0119] This embodiment is used to illustrate the phase control of the device based on the anomalous Josephson effect prepared in Example 1.

[0120] (1) Packaging: Use WestBond bonding machine to connect to the measurement sample holder and place in the dilution refrigerator.

[0121] (2) Low-temperature measurement: Use a dilution refrigerator to cool the sample to 10 mK, apply an in-plane magnetic field parallel to the junction region, generate an anomalous Josephson effect and change the phase parameter, use a detection electrode to measure the change in contact resistance with the center point, and detect the change in phase parameter based on the change in contact resistance.

[0122] Example 3

[0123] This embodiment is used to illustrate the anomalous Josephson effect in the anomalous Josephson effect-based device prepared in Embodiment 1.

[0124] The specific measurement steps are as follows:

[0125] (1) Wiring: Select the device to be measured and determine the corresponding wiring port of the sample on the dilution refrigerator according to the packaging diagram. Use the four-terminal method to measure the resistance and use a coaxial line to connect the current input terminal of the device to the output terminal of the phase-locked amplifier. The current output terminal of the device is grounded and the two voltage measurement terminals are connected to the voltage input terminal of the phase-locked amplifier.

[0126] (2) Set up the lock-in amplifier: Set the lock-in amplifier to the voltage measurement AB mode and set the frequency of the output AC voltage to 13.7 Hz to prevent coupling of AC noise.

[0127] (3) Measure resistance: Adjust the output voltage amplitude of the phase-locked amplifier to 1mV, and connect an external 1M resistor to make the input current of the device input terminal 1nA. At this time, the voltage measurement terminal of the phase-locked amplifier can measure the voltage drop across the device, and divide it by the 1nA input current to get the resistance value.

[0128] (4) Data collection: Connect the phase-locked amplifier to the computer via the SR232 interface to collect data from the phase-locked amplifier.

[0129] (5) Applying magnetic field: Apply a perpendicular magnetic field Bz and an in-plane magnetic field By simultaneously, and observe the data as it changes with the magnetic field.

[0130] Figure 2 The schematic diagram and the measured theoretical diagram of the Josephson triple junction device are shown in Figure 2. Figure 2 (a) is a schematic diagram of a Josephson triple junction. The superconducting lead electrode forms a Josephson triple junction on the topological insulator. The three junction regions are defined clockwise as junction region 1, junction region 2, and junction region 3. The phase differences of the junction regions are φ1, φ2, and φ3. When the Z-axis magnetic field Bz and the Y-axis magnetic field By are applied simultaneously,

[0131]

[0132]

[0133] φ3=-4πB z S / φ0 Formula (3);

[0134] in, is the equivalent phase of the magnetic field By generated in junction region 1 and junction region 2, S is the loop area of ​​the Josephson junction, and φ0 is a quantum magnetic flux;

[0135] when When the energy gap of the junction region of the Josephson triple junction is closed, the induced superconducting state is transformed into a normal state, so that the contact resistance between the detection electrode and the detection electrode becomes larger.

[0136] Figure 2(b) is a theoretical schematic diagram of the center point contact resistance. When the topological insulator is induced into a superconducting state by the superconducting electrode, the contact resistance between the detection electrode and the center point topological insulator is small. If the magnetic flux is adjusted so that The energy gap of the triple junction region will be closed, that is, the energy gap of the topological insulator will be closed, and the induced superconducting state will change to the normal state, making the contact resistance between the detection electrode larger. The blank part in the figure represents that the junction region is in the normal state, that is, the high resistance state; the dotted part represents that the center point of the junction region enters the induced superconducting state, that is, the low resistance state. Figure 2 The horizontal axis of (b) is the equivalent phase The vertical axis is the phase 2nB generated by the Z-axis magnetic field z S / φ0, as As the high resistance state gradually splits, then merges again, and repeats this process. Under normal circumstances, applying a perpendicular magnetic field Bz alone cannot traverse the entire Figure 2 (b) Only when the anomalous Josephson effect and the perpendicular magnetic field act together,

[0137]

[0138]

[0139] φ3=-4πB z S / φ0 Formula (3);

[0140] Only then can the two-dimensional graph shown in the figure be measured. Limited by the size of the parallel magnetic field By applied in the example, the box is the range that the abnormal phase can reach in the example.

[0141] Figure 3 This is a schematic diagram showing the anomalous Josephson effect in a Josephson triple junction device. Figure 3 (a) is the SEM color-corrected image of the actual device. Figure 3 (b) is the actual measured contact resistance with magnetic field Bz and By. It can be clearly seen that the high resistance state splits into two branches and finally merges, which is consistent with the theoretical schematic. Figure 2 (b) is consistent, where the equivalent phase range produced by the magnetic field By is as follows Figure 2 (b) As shown in the box.

[0142] Example 4

[0143] This embodiment is used to illustrate the anomalous Josephson effect in another anomalous Josephson effect-based device prepared in Embodiment 1.

