CN116015219A

CN116015219A - Josephson parametric amplifier

Info

Publication number: CN116015219A
Application number: CN202310079017.XA
Authority: CN
Inventors: 何楷泳; 戴根婷; 赵昌昊; 黄汝田; 余晴; 何永成; 耿霄; 吴歆宇; 杨亮亮; 程明俊; 陈国动; 刘建设; 陈炜
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2023-01-17
Filing date: 2023-01-17
Publication date: 2023-04-25

Abstract

The invention discloses a Josephson parametric amplifier, which only adopts two independent Josephson vibrators, so that the Josephson parametric amplifier is simple in structure, easy to prepare and low in process difficulty.

Description

Josephson parametric amplifier

Technical Field

The present application relates to the field of quantum computing, and in particular to a josephson parametric amplifier.

Background

In quantum circuits, low noise amplification of weak microwave signals is essential, while josephson parametric amplifiers (JPA, josephson Parametric Amplifier) are the most widely used devices.

In superconducting qubit test systems, signals need to be amplified by a multi-stage amplifier to be effectively measured by an instrument at the room temperature end. With the increasing number of qubits, the low temperature multistage amplification section in the test link needs to be integrated, otherwise it would pose a great challenge to the space and thermal load of the refrigerator. In the related art, the first stage amplifier adopts a reflective josephson parametric amplifier, and noise approaches to the standard quantum limit while providing proper gain and bandwidth, so that single-shot readout and feedback control of the quantum bit are possible. However, the reflective josephson parametric amplifier needs to be matched with a circulator in operation to separate the input signal from the amplified output signal, which will cause the following problems for the integration of the superconducting qubit sense amplifier link: because the circulator has a complex structure and needs multiple paths of control signals, the integration difficulty of the superconducting quantum bit read-out amplification link is increased; secondly, the overall bandwidth, dynamic range, noise and other performances of the superconducting quantum bit read-out amplification link are affected by the circulator; furthermore, direct inter-stage matching between multi-stage amplifiers is not possible, always requiring a circulator, which would be detrimental to improving the overall performance of the superconducting qubit sense amplifier link.

In summary, the reflective josephson parametric amplifier is not advantageous for integration of superconducting qubit sense amplifier links.

Disclosure of Invention

The Josephson parametric amplifier is simple in structure and beneficial to realizing integration of superconducting quantum bit readout amplification links.

The embodiment of the invention provides a Josephson parametric amplifier, which is provided with an input port and an output port, wherein a signal to be amplified enters the Josephson parametric amplifier from the input port, and the amplified signal is output from the output port; the josephson parametric amplifier comprises: one or more signal distribution and coupling structures, a first josephson oscillator, a second josephson oscillator, and one or more magnetic flux bias and pump input lines; wherein,

the signal distribution and coupling structure is respectively connected with the first Josephson oscillator, the second Josephson oscillator, the input port and the output port; the signal distribution and coupling structure is used for: performing phase shifting treatment on the signal to be amplified to obtain a first signal to be amplified and a second signal to be amplified, wherein the first signal to be amplified is transmitted to the first Josephson oscillator, and the second signal to be amplified is transmitted to the second Josephson oscillator; processing a first amplified signal from said first josephson oscillator and a second amplified signal from said second josephson oscillator to effect interference cancellation of said first amplified signal and said second amplified signal reflected back to said input port from said first josephson oscillator and said second josephson oscillator, said first amplified signal and said second amplified signal output to said output port after amplification of said first josephson oscillator and said second josephson oscillator being constructive;

The first Josephson vibrator and the second Josephson vibrator are respectively connected with the magnetic flux bias and the pumping input line in a mutual inductance way; the pumping signals on the magnetic flux bias and pumping input line are magnetic flux pumping signals, and the frequency of the pumping signals is in a microwave frequency band;

the first Josephson oscillator is used for carrying out mixing amplification on the first signal to be amplified and the microwave pumping signal to obtain the first amplified signal and transmitting the first amplified signal to the signal distribution and coupling structure;

and the second Josephson oscillator is used for carrying out frequency mixing amplification on the second signal to be amplified and the microwave pumping signal to obtain the second amplified signal and transmitting the second amplified signal to the signal distribution and coupling structure.

In an exemplary embodiment, the method further includes: more than two matching networks; the matching network is connected between the signal distribution and coupling structure and the first and second josephson oscillators for increasing the bandwidth of the josephson parametric amplifier.

In one illustrative example, the matching network is a distributed matching network, or a lumped matching network, or a hybrid of distributed and lumped matching networks;

When the matching network is a distributed matching network, the distributed matching network is formed by a microwave transmission line;

when the matching network is a lumped matching network, the lumped matching network is composed of on-chip or independent capacitance, inductance and resistance elements;

when the matching network is a distributed and lumped hybrid matching network, the distributed and lumped hybrid matching network is a combination of the distributed matching network and the lumped matching network.

In an illustrative example, when the matching network is a lumped matching network, the inductance in the lumped matching network is an equivalent inductance of a josephson junction or superconducting quantum interference SQUID.

In an illustrative example, the magnetic flux bias and pump input line includes one magnetic flux bias and pump input line, the first josephson vibrator and the second josephson vibrator being in mutual inductance connection with the same magnetic flux bias and pump input line;

alternatively, the magnetic flux bias and pump input line comprises two magnetic flux bias and pump input lines, and the first josephson vibrator and the second josephson vibrator are respectively connected with one independent magnetic flux bias and pump input line in a mutual inductance mode.

In an illustrative example, the magnetic flux bias and pump input lines include a dc bias signal for adjusting an operating point of the josephson oscillators of a mutual inductance connection and a microwave pump signal for implementing the mixing amplification;

the direct current bias signal and the microwave pumping signal are combined together through a biaser BiasTee element and then input into the magnetic flux bias and pumping input line.

In an exemplary embodiment, the phase shifting the signal to be amplified in the signal distribution and coupling structure to obtain a first signal to be amplified and a second signal to be amplified includes:

the power of the signal to be amplified is equally divided into two equal parts, 90-degree phase shifting is carried out on one of the equal parts, a first signal to be amplified and a second signal to be amplified are obtained, the second signal to be amplified is 90-degree more in phase shifting relative to the first signal to be amplified, the first signal to be amplified is output to the first Josephson oscillator, and the second signal to be amplified is output to the second Josephson oscillator.

