阅读说明：本技术 使用具有非重叠带宽的级联多路干涉测量约瑟夫逊定向放大器选择性放大频率复用微波信号 (Selective amplification of frequency multiplexed microwave signals using cascaded multi-path interferometric josephson directional amplifiers with non-overlapping bandwidths ) 是由 B.阿卜杜 于 2018-01-05 设计创作，主要内容包括：一种级联选择性微波定向放大器(级联体),包括约瑟夫逊器件的集合,所述集合中的每个约瑟夫逊器件具有微波频率的对应操作带宽。不同的操作带宽具有不同的对应中心频率。串联耦合被形成在来自所述集合的第一约瑟夫逊器件与来自所述集合的第n约瑟夫逊器件之间。串联耦合使得第一约瑟夫逊器件在通过串联耦合的第一信号流方向上放大来自频率复用微波信号(复用信号)的第一频率的信号,并且使得第n约瑟夫逊器件在通过串联的第二信号流方向上放大第n频率的信号,其中第二信号流方向与第一信号流方向相反。(A cascaded selective microwave directional amplifier (cascade) comprising a set of josephson devices, each josephson device in the set having a corresponding operating bandwidth at a microwave frequency. Different operating bandwidths have different corresponding center frequencies. A series coupling is formed between a first josephson device from the set and an nth josephson device from the set. The series coupling causes the first josephson device to amplify a signal at a first frequency from the frequency multiplexed microwave signal (multiplexed signal) in a first signal flow direction through the series coupling, and causes the nth josephson device to amplify a signal at an nth frequency in a second signal flow direction through the series coupling, wherein the second signal flow direction is opposite to the first signal flow direction.)

1. A cascaded selective microwave directional amplifier (cascade), comprising:

a set of Josephson devices, each Josephson device in the set having a corresponding operating bandwidth at a microwave frequency, wherein different operating bandwidths have different corresponding center frequencies; and

a series coupling between a first Josephson device from the set and an nth Josephson device from the set, wherein the series coupling causes the first Josephson device to amplify signals from a first frequency of a frequency multiplexed microwave signal (multiplexed signal) in a first signal flow direction through the series coupling and causes the nth Josephson device to amplify signals at an nth frequency in a second signal flow direction through the series, wherein the second signal flow direction is opposite to the first signal flow direction.

2. The cascade of claim 1, further comprising:

(n-1) th Josephson device from the set in the series coupling, wherein n is greater than 1, wherein the (n-1) th Josephson device is included in the series coupling between the first Josephson device and the n-th Josephson device, and wherein the (n-1) th Josephson device amplifies a signal from an (n-1) th frequency of the multiplexed signal in the first signal flow direction.

3. The cascade of claim 1, further comprising:

(n-1) th Josephson device from the set in the series coupling, wherein n is greater than 1, wherein the (n-1) th Josephson device is included in the series coupling between the first Josephson device and the n-th Josephson device, and wherein the (n-1) th Josephson device amplifies a signal from an (n-1) th frequency of the multiplexed signal in the second signal flow direction.

4. The cascade body of claim 1,

wherein the series coupling causes the first Josephson device to propagate a signal at the nth frequency from the multiplexed signal without amplification in the first signal flow direction through the series coupling and causes the nth Josephson device to propagate a signal at the first frequency without amplification in the second signal flow direction through the series coupling.

5. The cascade body of claim 1,

wherein the series coupling causes the first Josephson device to propagate signals of all frequencies incoming to the first Josephson device from the multiplexed signal without amplification in the first signal flow direction through the series coupling except for signals of the first frequency and to selectively amplify signals of the first frequency, an

Wherein the series coupling causes the nth Josephson device to propagate signals of all frequencies incoming to the nth Josephson device from the multiplexed signal without amplification in the direction of the second signal flow through the series coupling except for the signal of the nth frequency and to selectively amplify the signal of the nth frequency.

6. The cascade body of claim 1,

wherein a first operating bandwidth corresponding to a microwave frequency of the first Josephson device is non-overlapping for at least some frequencies with an nth operating bandwidth corresponding to a microwave frequency of the nth Josephson device.

7. The cascade body of claim 6, wherein the first and second,

wherein a total amplification bandwidth of the cascaded volume comprises the first operational bandwidth and the Nth operational bandwidth.

8. The cascade of claim 1, wherein the first josephson device of the set of josephson devices is an MPIJDA comprising:

a first non-degenerate microwave parametric amplifier device (first parametric amplifier);

a second non-degenerate microwave parametric amplifier device (second parametric amplifier);

a first input/output (I/O) port coupled to an input port of the first parametric amplifier and an input port of the second parametric amplifier; and

a second I/O port coupled to an input port of the first parametric amplifier and an input port of the second parametric amplifier, wherein a microwave signal (a signal of the first frequency communicated between the first I/O port and the second I/O port) is transmitted through the first parametric amplifier and the second parametric amplifier while propagating in a first direction between the first I/O port and the second I/O port and is substantially unamplified while propagating through the first parametric amplifier and the second parametric amplifier in a second direction between the second I/O port and the first I/O port, and wherein the first frequency is in a first operating bandwidth of the first Josephson device.

