Josephson parametric amplifier, method for manufacturing a Josephson parametric amplifier, and method for driving a Josephson parametric amplifier

Abstract

In a Josephson parametric amplifier (JPA) equipped with a superconducting quantum interference device (SQUID), thermal noise caused by the magnetic flux supply source to the SQUID is suppressed. [Solution] The Josephson parametric amplifier includes a substrate, a superconducting quantum interference element having a Josephson junction provided on the substrate, a ring-shaped structure made of a superconductor provided to cover the superconducting quantum interference element, and a magnetic flux generating unit that generates a magnetic flux passing through the inside of the ring of the ring-shaped structure.

Description

Technical Field

[0001] The disclosed technology relates to a Josephson parametric amplifier, a method for manufacturing a Josephson parametric amplifier, and a method for driving a Josephson parametric amplifier.

Background Art

[0002] As technologies related to amplifiers using superconducting quantum interference devices (SQUIDs: Superconducting QUantum Interference Devices), the following technologies are known. Patent Document 1 describes a configuration in which a guard ring is provided around a SQUID in a material inspection apparatus having a detection circuit including a magnetic sensor using a SQUID and a signal processing circuit that processes a signal output from the detection circuit.

[0003] Patent Document 2 describes a traveling wave parametric amplifier including a coplanar waveguide having at least one Josephson junction element that interrupts a central trace of the coplanar waveguide, and at least one shunt capacitor coupled to the coplanar waveguide. The first plate of the capacitor is formed by the central trace of the coplanar waveguide, and the second plate of the capacitor is formed by a conductive trace forming an air bridge structure.

[0004] Patent Document 3 describes a parametric amplifier including an LC resonator including a dc-SQUID in which Josephson junctions are arranged in parallel as a component, and a direct current magnetic flux bias line, and flux-biasing the dc-SQUID using the direct current magnetic flux bias line.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] The integration of superconducting qubits is being actively pursued with the aim of realizing quantum computers. In the integration of superconducting qubits, one of the important research challenges is how to read out the qubits quickly and efficiently. A method called "dispersive readout" is used to read out superconducting qubits. In dispersed readout, the qubit is not read out directly, but rather read out through the response of a resonator coupled to the qubit. The resonant frequency of the resonator shifts (dispersive shift) according to the state of the qubit. The state of the qubit can be determined by observing the amount of shift in the resonant frequency after irradiating it with microwaves. Since the signal level used in dispersed readout is weak, it is necessary to amplify the signal with a low-noise amplifier. A superconducting amplifier called a Josephson Parametric Amplifier (JPA) is used for this purpose.

[0007] The superconducting quantum interference device (SQUID), the main component of a Josephson parametric amplifier (JPA), forms a superconducting closed loop. When a shielding current flows through this closed loop, the amount of magnetic flux trapped inside the loop is quantized. To drive a JPA, a continuous application of magnetic flux through the SQUID loop is required. In other words, during the operation of a quantum computer, a continuous power supply is needed to the inductor that provides the magnetic flux to the SQUID. Thermal noise generated by the power supply to the inductor can degrade the read-through fidelity of the qubits.

[0008] The disclosed technology aims to suppress thermal noise caused by the magnetic flux supply source to a superconducting quantum interference device (SQUID) in a Josephson parametric amplifier (JPA) having a SQUID. [Means for solving the problem]

[0009] The Josephson parametric amplifier relating to the disclosed technology includes a substrate, a superconducting quantum interference element having a Josephson junction provided on the substrate, a ring-shaped structure made of a superconductor provided so as to cover the superconducting quantum interference element, and a magnetic flux generating unit that generates a magnetic flux passing through the inside of the ring of the ring-shaped structure. [Effects of the Invention]

[0010] According to the disclosed technology, it is possible to suppress thermal noise caused by the source of magnetic flux supplied to a superconducting quantum interference device (SQUID) in a Josephson parametric amplifier (JPA). [Brief explanation of the drawing]