In an illustrative example, the processing of the first amplified signal from the first josephson oscillator and the second amplified signal from the second josephson oscillator in the signal splitting and coupling structure includes:

Performing 90-degree phase shift on the second amplified signal reflected back to the input port by the second josephson oscillator, so that the second amplified signal is 180-degree more phase-shifted than the first amplified signal, and the phases of the first amplified signal and the second amplified signal reflected back to the input port are opposite to each other, and interference cancellation occurs; and carrying out 90-degree phase shift on the first amplified signal output to the output port by the first Josephson oscillator, so that the first amplified signal is 90-degree more phase-shifted than the second amplified signal, and the first amplified signal and the second amplified signal output to the output port have the same phase and generate interference constructive.

In one illustrative example, the signal distribution and coupling structure is one, and the magnetic flux bias and pump input line is one;

the first Josephson vibrator and the second Josephson vibrator are in a reflective working state;

the signal distribution and coupling structure is composed of an orthogonal hybrid network and comprises four ports, wherein a port 1 is the input port, a port 4 is the output port, a port 2 is connected with the first Josephson oscillator through the first matching network, and a port 3 is connected with the second Josephson oscillator through the second matching network; said first and second josephson oscillators are in mutual inductance connection with one of said flux bias and pump input lines;

The signal to be amplified enters the quadrature hybrid network through the port 1, the power of the signal to be amplified is equally divided into the first signal to be amplified and the second signal to be amplified, wherein the first signal to be amplified is transmitted to the port 2, the second signal to be amplified is transmitted to the port 3, and the second signal to be amplified transmitted to the port 3 is 90 DEG more phase-shifted than the first signal to be amplified transmitted to the port 2;

the first signal to be amplified enters the first Josephson oscillator through the first matching network to be amplified to obtain the first amplified signal, the first amplified signal is reflected back to the port 2, the second signal to be amplified enters the second Josephson oscillator through the second matching network to be amplified to obtain the second amplified signal, and the second amplified signal is reflected back to the port 3; the first amplified signal and the second amplified signal enter the quadrature hybrid network from port 2 and port 3 respectively and are transferred to the input port and the output port;

the second amplified signal reflected back to the port 3 is transmitted to the port 1 after 90-degree phase shifting, the first amplified signal reflected back to the port 2 is transmitted to the port 1 after 0-degree phase shifting, so that 180-degree phase difference exists between the first amplified signal and the second amplified signal reflected back to the port 1, and interference cancellation occurs; the first amplified signal reflected back to the port 2 is phase-shifted by 90 degrees and then transmitted to the port 4, the second amplified signal reflected back to the port 3 is phase-shifted by 0 degrees and then transmitted to the port 4, so that the first amplified signal and the second amplified signal transmitted to the port 4 have the same phase, and interference constructive occurs and then are output from the output port.

In one illustrative example, the signal distribution and coupling structure includes first and second magnetic flux bias and pump input lines for the first and second signal distribution and coupling structures, the magnetic flux bias and pump input lines; the matching network comprises a first matching network, a second matching network, a third matching network and a fourth matching network;

the first Josephson vibrator and the second Josephson vibrator are in a transmission type working state;

the first signal distribution and coupling structure is formed by a first orthogonal hybrid network and comprises four ports, wherein a port 11 is the input port, a port 12 is connected with the first Josephson oscillator through the first matching network, and a port 13 is connected with the second Josephson oscillator through the second matching network; port 14 connects to an impedance matching load; the second signal distribution and coupling structure is formed by a second orthogonal hybrid network and comprises four ports, wherein a port 23 is the output port, a port 22 is connected with an impedance matching load, a port 21 is connected with the first Josephson oscillator through the third matching network, and a port 24 is connected with the second Josephson oscillator through the fourth matching network; the first Josephson vibrator is in mutual inductance connection with the first magnetic flux bias and pump input line, and the second Josephson vibrator is in mutual inductance connection with the second magnetic flux bias and pump input line;

The signal to be amplified enters the first quadrature hybrid network through the port 11, the power of the signal to be amplified is divided into the first signal to be amplified, which is transmitted to the port 12, and the second signal to be amplified, which is transmitted to the port 13, and which is phase-shifted by 90 ° compared with the first signal to be amplified; the first signal to be amplified enters the first Josephson oscillator through the first matching network, and the second signal to be amplified enters the second Josephson oscillator through the second matching network; the first amplified signal amplified by the first josephson oscillator is reflected back to the port 12 and output to the port 21 via the third matching network; the second amplified signal amplified by the second josephson oscillator is reflected back to the port 13 and output to the port 24 via the fourth matching network;

the first amplified signal reflected back to the port 12 is transferred to the port 11 after being subjected to 0-degree phase shift, the second amplified signal reflected back to the port 13 is transferred to the port 11 after being subjected to 90-degree phase shift, so that a phase difference of 180 degrees exists between the first amplified signal and the second amplified signal reflected back to the port 11, and interference cancellation occurs; the first amplified signal reflected back to the port 12 is transmitted to the port 14 after 90 DEG phase shift, the second amplified signal reflected back to the port 13 is transmitted to the port 14 after 0 DEG phase shift, and the first amplified signal and the second amplified signal reflected back to the port 14 are consumed by the impedance matching load;

The first amplified signal transmitted to the port 21 is 90 ° phase-shifted and then transmitted to the port 23, the second amplified signal transmitted to the port 24 is 0 ° phase-shifted and then transmitted to the port 23, so that the first amplified signal and the second amplified signal transmitted to the port 23 have the same phase, and are output from the output port after interference and phase-shifting occur; the first amplified signal transmitted to the port 21 is phase-shifted by 0 ° and then transmitted to the port 22, and the second amplified signal transmitted to the port 24 is phase-shifted by 90 ° and then transmitted to the port 22, so that the first amplified signal and the second amplified signal transmitted to the port 22 have a phase difference of 180 ° and interference cancellation occurs.