9. The cascade of claim 8, further comprising:

a first microwave pump injecting a first microwave drive into the first parametric amplifier at a pump frequency and a first pump phase, wherein the first microwave pump is configured to operate the first parametric amplifier at a low power gain operating point; and

a second microwave pump injecting a second microwave drive into the second parametric amplifier at the pump frequency and a second pump phase, wherein the second microwave pump is configured to operate the second parametric amplifier at the low power gain operating point.

10. The cascade of claim 8, wherein the first parametric amplifier and the second parametric amplifier are each non-degenerate three-wave mixing parametric amplifiers.

11. The cascade of claim 8, wherein the first parametric amplifier and the second parametric amplifier are each Josephson Parametric Converters (JPCs), and wherein the first parametric amplifier and the second parametric amplifier are nominally identical.

12. A method of forming a cascaded selective microwave directional amplifier (cascade), the method comprising:

fabricating a set of Josephson devices, each Josephson device in the set having a corresponding operating bandwidth at a microwave frequency, wherein different operating bandwidths have different corresponding center frequencies; and

forming a series coupling between a first josephson device from the set and an nth josephson device from the set, wherein the series coupling causes the first josephson device to amplify signals from a first frequency of a frequency multiplexed microwave signal (multiplexed signal) in a first signal flow direction through the series coupling and causes the nth josephson device to amplify signals at an nth frequency in a second signal flow direction through the series, wherein the second signal flow direction is opposite to the first signal flow direction.

13. A superconductor manufacturing system, when operated to manufacture cascaded selective microwave directional amplifiers (cascades), performs operations comprising:

fabricating a set of Josephson devices, each Josephson device in the set having a corresponding operating bandwidth at a microwave frequency, wherein different operating bandwidths have different corresponding center frequencies; and

forming a series coupling between a first josephson device from the set and an nth josephson device from the set, wherein the series coupling causes the first josephson device to amplify signals from a first frequency of a frequency multiplexed microwave signal (multiplexed signal) in a first signal flow direction through the series coupling and causes the nth josephson device to amplify signals at an nth frequency in a second signal flow direction through the series, wherein the second signal flow direction is opposite to the first signal flow direction.

14. The superconductor fabrication system of claim 13, further comprising:

(n-1) th Josephson device from the set in the series coupling, wherein n is greater than 1, wherein the (n-1) th Josephson device is included in the series coupling between the first Josephson device and the n-th Josephson device, and wherein the (n-1) th Josephson device amplifies a signal from an (n-1) th frequency of the multiplexed signal in the first signal flow direction.

15. The superconductor fabrication system of claim 13, further comprising:

(n-1) th Josephson device from the set in the series coupling, wherein n is greater than 1, wherein the (n-1) th Josephson device is included in the series coupling between the first Josephson device and the n-th Josephson device, and wherein the (n-1) th Josephson device amplifies a signal from an (n-1) th frequency of the multiplexed signal in the second signal flow direction.

16. The superconductor manufacturing system of claim 13,

wherein the series coupling causes the first Josephson device to propagate a signal at the nth frequency from the multiplexed signal without amplification in the first signal flow direction through the series coupling and causes the nth Josephson device to propagate a signal at the first frequency without amplification in the second signal flow direction through the series coupling.

17. The superconductor manufacturing system of claim 13,

wherein the series coupling causes the first Josephson device to propagate signals of all frequencies incoming to the first Josephson device from the multiplexed signal without amplification in the first signal flow direction through the series coupling except for signals of the first frequency and to selectively amplify signals of the first frequency, an

Wherein the series coupling causes the nth Josephson device to propagate signals of all frequencies incoming to the nth Josephson device from the multiplexed signal without amplification in the direction of the second signal flow through the series coupling except for the signal of the nth frequency and to selectively amplify the signal of the nth frequency.

18. The superconductor manufacturing system of claim 13,

wherein a first operating bandwidth corresponding to a microwave frequency of the first Josephson device is non-overlapping for at least some frequencies with an nth operating bandwidth corresponding to a microwave frequency of the nth Josephson device.

19. The superconductor fabrication system of claim 18,

wherein a total amplification bandwidth of the cascaded volume comprises the first operational bandwidth and the Nth operational bandwidth.

20. The superconductor fabrication system of claim 13, wherein the first josephson device of the set of josephson devices is an MPIJDA comprising:

a first non-degenerate microwave parametric amplifier device (first parametric amplifier);

a second non-degenerate microwave parametric amplifier device (second parametric amplifier);

a first input/output (I/O) port coupled to an input port of the first parametric amplifier and an input port of the second parametric amplifier; and

a second I/O port coupled to an input port of the first parametric amplifier and an input port of the second parametric amplifier, wherein a microwave signal (a signal of the first frequency communicated between the first I/O port and the second I/O port) is transmitted through the first parametric amplifier and the second parametric amplifier while propagating in a first direction between the first I/O port and the second I/O port and is substantially unamplified while propagating through the first parametric amplifier and the second parametric amplifier in a second direction between the second I/O port and the first I/O port, and wherein the first frequency is in a first operating bandwidth of the first Josephson device.