[0144] The specific measurement steps are as follows:

[0145] (1) Wiring: Select the device to be measured and determine the corresponding wiring port of the sample on the dilution refrigerator according to the packaging diagram. Use the four-terminal method to measure the resistance and use a coaxial line to connect the current input terminal of the device to the output terminal of the phase-locked amplifier. The current output terminal of the device is grounded and the two voltage measurement terminals are connected to the voltage input terminal of the phase-locked amplifier.

[0146] (2) Set up the lock-in amplifier: Set the lock-in amplifier to the voltage measurement AB mode and set the frequency of the output AC voltage to 13.7 Hz to prevent coupling of AC noise.

[0147] (3) Measure resistance: Adjust the output voltage amplitude of the phase-locked amplifier to 1mV, and connect an external 1M resistor to make the input current of the device input terminal 1nA. At this time, the voltage measurement terminal of the phase-locked amplifier can measure the voltage drop across the device, and divide it by the 1nA input current to get the resistance value.

[0148] (4) Data collection: Connect the phase-locked amplifier to the computer via the SR232 interface to collect data from the phase-locked amplifier.

[0149] (5) Applying magnetic field: Apply a perpendicular magnetic field Bz and an in-plane magnetic field By simultaneously, and observe the data as it changes with the magnetic field.

[0150] Figure 4 Schematic diagram for demonstrating the anomalous Josephson effect in a Josephson triple junction device.

[0151] Figure 4 (a) is the SEM color-corrected image of the actual device. Figure 4 (b) is the actual measured contact resistance data plotted against magnetic field Bz and By. It can also be clearly seen that the high resistance state splits into two branches and finally merges, which is consistent with the theoretical schematic. Figure 2 (b) are consistent.

[0152] Although the present invention has been described to a certain extent, it is obvious that appropriate changes in various conditions can be made without departing from the spirit and scope of the present invention. It is understood that the present invention is not limited to the embodiments described, but belongs to the scope of the claims, which includes equivalent replacements of each factor described.

Claims

1. A device based on the anomalous Josephson effect, characterized in that: The device based on the anomalous Josephson effect includes, from bottom to top, a substrate, a nanosheet, a Josephson N-junction layer, a first metal film, an insulating layer, a detection electrode layer, and a second metal film, wherein: N is an integer ≥ 3; and, The device is prepared by a method comprising the following steps: (1) growing nanosheets and transferring the grown nanosheets to a substrate; (2) Positioning and photographing the nanosheet prepared in step (1), and drawing a circuit diagram of the Josephson N junction, the insulating layer, and the detection electrode based on the optical photograph taken; (3) spin coating electron beam photoresist, baking, exposing and developing the Josephson N junction layer; (4) Plating a metal film and removing the adhesive to obtain the device based on the anomalous Josephson effect.

2. The device based on the anomalous Josephson effect according to claim 1, characterized in that: The substrate is a substrate with a label array prepared in advance; and / or The device based on the anomalous Josephson effect is a Josephson triple junction device and a Josephson quadruple junction device.

3. The device based on the anomalous Josephson effect according to claim 2, characterized in that: The device based on the anomalous Josephson effect is a Josephson triple junction device.

4. The device based on the anomalous Josephson effect according to any one of claims 1 to 3, characterized in that: The substrate is a silicon substrate or an aluminum oxide substrate; The nanosheets are Bi2Se3 nanosheets or Bi2Te3 nanosheets; The thickness of the nanosheet is 20 to 50 nm; The length of the nanosheet is 5 to 20 μm; The thickness of the first metal film is 50-100 nm; The thickness of the second metal film is 100-200 nm; The Josephson N-junction device has a "T" or "Y" shape; The material of the insulating layer is overexposed PMMA glue or aluminum oxide; The metal of the first metal film is selected from one or more of the following: lead, aluminum, niobium; and / or The metal of the second metal film is gold or palladium.

5. The device based on the anomalous Josephson effect according to claim 4, characterized in that: The substrate is a silicon substrate; The nanosheet is a Bi2Se3 nanosheet; The thickness of the nanosheet is 20 to 40 nm; The length of the nanosheet is 5 to 15 μm; The thickness of the first metal film is 60 to 90 nm; The thickness of the second metal film is 120-180 nm; The Josephson N-junction device has a "T" shape; The material of the insulating layer is overexposed PMMA glue; The metal of the first metal film is lead or aluminum; and / or The metal of the second metal film is gold.

6. The device based on the anomalous Josephson effect according to claim 5, characterized in that: The thickness of the nanosheet is 30 nm; The length of the nanosheet is 10 μm; The thickness of the first metal film is 70 to 90 nm; The thickness of the second metal film is 140-170 nm; and / or The metal of the first metal film is lead.

7. The device based on the anomalous Josephson effect according to claim 6, characterized in that: The thickness of the first metal film is 80 nm; and / or The thickness of the second metal film is 160 nm.