[0011] [Figure 1] This is an equivalent circuit diagram showing an example of the configuration of a Josephson parametric amplifier according to an embodiment of the disclosed technology. [Figure 2] This figure schematically shows how a magnetic flux is applied to a SQUID using a magnetic flux generation unit and a ring-shaped structure according to an embodiment of the disclosed technology. [Figure 3] This diagram schematically illustrates how magnetic flux is applied to a SQUID without using a ring-shaped structure. [Figure 4] This is a plan view showing an example of the configuration around a SQUID and a ring-shaped structure according to an embodiment of the disclosed technology. [Figure 5A] This is a cross-sectional view along the line 5A-5A in Figure 4. [Figure 5B] This is a cross-sectional view along the line 5B-5B in Figure 4. [Figure 5C] This is a cross-sectional view along the 5C-5C line in Figure 4. [Figure 6A] It is a cross-sectional view showing an example of a method for manufacturing a Josephson parametric amplifier according to an embodiment of the disclosed technology. [Figure 6B] It is a cross-sectional view showing an example of a method for manufacturing a Josephson parametric amplifier according to an embodiment of the disclosed technology. [Figure 6C] It is a cross-sectional view showing an example of a method for manufacturing a Josephson parametric amplifier according to an embodiment of the disclosed technology. [Figure 6D] It is a cross-sectional view showing an example of a method for manufacturing a Josephson parametric amplifier according to an embodiment of the disclosed technology. [Figure 6E] It is a cross-sectional view showing an example of a method for manufacturing a Josephson parametric amplifier according to an embodiment of the disclosed technology. [Figure 6F] It is a cross-sectional view showing an example of a method for manufacturing a Josephson parametric amplifier according to an embodiment of the disclosed technology. [Figure 7] It is a plan view showing an example of a method for manufacturing a Josephson parametric amplifier according to an embodiment of the disclosed technology. [Figure 8] It is a cross-sectional view showing an example of the configuration of a Josephson parametric amplifier according to another embodiment of the disclosed technology.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, an example of an embodiment of the disclosed technology will be described with reference to the drawings. In each drawing, the same or equivalent components and parts are given the same reference numerals, and duplicate descriptions are omitted.

[0013] FIG. 1 is an equivalent circuit diagram showing an example of the configuration of a Josephson parametric amplifier (hereinafter referred to as JPA) 10 according to an embodiment of the disclosed technology. The JPA 10 is used in an extremely low temperature environment (for example, about 10 mK) together with a superconducting qubit not shown.

[0014] The JPA10 includes a JPA resonator 20, a pump signal generation unit 30, a ring-shaped structure 40, a magnetic flux generation unit 50, an impedance matching circuit 60, a circulator 70, a HEMT (High Electron Mobility Transistor) 80, and a low-noise amplifier 90.

[0015] The impedance matching circuit 60 includes inductive and capacitive components and is placed in the signal path. The impedance matching circuit 60 suppresses signal reflection, making it possible to maximize the signal transmission efficiency between the qubit, which is the signal source, and the JPA resonator 20. It also makes it possible to optimize performance in a specific frequency band and extend the operating range of the JPA resonator 20.

[0016] The circulator 70 is used to ensure the unidirectionality of the signal. That is, the circulator 70 separates the signal read from the qubit from the signal amplified by the JPA resonator 20. This prevents interference between the input signal and the amplified signal. In Figure 1, the input and output paths of the signal are shown by dashed arrows.

[0017] The JPA resonator 20 includes a superconducting quantum interference element (hereinafter referred to as SQUID) 21 and a capacitor 27 connected in parallel to the SQUID 21. The SQUID 21 contains two Josephson junctions 22 within the circumference of a ring made of superconductor. When the magnetic flux passing through the ring changes, the tunnel current flowing through the Josephson junctions 22 changes in integer multiples of the magnetic flux quantum. Due to this property, the SQUID 21 functions as a highly sensitive magnetometer. The JPA resonator 20 amplifies the signal by a parametric amplification process by temporally modulating the equivalent inductance of the SQUID 21 with a pump signal supplied from the pump signal generation unit 30.

[0018] The pump signal generation unit 30 generates a pump signal for modulating the nonlinear inductance of the SQUID 21. The pump signal generation unit 30 has a signal source 31 and a waveguide 32 containing an inductor component. By modulating the nonlinear inductance, which is a circuit parameter of the SQUID 21, with a pump signal having a frequency twice the resonant frequency, parametric amplification is induced in the JPA resonator 20. Parametric amplification enables extremely high-sensitivity and low-noise signal amplification.

[0019] By adjusting the magnetic flux applied to SQUID21, the effective inductance of SQUID21 can be changed, thereby adjusting the resonant frequency of the JPA resonator 20. This allows for optimization of the operating point of the JPA resonator 20, improving performance in a specific frequency band. The magnetic flux is applied to SQUID21 by the magnetic flux generation unit 50 and the ring-shaped structure 40.