The Josephson parametric amplifier is a transmission type magnetic flux pumping Josephson parametric amplifier based on a multipath signal interference principle, only two independent Josephson vibrators are adopted, the Josephson parametric amplifier is simple in structure and easy to prepare, the process difficulty is reduced, and compared with current pumping, an additional coupling structure and a filtering structure are not needed, the Josephson parametric amplifier is further ensured to be simple in structure, so that the Josephson parametric amplifier provided by the embodiment of the invention is beneficial to realizing integration of a superconducting quantum bit readout amplification link.

In one embodiment, when the josephson parametric amplifier provided by the embodiment of the application forms a multistage amplifier, the multistage amplifiers can be directly connected without a circulator, thereby being beneficial to realizing the integration of the superconducting quantum bit readout amplification link, avoiding extra inter-stage interference and improving the overall performance of the superconducting quantum bit readout amplification link.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

The accompanying drawings are included to provide a further understanding of the technical aspects of the present application, and are incorporated in and constitute a part of this specification, illustrate the technical aspects of the present application and together with the examples of the present application, and not constitute a limitation of the technical aspects of the present application.

Fig. 1 is a schematic diagram of the principle of josephson parametric amplifier composition in the embodiment of the present application;

fig. 2 is a schematic diagram of the composition structure of a first embodiment of the josephson parametric amplifier in the embodiment of the present application;

Fig. 3 is a schematic diagram of the composition of a second embodiment of the josephson parametric amplifier in the embodiment of the present application.

Detailed Description

For the purposes of making the objects, technical solutions and advantages of the present application more apparent, embodiments of the present application will be described in detail hereinafter with reference to the accompanying drawings. It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be arbitrarily combined with each other.

In order to facilitate an understanding of the present application, a more complete description of the present application will now be provided with reference to the relevant figures. Examples of the present application are given in the accompanying drawings. This application may, however, be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

It is to be understood that the terms "first," "second," and the like, as used herein, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, the meaning of "plurality" is at least two, such as two, three, etc., unless explicitly defined otherwise.

It is to be understood that in the following embodiments, "connected" is understood to mean "electrically connected", "communicatively connected", etc., if the connected circuits, modules, units, etc., have electrical or data transfer between them.

As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," and/or the like, specify the presence of stated features, integers, steps, operations, elements, components, or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof. Also, the term "and/or" as used in this specification includes any and all combinations of the associated listed items.

Fig. 1 is a schematic diagram of the composition principle of a josephson parametric amplifier in the embodiment of the present application, where the josephson parametric amplifier is a dual-port amplifier, and the josephson parametric amplifier is provided with an input port and an output port, a signal to be amplified enters the josephson parametric amplifier from the input port of the josephson parametric amplifier, and a signal amplified by the josephson parametric amplifier is output from the output port of the josephson parametric amplifier. As shown in fig. 1, the josephson parametric amplifier comprises at least: one or more signal distribution and coupling structures 101, a first josephson oscillator 1021, a second josephson oscillator 1022, and one or more magnetic flux bias and pump input lines 103; wherein,

The signal distribution and coupling structure 101 is respectively connected with the first josephson vibrator 1021, the second josephson vibrator 1022, the input port of the josephson parametric amplifier and the output port of the josephson parametric amplifier, and is used for performing phase shift processing on a signal to be amplified to obtain a first signal to be amplified and a second signal to be amplified, wherein the first signal to be amplified is transmitted to the first josephson vibrator 1021, and the second signal to be amplified is transmitted to the second josephson vibrator 1022; processing the first amplified signal from the first josephson vibrator 1021 and the second amplified signal from the second josephson vibrator 1022 to achieve interference cancellation of the first amplified signal and the second amplified signal reflected back to the input port from the first josephson vibrator 1021 and the second josephson vibrator 1022, and interference cancellation of the first amplified signal and the second amplified signal output to the output port after amplification of the first josephson vibrator 1021 and the second josephson vibrator 1022;

the first Josephson vibrator 1021 and the second Josephson vibrator 1022 are respectively connected with the magnetic flux bias and pumping input line 103 in a mutual inductance mode; the pumping signal on the flux bias and pump input line 103 is a flux pump, a microwave pumping signal at a frequency in the microwave band;

The first josephson oscillator 1021 is configured to mix and amplify a first signal to be amplified from the signal distribution and coupling structure 101 and a microwave pumping signal applied to the magnetic flux bias and pumping input line 103 to obtain a first amplified signal, and transmit the amplified first amplified signal to the signal distribution and coupling structure 101; the second josephson oscillator 1022 is configured to mix and amplify the second signal to be amplified from the signal distribution and coupling structure 101 and the microwave pumping signal applied to the magnetic flux bias and pumping input line 103 to obtain a second amplified signal, and transmit the amplified second amplified signal to the signal distribution and coupling structure 101.

The Josephson parametric amplifier is a transmission type magnetic flux pumping Josephson parametric amplifier based on a multipath signal interference principle, only two independent Josephson vibrators are adopted, the Josephson parametric amplifier is simple in structure and easy to prepare, the process difficulty is reduced, and compared with current pumping, an additional coupling structure and a filtering structure are not needed, the Josephson parametric amplifier is further ensured to be simple in structure, so that the Josephson parametric amplifier provided by the embodiment of the invention is beneficial to realizing integration of a superconducting quantum bit readout amplification link. In one embodiment, when the josephson parametric amplifier provided by the embodiment of the application forms a multistage amplifier, the multistage amplifiers can be directly connected without a circulator, thereby being beneficial to realizing the integration of the superconducting quantum bit readout amplification link, avoiding extra inter-stage interference and improving the overall performance of the superconducting quantum bit readout amplification link.

In an illustrative example, the josephson parametric amplifier provided in the embodiments of the present application may further include: two or more matching networks 104 are connected between the signal distribution and coupling structure 101 and the first josephson oscillator 1021 and the second josephson oscillator 1022 for increasing the bandwidth of the josephson parametric amplifier. In one embodiment, the matching network 104 may be comprised of a simple 50 ohm transmission line. In one embodiment, signal distribution and coupling structure 101 may be combined with matching network 104 to achieve both signal interference and impedance matching to achieve broadband amplification.

In one embodiment, as shown in fig. 1, the matching network 104 comprises a first matching network 1041, a second matching network 1042, the first matching network 1041 being connected between the signal distribution and coupling structure 101 and the first josephson oscillator 1021, the second matching network 1042 being connected between the signal distribution and coupling structure 101 and the second josephson oscillator 1022.