8. A method for preparing a device based on the anomalous Josephson effect according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: (1) growing nanosheets and transferring the grown nanosheets to a substrate; (2) Positioning and photographing the nanosheet prepared in step (1), and drawing a circuit diagram of the Josephson N junction, the insulating layer, and the detection electrode based on the optical photograph taken; (3) spin coating electron beam photoresist, baking, exposing and developing the Josephson N junction layer; (4) Plating a metal film and removing the adhesive to obtain the device based on the anomalous Josephson effect.

9. The method according to claim 8, characterized in that In the step (1): the method for growing nanosheets is chemical vapor deposition.

10. The method according to claim 8, characterized in that In the step (3): The electron beam photoresist is PMMA; The glue coating machine is a table-top glue spreader; The gluing time is 40 to 80 seconds; The speed of gluing is 2000~6000rpm; The baking time is 40 to 80 seconds; The baking temperature is 100-150°C; The exposure method is selected from one or more of the following: electron beam exposure, ultraviolet exposure, laser direct writing; The exposure dose of the exposure is 50 to 200 μA / cm 2 ; and / or The developer was MIBK.

11. The method according to claim 10, characterized in that In the step (3): The gluing time is 50 to 70 seconds; The rotation speed of the glue coating is 3000-5000rpm; The baking time is 50 to 70 seconds; The baking temperature is 110-140°C; The exposure method is electron beam exposure or ultraviolet exposure; The exposure dose of the exposure is 50-150 μA / cm 2 ; and / or The developer is MIBK with a ratio of MIBK:IPA=1:

3.

12. The method according to claim 11, characterized in that In the step (3): The gluing time is 60s; The speed of the glue coating is 4000 rpm; The baking time is 60s; The baking temperature is 120°C; The exposure method is electron beam exposure; and / or The exposure dose of the exposure is 100 μA / cm 2 .

13. The method according to claim 8, characterized in that The step (4) also includes the following steps: plating a first layer of metal film, degumming, soaking, ultrasonication, and cleaning.

14. The method according to any one of claims 8 to 13, characterized in that The step (4) further includes the following steps: (a) repeating step (3) to spin-coat an electron beam photoresist, bake, expose and develop the insulating layer; (b) repeating step (3) to spin-coat the electron beam photoresist, bake, expose and develop the detection electrode layer; (c) Plating a second metal film, removing the glue, soaking, ultrasonicating and cleaning.

15. The method according to claim 14, characterized in that: The detection electrode is in contact with the center point of the Josephson N-junction region; The surface exposure dose of the insulating layer is 3000-5000 μA / cm 2 ; and / or The surface exposure dose of the detection electrode layer is 50-200 μA / cm 2 .

16. The method according to claim 15, characterized in that: The surface exposure dose of the insulating layer is 3500-4500 μA / cm 2 ; and / or The surface exposure dose of the detection electrode layer is 50-150 μA / cm 2 .

17. The method according to claim 16, characterized in that: The surface exposure dose of the insulating layer is 4000 μA / cm 2 ; and / or The surface exposure dose of the detection electrode layer is 100 μA / cm 2 .

18. A phase control method, characterized in that: The phase control method comprises: using a device based on the anomalous Josephson effect according to any one of claims 1 to 7 or a device based on the anomalous Josephson effect prepared according to any one of claims 8 to 17 to control the phase difference of the superconductor, and the phase control comprises the following steps: placing the prepared device based on the anomalous Josephson effect into a dilution refrigerator, applying an in-plane magnetic field after cooling to generate an anomalous Josephson effect, using a detection electrode to measure the change in contact resistance with the center point, and detecting the change in phase parameters according to the change in contact resistance.

19. The phase control method according to claim 18, characterized in that: The phase control includes the following steps: placing the prepared device based on the anomalous Josephson effect into a dilution refrigerator, applying an in-plane magnetic field after cooling to generate an anomalous Josephson effect, using a detection electrode to measure the change in contact resistance with the center point, and detecting the change in phase parameters based on the change in contact resistance.

20. The phase control method according to claim 18 or 19, characterized in that: The in-plane magnetic field is an in-plane magnetic field parallel to the junction region; and / or The temperature of the cooling is 1-20 mK.

21. The phase control method according to claim 20, characterized in that: The temperature of the cooling is 5-15 mK.

22. The phase control method according to claim 21, characterized in that: The temperature of the cooling is 10 mK.

23. The phase control method according to claim 18, characterized in that: The phase control method further includes: defining junction region 1, junction region 2 and junction region 3 clockwise, and when a Z-axis magnetic field Bz and a Y-axis magnetic field By are applied simultaneously, φ3=-4πB z S / φ0 Formula (3); Among them, φ1, φ2, and φ3 are the phase differences of the three clockwise junction regions; is the equivalent phase of the magnetic field By generated in junction region 1 and junction region 2; S is the loop area of ​​the Josephson junction; φ0 is a quantum magnetic flux; the junction region of the Josephson triple junction is induced into a superconducting state under the action of the superconducting electrode.

24. The phase control method according to claim 23, characterized in that: when When the energy gap of the junction region of the Josephson triple junction is closed, the induced superconducting state is transformed into a normal state, so that the contact resistance between the detection electrode and the detection electrode becomes larger.

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