[0020] The ring-shaped structure 40 is a ring-shaped structure made of a superconductor that is provided to cover the SQUID 21. Due to the Meissner effect, magnetic flux cannot penetrate into the interior of the superconductor. However, magnetic flux can pass through the opening (hole) 41 on the inside of the ring-shaped structure 40 made of superconductor. The magnetic flux passing through the opening 41 of the ring-shaped structure 40 is an integer multiple of the magnetic flux quantum and is held inside the ring. The magnetic flux quantum held inside the ring behaves as a superconducting electromagnet.

[0021] The magnetic flux generating unit 50 generates a magnetic flux that passes through the opening 41 of the ring-shaped structure 40. The magnetic flux generating unit 50 has an inductor 52 and a current source 51. The inductor 52 is typically a DC coil. A current supplied from the current source 51 flows through the inductor 52, generating a magnetic flux, which then passes through the opening 41 of the ring-shaped structure 40. A voltage source can also be used instead of the current source 51.

[0022] Figure 2 schematically shows an embodiment in which magnetic flux is applied to SQUID 21 using the magnetic flux generation unit 50 and the ring-shaped structure 40. When the ring-shaped structure 40, which is made of a superconductor, is in a superconducting state, the magnetic flux Φ0 generated by the magnetic flux generation unit 50 passes through the opening 41 of the ring-shaped structure 40, causing an induced current I1 to flow through the ring-shaped structure 40. Since superconductors have zero electrical resistance, the induced current I1 becomes a persistent current, and the ring-shaped structure 40 continuously generates a DC magnetic flux Φ1. As a result, the ring-shaped structure 40 behaves as a static magnet and continuously and stably supplies magnetic flux Φ1 to SQUID 21.

[0023] As long as the superconducting state of the ring-shaped structure 40 does not collapse, the magnetic flux quanta inside the ring will not decay. In other words, the behavior of the ring-shaped structure 40 as a static magnet is permanent at extremely low temperatures. After the magnetic flux is retained inside the ring of the ring-shaped structure 40, the behavior of the ring-shaped structure 40 as a static magnet will continue even if the supply of magnetic flux φ0 from the magnetic flux generation unit 50 is stopped.

[0024] On the other hand, as shown in Figure 3, if the ring-shaped structure 40 is absent, the magnetic flux generation unit 50 needs to continuously supply magnetic flux φ0 to SQUID21 during qubit operation. In this case, power is continuously supplied to the inductor 52. Thermal noise generated by the power supply to the inductor reduces the readout fidelity of the qubit in JPA10. In addition, power consumption becomes enormous.

[0025] As shown in Figure 2, by supplying magnetic flux to the SQUID 21 via the ring-shaped structure 40, power supply to the inductor 52 becomes unnecessary after the magnetic flux is held inside the ring of the ring-shaped structure 40, thus eliminating the problems of thermal noise and power consumption.

[0026] The signal amplified by the JPA resonator 20 is amplified by the HEMT 80 and then amplified again by the low-noise amplifier 90, which is placed at room temperature. Because the HEMT 80 operates over a wide bandwidth, it can efficiently process the signal amplified by the JPA resonator 20 over a wide frequency range. The combination of the JPA resonator 20 and the HEMT 80 is highly effective in achieving both high-sensitivity amplification and low-noise characteristics. The output signal of the low-noise amplifier 90 is detected by a network analyzer (not shown).

[0027] Figure 4 is a plan view showing an example of the configuration around SQUID21 and the ring-shaped structure 40. Figures 5A, 5B, and 5C are cross-sectional views along lines 5A-5A, 5B-5B, and 5C-5C in Figure 4, respectively.

[0028] The SQUID 21 and the ring-shaped structure 40 are provided on a substrate 15. For example, a silicon substrate can be used as the substrate 15. The two Josephson junctions 22 constituting the SQUID 21 each have two superconducting layers 25 and an extremely thin insulating layer 26, about a few nanometers thick, sandwiched between the two superconducting layers 25. For example, aluminum (Al) can be used as the material for the superconducting layer 25, and for example, aluminum oxide (Al2O3) can be used as the material for the insulating layer 26. One of the superconducting layers 25 functions as a signal electrode 23, and the other of the superconducting layer 25 functions as a ground electrode 24. The SQUID 21 is formed by patterning the superconducting layer 25 into a ring shape that includes the two Josephson junctions 22 around its circumference.