In an illustrative example, the first matching network 1041 may be constituted by a simple 50 ohm transmission line for connecting the first josephson oscillator 1021 with the signal distribution and coupling structure 101. The second matching network 1042 may be constituted by a simple 50 ohm transmission line for connecting the second josephson oscillator 1022 with the signal distribution and coupling structure 101.

In an illustrative example, the first matching network 1041 or the second matching network 1042 may be composed of a Klopfenstein (Klopfenstein) transmission line or a two-segment distributed resonant cavity. Thus, based on the Josephson parametric coupling network synthesis technology, higher-order broadband amplification can be realized.

In one illustrative example, the matching network 104 may be a distributed matching network, or a lumped matching network, or a hybrid of distributed and lumped matching networks. In one embodiment, the distributed matching network may be comprised of microwave transmission lines. In one embodiment, the lumped matching network may be comprised of capacitive, inductive, resistive elements on-chip or independent. In one embodiment, the distributed and lumped hybrid matching networks may be a combination of distributed and lumped matching networks. In one embodiment, the inductance in the lumped matching network may be an equivalent inductance of a josephson junction or SQUID.

In an illustrative example, the first josephson vibrator 1021 comprises a superconducting quantum interference device (SQUID) and a capacitor in parallel, and the second josephson vibrator 1022 comprises a SQUID and a capacitor in parallel. The first josephson oscillator 1021 and the second josephson oscillator 1022 may be identical. In one embodiment, the capacitance in parallel with the SQUID may be a parallel plate capacitance, an interdigital capacitance, or the like. In one embodiment, the SQUID may include one or more SQUIDs connected in series to achieve different bandwidths and dynamic ranges depending on the number of SQUIDs connected in series.

In an illustrative example, the first josephson vibrator 1021/second josephson vibrator 1022 includes both reflective and transmissive modes of operation.

In an illustrative example, the magnetic flux bias and pumping input line 103 may comprise one magnetic flux bias and pumping input line, i.e. the first josephson vibrator 1021 and the second josephson vibrator 1022 are mutually connected to the same magnetic flux bias and pumping input line. In this embodiment, the first josephson vibrator 1021 and the second josephson vibrator 1022 share the same magnetic flux bias and pump input line, further saving chip area and magnetic flux bias and pump ports.

In an illustrative example, the magnetic flux bias and pump input line 103 may comprise two magnetic flux bias and pump input lines, namely a first josephson vibrator 1021 and a second josephson vibrator 1022, each connected in mutual inductance with a separate magnetic flux bias and pump input line.

In an embodiment, the magnetic flux bias and pump input line 103 comprises a dc bias signal for adjusting the operating point of the josephson oscillator which is in mutual inductance connection with the magnetic flux bias and pump input line 103, and a microwave pump signal for achieving the mixing amplification. In the present embodiment, the pumping signal on the flux bias and pump input line 103 is a flux pump, a signal with a frequency in the microwave band, referred to herein as a microwave pumping signal. In practical applications, one end of the magnetic flux bias and pump input line 103 is connected to a microwave source to input a microwave signal, so that a current in a microwave frequency band appears on the magnetic flux bias and pump input line 103, and a magnetic flux in the microwave frequency band is induced.

In one embodiment, the DC bias signal and the microwave pump signal may be combined via a bias (BiasTee) element to input the magnetic flux bias and pump input line 103. Biasetee may consist of ultra-wideband, near-ideal, high frequency inductors and capacitors without resonance points. The direct current signal is used for adjusting the SQUID critical current and the corresponding equivalent inductance so as to realize the tuning of the operating points of Josephson vibrators (such as a first Josephson vibrator 1021 and/or a second Josephson vibrator 1022) which are connected with the magnetic flux bias and the pumping input line in a mutual inductance way; the microwave pumping signal is used for mixing with the input signals to be amplified (such as a first signal to be amplified and a second signal to be amplified) through the SQUID, and transmitting energy into the input signals to be amplified so as to realize the amplifying effect on the signals to be amplified.

In the embodiment of the application, on one hand, the microwave pumping signal is provided with an independent port and does not share one port with the input signal to be amplified, so that an additional coupler is not required to be used for coupling the signal to be amplified and the microwave pumping signal when the microwave pumping signal is applied, and the design simplification of the Josephson parametric amplifier is facilitated; on the other hand, since the microwave pump signal operates in the three-wave mixing state, the microwave pump signal has a frequency ω _p Equal to the frequency omega of the signal to be amplified _s With pump frequency omega generated during mixing _i The sum, i.e. omega _p ＝ω _s +ω _i ≈2ω _s Frequency ω of microwave pump signal _p Away from the frequency omega of the signal to be amplified _s Therefore, an additional filtering structure is not needed to filter the microwave pumping signals, the influence of the microwave pumping signals on the signals to be amplified is avoided, and the design simplification of the Josephson parametric amplifier is facilitated; on the other hand, because the pumping mode is magnetic flux pumping, when the Josephson parametric amplifier provided by the embodiment of the application forms a multistage amplifier, microwave pumping signals can not bring interstage influence among the Josephson parametric amplifiers at all stages, thereby being beneficial to simplifying the design of the Josephson parametric amplifier and improving the performance of the Josephson parametric amplifier.

In an exemplary embodiment, the phase shifting processing is performed on the signal to be amplified in the signal distributing and coupling structure 101 to obtain a first signal to be amplified and a second signal to be amplified, which includes:

the power of the signal to be amplified is equally divided into two equal parts, 90 DEG phase shift is carried out on one of the equal parts, so that a first signal to be amplified and a second signal to be amplified are obtained, the second signal to be amplified is 90 DEG phase shift relative to the first signal to be amplified, the first signal to be amplified is output to the first Josephson vibrator 1021, and the second signal to be amplified is output to the second Josephson vibrator 1022.

In an illustrative example, the processing of the first amplified signal from the first josephson vibrator 1021 and the second amplified signal from the second josephson vibrator 1022 in the signal distribution and coupling structure 101 comprises:

the second amplified signal reflected back to the input port of the josephson parametric amplifier by the second josephson oscillator 1022 is 90 ° phase shifted, so that the second amplified signal is 180 ° phase shifted relative to the first amplified signal, that is, the first amplified signal reflected back by the first josephson oscillator 1021 and the second josephson oscillator 1022 are opposite in phase to the second amplified signal, and interference cancellation occurs between the two amplified signals; the first amplified signal output from the first josephson oscillator 102 to the output port of the josephson parametric amplifier is 90 ° phase shifted such that the first amplified signal is 90 ° phase shifted with respect to the second amplified signal, i.e. the first amplified signal output from the first josephson oscillator 1021 and the second josephson oscillator 1022 are identical in phase to the second amplified signal output from the output port, and interference is constructive. In this way, the amplified signal appears only at the output port of the josephson parametric amplifier and the signal reflected back to the input port of the josephson parametric amplifier is suppressed.

In an illustrative example, the signal distribution and coupling structure 101 may be composed of distributed elements, or composed of lumped elements, or a mixture of both distributed elements and lumped elements to achieve a narrowband or wideband structure.

According to the transmission type magnetic flux pumping Josephson parametric amplifier based on the multipath signal interference principle, transmission type amplification is achieved, meanwhile, low reflection signals are kept, and extra interference to a measured quantum bit system is avoided. The Josephson parametric amplifier provided by the embodiment of the application only adopts two independent Josephson vibrators, so that the amplifier is simple in structure and easy to prepare, and the process difficulty is reduced. Compared with current pumping, the Josephson parametric amplifier provided by the embodiment of the application does not need an additional coupling structure and a filtering structure, so that the circuit complexity is reduced, and additional inter-stage interference is not brought when the Josephson parametric amplifier provided by the embodiment of the application forms a multistage amplifier. The transmission type magnetic flux pumping Josephson parametric amplifier provided by the embodiment of the application can be directly connected with the multistage amplifiers without a circulator, is favorable for integrating an amplifying link, can directly perform interstage matching, and is favorable for improving the overall performance of the amplifying link.

In one embodiment, the first josephson vibrator 1021 and the second josephson vibrator 1022 are reflective operating states, as shown in fig. 2, and the josephson parametric amplifier comprises at least: a signal distribution and coupling structure 101, a first josephson oscillator 1021, a second josephson oscillator 1022, a first matching network 1041, a second matching network 1042 and a flux bias and pumping input line 103.

In the first embodiment shown in fig. 2, the signal distribution and coupling structure 101 is formed by an orthogonal hybrid network 101 and includes four ports, wherein port 1 (shown as numeral (1) in fig. 2) is an input port of the josephson parametric amplifier, port 4 (shown as numeral (4) in fig. 2) is connected to an output port of the josephson parametric amplifier, port 2 (shown as numeral (2) in fig. 2) is connected to a first josephson oscillator 1021 via a first matching network 1041, and port 3 (shown as numeral (3) in fig. 2) is connected to a second josephson oscillator 1022 via a second matching network 1042; the first josephson vibrator 1021 and the second josephson vibrator 1022 share one magnetic flux bias and pump input line 103, i.e. the first josephson vibrator 1021 and the second josephson vibrator 1022 are respectively connected with the same magnetic flux bias and pump input line 103 in a mutual inductance manner. In this embodiment, the first josephson vibrator 1021 comprises a SQUID1 (abbreviated as SQ1 in the drawing) and a capacitor Cp1 connected in parallel, wherein SQUID1 is composed of two josephson junctions connected in parallel, and the second josephson vibrator 1022 comprises a SQUID2 (abbreviated as SQ2 in the drawing) and a capacitor Cp2 connected in parallel, wherein SQUID2 is composed of two josephson junctions connected in parallel.

As shown in fig. 2, the first end of the first matching network 1041 is configured to receive a first signal to be amplified from the port 2 of the quadrature hybrid network 101, and output a first amplified signal amplified from the first josephson oscillator 1021 to the port 2 of the quadrature hybrid network 101; a second terminal of the first matching network 1041 is connected to a first terminal of the capacitor Cp1 and a first terminal of the SQUID 1; the first end of the magnetic flux bias and pump input line 103 is used for receiving a direct current bias signal and a microwave pump signal, and the second end of the capacitor Cp1, the second end of the SQUID1 and the second end of the magnetic flux bias and pump input line 103 are grounded; wherein SQUID1 is in mutual inductance connection with flux bias and pump input line 103. A first signal to be amplified is input from a first end of the first matching network 1041, passes through the first matching network 1041, and enters the capacitors Cp1 and SQUID1. A dc bias signal is input into the flux bias and pump input line 103 from a first end of the flux bias and pump input line 103, wherein the dc bias signal is used to bias SQUID1, adjust the equivalent inductance of SQUID1, cause the josephson parametric amplifier to operate at the microwave frequency that needs to be amplified, and the microwave pump signal is used to power SQUID1. The amplified first amplified signal is output to port 2 of the quadrature hybrid 101 via a first end of the first matching network 1041.

As shown in fig. 2, the first end of the second matching network 1042 is configured to receive the second signal to be amplified from the port 3 of the quadrature hybrid network 101, and output the second amplified signal amplified from the second josephson oscillator 1022 to the port 3 of the quadrature hybrid network 101; a second end of the second matching network 1042 is connected to the first end of the capacitor Cp2 and the first end of SQUID 2; the first end of the magnetic flux bias and pump input line 103 is used for receiving a direct current bias signal and a microwave pump signal, and the second end of the capacitor Cp2, the second end of the SQUID2 and the second end of the magnetic flux bias and pump input line 103 are grounded; wherein SQUID2 is in mutual inductance with the flux bias and pump input line 103. The second signal to be amplified is input from the first end of the second matching network 1042, and enters the capacitors Cp2 and SQUID2 through the second matching network 1042. A dc bias signal for biasing SQUID2, adjusting the equivalent inductance of SQUID2, causes the josephson parametric amplifier to operate at the microwave frequency to be amplified and a microwave pump signal for powering SQUID2 are input into the flux bias and pump input line 103 from a first end of the flux bias and pump input line 103. The amplified second amplified signal is output to port 3 of the quadrature hybrid 101 via the first end of the second matching network 1042.

In the first embodiment shown in fig. 2, the magnetic flux bias and pump input line 103 may also include two magnetic flux bias and pump input lines, one of which is separately connected to SQUID1 in a mutual inductance manner, and the other of which is separately connected to SQUID2 in a mutual inductance manner.