[0029] A signal waveguide 11 and a ground plane 12 made of a superconductor are provided on the substrate 15. The signal electrode 23 of SQUID 21 is connected to the signal waveguide 11, and the ground electrode 24 of SQUID 21 is connected to the ground plane 12. Niobium (Nb), for example, can be used as the superconductor constituting the signal waveguide 11 and the ground plane 12. The ground plane 12 is provided on both the top and bottom (or left and right) sides of SQUID 21, sandwiching SQUID 21 in between.

[0030] The ring-shaped structure 40 is provided so as to cover the SQUID 21. As shown in Figure 4, the opening 41 of the ring-shaped structure 40 is positioned to overlap with the SQUID 21 in a plan view. The ring-shaped structure 40 has a bridge structure that straddles the SQUID 21. The ring-shaped structure 40 has two pier sections connected to the ground plane 12 via an insulating film 14 on both sides of the SQUID 21, and an arch section that passes over the SQUID 21 and connects the two pier sections. For example, aluminum (Al) can be used as the superconductor constituting the ring-shaped structure 40. The insulating film 14 is provided at the connection points with the ring-shaped structure 40 on the ground plane 12 on both sides of the SQUID 21. A silicon nitride film (Si3N4) can be used as the insulating film 14.

[0031] As shown in Figure 4, the waveguide 13 of the pump signal generated by the pump signal generation unit 30 is led to the vicinity of the SQUID 21 on the substrate 15, and its termination is connected to the ground plane 12.

[0032] The manufacturing method of JPA10 will be described below with reference to Figures 6A to 6F and Figure 7. First, a superconducting metal film constituting the signal waveguide 11 and ground plane 12 is formed on the surface of the substrate 15 using a film deposition method such as sputtering. For example, a silicon substrate can be used as the substrate 15, and niobium (Nb) can be used as the material for the superconducting metal film.

[0033] Next, an insulating film 14 is formed on the surface of the superconducting metal film using a film deposition method such as plasma CVD (Chemical Vapor Deposition). For example, silicon nitride (Si3N4) can be used as the material for the insulating film 14. Next, the insulating film 14 is patterned by photolithography and wet etching. The insulating film 14 is removed except for the connection part with the ring-shaped structure 40.

[0034] Next, the superconducting metal film is patterned by photolithography and dry etching. This forms signal waveguides 11, ground planes 12, pump signal waveguides 13, etc., on the substrate 15 (Figure 6A).

[0035] Next, a SQUID 21 is formed on the surface of the substrate 15. Specifically, a resist mask (not shown) for forming the pattern of the SQUID 21 by lift-off is formed on the surface of the substrate 15. Next, a superconductor layer 25 / insulator layer 26 / superconductor layer 25 is formed sequentially using a film deposition method such as electron beam evaporation. For example, aluminum (Al) can be used as the material for the superconductor layer 25, and for example, aluminum oxide (Al2O3) can be used as the material for the insulator layer 26. Next, the excess superconductor layer 25 is removed along with the resist mask. The SQUID 21 is formed by patterning the superconductor layer 25 into a ring shape that includes two Josephson junctions 22 around its circumference (Figure 6B). The signal electrode 23 and ground electrode 24 are formed by patterning the superconductor layer 25. Figure 7 is a plan view of the JPA 10 at this stage.

[0036] Next, a resist mask 110 is formed on the surface of the substrate 15 to form a bridge structure for the ring-shaped structure 40. The resist mask 110 has openings 111 that expose the surface of the insulating layer 26 (Figure 6C).

[0037] Next, a superconducting film 42 constituting the ring-shaped structure 40 is formed using a film deposition method such as electron beam evaporation, so as to cover the surface of the resist mask 110. The superconducting film 42 covers the entire surface of the resist mask 110 and is connected to the insulating film 14 exposed at the opening 111 of the resist mask 110 (Figure 6D).

[0038] Next, the superconducting film 42 is patterned by photolithography and etching. This forms a ring-shaped structure 40 having an opening 41 in the center (Figure 6E).

[0039] Next, the resist mask 110 is removed using an organic solvent. This forms the bridge structure of the ring-shaped structure 40 (Figure 6F). Next, the magnetic flux generating unit 50 is positioned to match the substrate 15. That is, the magnetic flux generating unit 50 and the substrate 15 are aligned so that the magnetic flux φ0 generated by the magnetic flux generating unit 50 passes through the inside of the ring of the ring-shaped structure 40.