In the first embodiment shown in fig. 2, two reflective josephson oscillators (i.e. the first josephson oscillator 1021 and the second josephson oscillator 1022) and the flux-biasing and pumping input line 103 form two independent reflective josephson parametric amplifiers. SQUID1/SQUID2 is equivalent to a magnetic flux-regulated nonlinear inductor, and the capacitor Cp 1/capacitor Cp2 connected in parallel with the inductor constitutes a resonator for resonant frequency parametric modulation, and by changing the direct bias current flowing through the magnetic flux bias and pump input line 103, the bias magnetic flux passing through the SQUID1/SQUID2 loop changes, so that the resonant frequency of the first josephson vibrator 1021/second josephson vibrator 1022 also changes. The microwave pumping signal is added on the basis of the direct current bias current, so that the resonance frequency of the first josephson vibrator 1021/the second josephson vibrator 1022 oscillates at the frequency of the microwave pumping signal, and the josephson parametric amplifier is in an operating state. At this time, the first signal to be amplified/the second signal to be amplified input into the quadrature hybrid network 101 enters the first josephson vibrator 1021/the second josephson vibrator 1022 through the first matching network 1041/the second matching network 1042, and frequency mixing occurs between the first signal to be amplified and the second signal to be amplified with the microwave pump signal, and energy is transferred from the microwave pump signal to the first signal to be amplified/the second signal to be amplified; then, the first signal to be amplified/the second signal to be amplified is amplified, and the amplified first amplified signal/the amplified second signal is reflected back to the quadrature hybrid network 101 along the original path (i.e. the first josephson vibrator 1021/the second josephson vibrator 1022→the first matching network 1041/the second matching network 1042→the port 2 of the quadrature hybrid network 101/the port 3 of the quadrature hybrid network 101).

As shown in fig. 2, in the first embodiment, an input signal (i.e., a signal to be amplified) first enters a quadrature hybrid network 101 through a port 1, the power of the signal to be amplified entering the port 1 is equally divided into two parts, wherein one part is that a first signal to be amplified (0 ° phase shift) is transferred to a port 2 opposite to the port 1, the other part is that a second signal to be amplified (90 ° phase shift) is transferred to a port 3 opposite to the port 1, and the second signal to be amplified transferred to the port 3 is one 90 ° phase shift more than the first signal to be amplified transferred to the port 2, so as to achieve quadrature coupling of the signals. That is, in the first embodiment, after the input signal passes through the quadrature hybrid network 101, the input signal is equally divided into 2 parts and is transmitted to the port 2 and the port 3 of the quadrature hybrid network 101, and the two parts have a phase difference of 90 °; after that, the first signal to be amplified enters the first josephson vibrator 1021 through the first matching network 1041, the first amplified signal is reflected back to the port 2 of the quadrature hybrid network 101 along the original path (i.e. the first josephson vibrator 1021→the first matching network 1041→the quadrature hybrid network 101), the second signal to be amplified enters the second josephson vibrator 1022 through the second matching network 1042, and the second amplified signal is reflected back to the port 3 of the quadrature hybrid network 101 along the original path (i.e. the second josephson vibrator 1022→the second matching network 1042→the quadrature hybrid network 101). After the first and second amplified signals enter the quadrature hybrid network 101 from port 2 and port 3, respectively, the first and second amplified signals are both passed to the input port (i.e. port 1) and the output port (i.e. port 4) of the josephson parametric amplifier. The second amplified signal reflected back to the port 3 is phase-shifted by 90 degrees and then transmitted to the port 1, the first amplified signal reflected back to the port 2 is phase-shifted by 0 degrees and then transmitted to the port 1, so that the first amplified signal and the second amplified signal reflected back to the port 1 have a phase difference of 180 degrees, that is, the phases of the first amplified signal and the second amplified signal reflected back to the port 1 are opposite, and interference cancellation occurs; the first amplified signal reflected back to the port 2 is transmitted to the port 4 after 90 ° phase shift, the second amplified signal reflected back to the port 3 is transmitted to the port 4 after 0 ° phase shift, so that the phase between the first amplified signal transmitted to the port 4 and the second amplified signal is identical, interference phase correlation occurs and then the signals are output from the output port, that is, the amplified signals only appear at the output port (namely the port 4) of the josephson parametric amplifier, and the signals reflected back to the port 1 of the josephson parametric amplifier are suppressed. In the first embodiment, the josephson parametric amplifier realizes transmission amplification through mutual interference between two paths of signals.

In one embodiment, the first josephson vibrator 1021 and the second josephson vibrator 1022 are in transmission operation, and as shown in fig. 3, the josephson parametric amplifier comprises at least: two signal splitting and coupling structures 101 (first signal splitting and coupling structure 1011, second signal splitting and coupling structure 1012 shown in fig. 3), a first josephson vibrator 1021, a second josephson vibrator 1022, four matching networks 104 (first matching network 1041, second matching network 1042, third matching network 1043 and fourth matching network 1044 shown in fig. 3), and two flux bias and pump input lines 103 (first flux bias and pump input line 1031, second flux bias and pump input line 1032 shown in fig. 3).

In the second embodiment shown in fig. 3, the josephson parametric amplifier comprises four ports, but corresponds to a two-port amplifier, the port 11 of the first signal distribution and coupling structure 1011 is the input port of the josephson parametric amplifier (such as port 1 in fig. 3), the port 23 of the second signal distribution and coupling structure 1012 is the output port of the josephson parametric amplifier (such as port 3 in fig. 3), and the port 14 of the first signal distribution and coupling structure 1011 and the port 22 of the second signal distribution and coupling structure 1012 are respectively impedance matched with loads, and are respectively connected with resistances of a preset resistance value such as 50 ohms (Ω). The signal to be amplified is input from an input port (such as the port 11 of the first signal distributing and coupling structure 1011), amplified and transmitted to an output port (such as the port 23 of the second signal distributing and coupling structure 1012) for output, thereby realizing transmission type amplification.

In the second embodiment shown in fig. 3, the signal distribution and coupling structure 1011 is formed by an orthogonal hybrid network 1011 and comprises four ports, wherein port 11 is an input port of a josephson parametric amplifier, port 14 is connected to an impedance matching 50Ω load, port 12 is connected to a first josephson oscillator 1021 via a first matching network 1041, and port 13 is connected to a second josephson oscillator 1022 via a second matching network 1042; the second signal distribution and coupling structure 1012 is formed by an orthogonal hybrid network 1012 and comprises four ports, wherein a port 23 is an output port of the josephson parametric amplifier, a port 22 is connected with an impedance matching 50Ω load, a port 21 is connected with a first josephson oscillator 1021 through a third matching network 1043, and a port 24 is connected with a second josephson oscillator 1022 through a fourth matching network 1044; the first josephson vibrator 1021 is in mutual inductance connection with a first magnetic flux bias and pump input line 1031 and the second josephson vibrator 1022 is in mutual inductance connection with a second magnetic flux bias and pump input line 1032. In this embodiment, the first josephson vibrator 1021 comprises a SQUID1 (abbreviated as SQ1 in the drawing) and a capacitor Cp1 connected in parallel, wherein SQUID1 is composed of two josephson junctions connected in parallel, and the second josephson vibrator 1022 comprises a SQUID2 (abbreviated as SQ2 in the drawing) and a capacitor Cp2 connected in parallel, wherein SQUID2 is composed of two josephson junctions connected in parallel.

As shown in fig. 3, the first end of the first matching network 1041 is configured to receive a first signal to be amplified from the port 12 of the quadrature hybrid 1011 and reflect the first amplified signal from the first josephson oscillator 1021 back to the port 12 of the first quadrature hybrid 1011; a second terminal of the first matching network 1041 is connected to a first terminal of the capacitor Cp1 and a first terminal of the SQUID 1; the first end of the magnetic flux bias and pump input line 1031 is configured to receive a first dc bias signal and a first microwave pump signal, and the second end of the capacitor Cp1, the second end of the SQUID1, and the second end of the magnetic flux bias and pump input line 1031 are all grounded; wherein SQUID1 is in mutual inductance with flux bias and pump input line 1031. The first signal to be amplified is input from the first end of the first matching network 1041, enters the capacitor Cp1 and SQUID1 through the first matching network 1041, and the first amplified signal amplified by the first josephson oscillator 1021 is reflected back to the port 12 of the first quadrature hybrid 1011 through the first end of the first matching network 1041. A first dc bias signal for biasing SQUID1, adjusting the equivalent inductance of SQUID1, causes the first josephson oscillator 1021 to operate at the microwave frequency to be amplified, and a first microwave pump signal for powering SQUID1 is input into the flux bias and pump input line 1031 from a first end of the flux bias and pump input line 1031. A first end of the third matching network 1043 is connected to the first end of the capacitor Cp1 and the first end of the SQUID1, and a second end of the third matching network 1043 is configured to output the first amplified signal amplified by the first josephson oscillator 1021 to the port 21 of the quadrature hybrid 1012.

As shown in fig. 3, the first end of the second matching network 1042 is configured to receive the second signal to be amplified after the 90 ° phase shift from the port 13 of the first quadrature hybrid 1011 and reflect the second amplified signal amplified from the second josephson oscillator 1022 back to the port 13 of the first quadrature hybrid 1011; a second end of the second matching network 1042 is connected to the first end of the capacitor Cp2 and the first end of SQUID 2; the first end of the flux bias and pump input line 1032 is configured to receive the second dc bias signal and the second microwave pump signal, and the second end of the capacitor Cp2, the second end of the SQUID2, and the second end of the flux bias and pump input line 1032 are grounded; wherein SQUID2 is in mutual inductance with flux bias and pump input line 1032. The second signal to be amplified is input from the first end of the second matching network 1042, enters the capacitor Cp2 and SQUID2 through the second matching network 1042, and the second amplified signal amplified by the second josephson vibrator 1022 is reflected back to the port 13 of the first quadrature hybrid 1011 through the first end of the second matching network 1042. A second dc bias signal for biasing SQUID2, adjusting the equivalent inductance of SQUID2, operating the second josephson oscillator 1022 at the microwave frequency to be amplified, and a second microwave pump signal for powering SQUID2 are input into the flux bias and pump input line 1032 from a first end of the flux bias and pump input line 1032. A first end of the fourth matching network 1044 is connected to the first end of the capacitor Cp2 and the first end of the SQUID2, and a second end of the fourth matching network 1044 is configured to output the second amplified signal amplified by the second josephson oscillator 1022 to the port 24 of the quadrature hybrid 1012.

In the second embodiment shown in fig. 3, two transmitting josephson oscillators (i.e. the first josephson oscillator 1021 and the second josephson oscillator 1022) form two independent transmitting josephson parametric amplifiers with two magnetic flux bias and pump input lines (i.e. the first magnetic flux bias and pump input line 1031 and the second magnetic flux bias and pump input line 1032), respectively. The first josephson vibrator 1021/second josephson vibrator 1022 is the same as in the first embodiment, equivalent to a resonator with a resonance frequency parameter modulation, and amplification is achieved by mixing the microwave pump signal with the signal to be amplified of the input signal. The second embodiment is different from the first embodiment in that the first amplified signal/second amplified signal amplified by the first josephson vibrator 1021/second josephson vibrator 1022 is transmitted to the port 21 of the second quadrature hybrid network 1012 via the third matching network 1043/fourth matching network 1044 in addition to being reflected back to the first quadrature hybrid network 1011 along the input path (i.e. the first josephson vibrator 1021/second josephson vibrator 1022→the first matching network 1041/second matching network 1042→the port 12 of the first quadrature hybrid network 1011/port 13 of the first quadrature hybrid network 1011).

As shown in fig. 3, in the second embodiment, the input signal (i.e. the signal to be amplified) first enters the first quadrature hybrid network 1011 via the port 11 (i.e. the port 1 of the josephson parametric amplifier), the power of the signal to be amplified entering the port 11 will be divided equally into two parts, one part, i.e. the first signal to be amplified (0 ° phase shift), is transferred to the port 12 opposite to the port 11, the other part, i.e. the second signal to be amplified (90 ° phase shift), is transferred to the port 13 diagonally opposite to the port 11, and the second signal to be amplified transferred to the port 13 is phase shifted by one 90 ° compared to the first signal to be amplified transferred to the port 12, so as to achieve the quadrature coupling of the signals. That is, in the second embodiment, the input signal to be amplified passes through the first quadrature hybrid 1011 and is equally divided into 2 parts and transmitted to the

ports

12 and 13 of the first quadrature hybrid 1011, and the two parts have a phase difference of 90 °; after that, the first signal to be amplified enters the first josephson oscillator 1021 via the first matching network 1041, and the second signal to be amplified enters the second josephson oscillator 1022 via the second matching network 1042, wherein the second signal to be amplified reaching the second josephson oscillator 1022 is 90 ° out of phase with the first signal to be amplified reaching the first josephson oscillator 1021.