[0040] As described above, the JPA10 according to the embodiment of the disclosed technology includes a substrate 15, a SQUID 21 having a Josephson junction provided on the substrate 15, a ring-shaped structure 40 made of a superconductor provided to cover the SQUID 21, and a magnetic flux generating unit 50 that generates a magnetic flux passing through the inside of the ring of the ring-shaped structure 40. The ring-shaped structure 40 has an opening 41 at a position that overlaps with the SQUID 21 in a plan view. The ring-shaped structure 40 has a bridge structure that straddles the SQUID 21.

[0041] The method for driving the JPA10 according to the disclosed technology includes providing a ring-shaped structure 40 made of a superconductor so as to cover a SQUID21 having a Josephson junction provided on a substrate 15, generating an induced current I1 flowing through the ring-shaped structure 40 by supplying a magnetic flux Φ0 passing inside the ring of the ring-shaped structure 40 from a magnetic flux generation unit 50 while the ring-shaped structure 40 is in a superconducting state, and stopping the supply of magnetic flux Φ0 from the magnetic flux generation unit 50 after generating the induced current I1 while the ring-shaped structure 40 is in a superconducting state.

[0042] According to the JPA10 according to the disclosed technology embodiment, the magnetic flux Φ0 generated by the magnetic flux generation unit 50 passes through the opening 41 of the ring-shaped structure 40 made of superconductor, causing a persistent current to circulate within the ring-shaped structure 40. As a result, the ring-shaped structure 40 behaves as a static magnet, continuously and stably supplying magnetic flux Φ1 to the SQUID 21. The behavior of the ring-shaped structure 40 as a static magnet is permanent as long as the superconducting state is maintained within the ring-shaped structure 40. That is, after the magnetic flux is held inside the ring of the ring-shaped structure 40, the behavior of the ring-shaped structure 40 as a static magnet continues even if the supply of magnetic flux Φ0 from the magnetic flux generation unit 50 is stopped. Therefore, according to the JPA10 according to this embodiment, it is possible to continue supplying magnetic flux to the SQUID 21 without consuming power. This makes it possible to suppress thermal noise caused by the magnetic flux supply source to the SQUID 21 and to reduce power consumption.

[0043] In the above explanation, a configuration in which the ring-shaped structure 40 is connected to the ground plane 12 via an insulating film 14 was illustrated. However, as shown in Figure 8, the ring-shaped structure 40 may be directly connected to the ground plane 12. If there is a potential difference between opposing ground planes 12 with the SQUID 21 in between, the characteristics of the JPA 10 may change. By directly connecting the ring-shaped structure 40 to the ground plane 12, the opposing ground planes 12 with the SQUID 21 in between are electrically connected via the ring-shaped structure 40. This makes it possible to reduce the potential difference between the ground planes 12, thereby suppressing changes in the characteristics of the JPA 10.

[0044] The following additional information is disclosed regarding the embodiments described above. (Note 1) circuit board and A superconducting quantum interference element having a Josephson junction provided on the substrate, A ring-shaped structure made of a superconductor is provided so as to cover the superconducting quantum interference element, A magnetic flux generating unit that generates a magnetic flux passing through the inside of the ring-shaped structure, A Josephson parametric amplifier, including a Josephson parametric amplifier.

[0045] (Note 2) The ring-shaped structure has an opening in a position that overlaps with the superconducting quantum interference element in a plan view. The Josephson parametric amplifier described in Appendix 1.

[0046] (Note 3) The ring-shaped structure has a bridge structure that spans the superconducting quantum interference element. A Josephson parametric amplifier as described in Appendix 1 or Appendix 2.

[0047] (Note 4) The substrate has a ground plane made of a superconductor, which is provided so as to sandwich the superconducting quantum interference element between them. The ring-shaped structure is connected to the ground plane. The Josephson parametric amplifier described in Appendix 3.

[0048] (Note 5) The substrate has a ground plane made of a superconductor, which is provided so as to sandwich the superconducting quantum interference element between them. The ring-shaped structure is connected to the ground plane via an insulating film. The Josephson parametric amplifier described in Appendix 3.