Then, the first amplified signal amplified by the first josephson oscillator 1021 is reflected back to the port 12 of the first quadrature hybrid network 1011 along the original path (i.e., the first josephson oscillator 1021→the first matching network 1041→the first quadrature hybrid network 1011), and is output to the port 21 of the second quadrature hybrid network 1012 through the third matching network 1043; the second amplified signal amplified by the second josephson oscillator 1022 is reflected back to the port 13 of the first quadrature hybrid network 1011 along the original path (i.e. the second josephson oscillator 1022→the second matching network 1042→the first quadrature hybrid network 1011), and is output to the port 24 of the second quadrature hybrid network 1012 via the fourth matching network 1044. The first amplified signal reflected back to the port 12 is transferred to the port 11 after being subjected to 0-degree phase shift, and the second amplified signal reflected back to the port 13 is transferred to the port 11 after being subjected to 90-degree phase shift, so that a phase difference of 180 degrees exists between the first amplified signal and the second amplified signal reflected back to the port 11; the first amplified signal reflected back to the port 12 is phase-shifted by 90 degrees and then transmitted to the port 14, the second amplified signal reflected back to the port 13 is phase-shifted by 0 degrees and then transmitted to the port 14, so that the phases of the first amplified signal and the second amplified signal reflected back to the port 14 are identical, that is, the phases of the first amplified signal and the second amplified signal reflected back to the port 11 are opposite, interference cancellation occurs, the phases of the first amplified signal and the second amplified signal reflected back to the port 14 are identical, interference constructive occurs, and the first amplified signal and the second amplified signal are consumed by a load. The first amplified signal transmitted to the port 21 is transmitted to the port 23 after 90 DEG phase shift, the second amplified signal transmitted to the port 24 is transmitted to the port 23 after 0 DEG phase shift, so that the phases of the first amplified signal transmitted to the port 23 and the second amplified signal are the same, and the first amplified signal and the second amplified signal are output from an output port (namely, the port 3 of the Josephson parametric amplifier) after interference phase correlation; the first amplified signal transmitted to the port 21 is phase-shifted by 0 ° and then transmitted to the port 22, and the second amplified signal transmitted to the port 24 is phase-shifted by 90 ° and then transmitted to the port 22, so that the first amplified signal and the second amplified signal transmitted to the port 22 have a phase difference of 180 ° and interference cancellation occurs. That is, the amplified signal appears only at port 3 of the josephson parametric amplifier and the signal reflected back to port 1 of the josephson parametric amplifier is suppressed. When the josephson parametric amplifier is in operation, the ports 2 and 4 of the josephson parametric amplifier are connected to a matching load of 50 ohms, and the signals transferred to the ports 2 and 4 are consumed on the load. Thus, in the second embodiment, the signal to be amplified is input from the input port (i.e. port 1) of the josephson parametric amplifier, and after being amplified by the two josephson oscillators, the signal to be amplified is output from the output port (i.e. port 3) of the josephson parametric amplifier, so that the transmission amplification from port 1 to port 3 is realized.

In the above embodiments, the signal distribution and coupling structure 101 is merely an example of a quadrature hybrid network, but the implementation form of the signal distribution and coupling structure 101 is not limited, and the protection scope of the present application is not limited.

Although the embodiments disclosed in the present application are described above, the embodiments are only used for facilitating understanding of the present application, and are not intended to limit the present application. Any person skilled in the art to which this application pertains will be able to make any modifications and variations in form and detail of implementation without departing from the spirit and scope of the disclosure, but the scope of the application is still subject to the scope of the claims appended hereto.

Claims

1. A josephson parametric amplifier, wherein the josephson parametric amplifier is provided with an input port from which a signal to be amplified enters the josephson parametric amplifier and an output port from which the amplified signal is output; the josephson parametric amplifier comprises: one or more signal distribution and coupling structures, a first josephson oscillator, a second josephson oscillator, and one or more magnetic flux bias and pump input lines; wherein,

2. The josephson parametric amplifier of claim 1, further comprising: more than two matching networks; the matching network is connected between the signal distribution and coupling structure and the first and second josephson oscillators for increasing the bandwidth of the josephson parametric amplifier.

3. The josephson parametric amplifier of claim 2, wherein the matching network is a distributed matching network, or a lumped matching network, or a hybrid of distributed and lumped matching networks;

4. The josephson parametric amplifier of claim 3, wherein when the matching network is a lumped matching network, the inductance in the lumped matching network is an equivalent inductance of a josephson junction or superconducting quantum interferometer SQUID.

5. The josephson parametric amplifier of claim 1, wherein the flux-biasing and pumping input line comprises one flux-biasing and pumping input line, the first josephson oscillator and the second josephson oscillator being in mutual inductance connection with the same flux-biasing and pumping input line;

6. The josephson parametric amplifier of claim 5, wherein the magnetic flux bias and pump input lines comprise a dc bias signal for adjusting an operating point of the mutual inductance connected josephson oscillator and a microwave pump signal for effecting the mixing amplification;

7. The josephson parametric amplifier of claim 1, wherein the phase shifting of the signal to be amplified in the signal splitting and coupling structure results in a first signal to be amplified and a second signal to be amplified, comprising:

8. The josephson parametric amplifier of claim 1, wherein the processing of the first amplified signal from the first josephson oscillator and the second amplified signal from the second josephson oscillator in the signal splitting and coupling structure comprises:

9. The josephson parametric amplifier of claim 2, wherein the signal splitting and coupling structure is one, the magnetic flux bias and pump input line is one;

10. The josephson parametric amplifier of claim 2, wherein the signal splitting and coupling structures comprise first and second magnetic flux biasing and pumping input lines for the first and second signal splitting and coupling structures; the matching network comprises a first matching network, a second matching network, a third matching network and a fourth matching network;