[0049] (Note 6) The superconducting quantum interference element has a pump signal generation unit that generates a pump signal for modulating the nonlinear inductance of the superconducting quantum interference element. A Josephson parametric amplifier as described in any one of the appendices 1 through 5.

[0050] (Note 7) A process for forming a superconducting quantum interference device having a Josephson junction on a substrate, A step of forming a ring-shaped structure made of a superconductor so as to cover the superconducting quantum interference element, A step of arranging a magnetic flux generating unit that generates a magnetic flux passing through the inside of the ring in the ring-shaped structure at a position that is aligned with the substrate, A method for manufacturing a Josephson parametric amplifier, including the following:

[0051] (Note 8) The ring-shaped structure has an opening in a position that overlaps with the superconducting quantum interference element in a plan view. The manufacturing method described in Appendix 7.

[0052] (Note 9) The ring-shaped structure has a bridge structure that spans the superconducting quantum interference element. The manufacturing method described in Appendix 7 or Appendix 8.

[0053] (Note 10) The process further includes the step of forming a ground plane made of a superconductor on the substrate such that the superconducting quantum interference element is sandwiched between them, The ring-shaped structure is connected to the ground plane. A manufacturing method described in any one of the appendices 7 to 9.

[0054] (Note 11) The process further includes the step of forming a ground plane made of a superconductor on the substrate such that the superconducting quantum interference element is sandwiched between them, The ring-shaped structure is connected to the ground plane via an insulating film. A manufacturing method described in any one of the appendices 7 to 9.

[0055] (Note 12) A ring-shaped structure made of a superconductor is provided to cover a superconducting quantum interference element having a Josephson junction, which is provided on a substrate. When the superconductor of the ring-shaped structure is exhibiting a superconducting state, an induced current is generated flowing through the ring-shaped structure by supplying a magnetic flux passing through the inside of the ring in the ring-shaped structure. When the superconductor of the ring-shaped structure is exhibiting a superconducting state, the supply of magnetic flux is stopped after the induced current is generated. A method for driving a Josephson parametric amplifier. [Explanation of Symbols]

[0056] 10 Josephson Parametric Amplifier 15 circuit boards 20 JPA resonator 22 Josephson junction 30 Pump signal generation unit 40 Ring-shaped structure 50 Magnetic flux generation section

Claims

1. circuit board and A superconducting quantum interference element having a Josephson junction provided on the substrate, A ring-shaped structure made of a superconductor is provided so as to cover the superconducting quantum interference element, A magnetic flux generating unit that generates a magnetic flux passing through the inside of the ring-shaped structure, A Josephson parametric amplifier, including a Josephson parametric amplifier.

2. The ring-shaped structure has an opening in a position that overlaps with the superconducting quantum interference element in a plan view. The Josephson parametric amplifier according to claim 1.

3. The ring-shaped structure has a bridge structure that spans the superconducting quantum interference element. The Josephson parametric amplifier according to claim 1.

4. The substrate has a ground plane made of a superconductor, which is provided so as to sandwich the superconducting quantum interference element between them. The ring-shaped structure is connected to the ground plane. The Josephson parametric amplifier according to claim 3.

5. The substrate has a ground plane made of a superconductor, which is provided so as to sandwich the superconducting quantum interference element between them. The ring-shaped structure is connected to the ground plane via an insulating film. The Josephson parametric amplifier according to claim 3.

6. The superconducting quantum interference element has a pump signal generation unit that generates a pump signal for modulating the nonlinear inductance of the superconducting quantum interference element. The Josephson parametric amplifier according to claim 1.

7. A process for forming a superconducting quantum interference device having a Josephson junction on a substrate, A step of forming a ring-shaped structure made of a superconductor so as to cover the superconducting quantum interference element, A step of arranging a magnetic flux generating unit that generates a magnetic flux passing through the inside of the ring in the ring-shaped structure at a position that is aligned with the substrate, A method for manufacturing a Josephson parametric amplifier, including the following:

8. A ring-shaped structure made of a superconductor is provided to cover a superconducting quantum interference element having a Josephson junction, which is provided on a substrate. When the superconductor of the ring-shaped structure is exhibiting a superconducting state, an induced current is generated flowing through the ring-shaped structure by supplying a magnetic flux passing through the inside of the ring in the ring-shaped structure. In the state in which the superconductor of the ring-shaped structure exhibits a superconducting state, the supply of magnetic flux is stopped after the induction current is generated. A method for driving a Josephson parametric amplifier.

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