Technical Field

The present invention relates generally to devices, methods of manufacture, and systems for frequency multiplexed microwave optical amplifiers that may be used with superconducting qubits in quantum computing. More particularly, the present invention relates to a device, method and system for selectively amplifying frequency multiplexed microwave signals using cascaded multi-path interferometric josephson directional amplifiers with non-overlapping bandwidths, wherein these directional amplifiers are based on non-degenerate tri-band mixing josephson devices.

Background

In the following, unless explicitly distinguished when used, a "Q" prefix in a word of a phrase indicates that the word or phrase is referred to in a quantum computing context.

Molecular and subatomic particles follow the laws of quantum mechanics, a physical branch that explores how the physical world works at the most fundamental level. At this level, the particles behave in a strange way, taking on more than one state at the same time, and interacting with other particles very far away. Quantum computing exploits these quantum phenomena to process information.

The computer we now use is referred to as a classical computer (also referred to herein as a "legacy" computer or legacy node, or "CN"). Conventional computers use conventional processors fabricated using semiconductor materials and technologies, semiconductor memory, and magnetic or solid state memory devices, which are known as von neumann architectures. In particular, the processors in conventional computers are binary processors, i.e., operate on binary data represented by 1's and 0's.

Quantum processors (q-processors) use the odd-numbered nature of entangled qubit devices (referred to compactly herein as "qubits," a plurality of "qubits") to perform computational tasks. In the particular field of quantum mechanical manipulation, particles of matter can exist in a variety of states, such as "on" states, "off" states, and both "on" and "off" states. In the case where binary calculations using a semiconductor processor are limited to using only the ON and OFF states (equivalent to 1's and 0's in a binary code), the quantum processor utilizes the quantum states of these substances to output signals that can be used for data calculations.

Conventional computers encode information in bits. Each bit may take a value of 1 or 0. These 1's and 0's act as on/off switches that ultimately drive the computer's functions. Quantum computers, on the other hand, are based on qubits, which operate according to two key principles of quantum physics: stacking and entanglement. Superposition means that each qubit can represent both a1 and a 0. Entanglement means that qubits in a superposition can be related to each other in a non-classical way; that is, the state of one (being either a1 or a 0 or both) may depend on the state of the other, and more information may be determined when two qubits are entangled than when they are processed separately.

Using these two principles, qubits operate as more complex information processors, enabling quantum computers to function in a manner that allows them to address the difficult problems that are difficult to handle using conventional computers. IBM has successfully constructed and demonstrated the operability of quantum processors using superconducting qubits (IBM is a registered trademark of international business machines corporation in the united states and other countries).

The superconducting qubit includes a josephson junction. The josephson junction is formed by separating two thin film superconducting metal layers with a non-superconducting material. When the metal in the superconducting layers becomes superconducting, electron pairs can tunnel from one superconducting layer to the other through the non-superconducting layer, for example, by lowering the temperature of the metal to a specified cryogenic temperature. In a qubit, a josephson junction (which acts as a dispersive nonlinear inductor) is electrically coupled in parallel with one or more capacitive devices to form a nonlinear microwave oscillator. The oscillator has a resonance/transition (transition) frequency determined by the values of the inductance and capacitance in the qubit circuit. Any reference to the term "qubit" is a reference to superconducting qubit circuits employing josephson junctions, unless explicitly distinguished when used.

The information processed by the qubits is carried or transmitted in the form of microwave signals/photons in the microwave frequency range. The microwave signal is captured, processed and analyzed in order to decrypt the quantum information encoded therein. A readout circuit is a circuit coupled to a qubit for capturing, reading, and measuring the quantum state of the qubit. The output of the sensing circuit is information that can be used by the q-processor to perform calculations.

Superconducting qubits have two quantum states: i0 > and I1 >. The two states may be two energy states of the atom, for example, the ground state (| g >) and the first excited state (| e >) of a superconducting artificial atom (superconducting qubit). Other examples include spin-up and spin-down of the nuclear or electron spins, two locations of crystal defects, and two states of quantum dots. Since the system is of a quantum nature, any combination of the two states is allowed and effective.

In order for quantum computation using qubits to be reliable, quantum circuits, such as the qubits themselves, readout circuits associated with the qubits, and other parts of the quantum processor, must not change the energy state of the qubit in any significant way (e.g., by injecting or dissipating energy) or affect the relative phase between the |0> and |1> states of the qubit. This operational constraint on any circuit that operates using quantum information makes special consideration in the fabrication of semiconductor and superconducting structures for use in these circuits.

A directional microwave amplifier is a device that increases the power (amplification) of microwave light as it passes through the device in one direction (with significant forward gain in the forward direction), and passes the microwave light without any significant amplification or attenuation (with insignificant reverse gain in the reverse direction) as it attempts to pass through the device in the reverse direction. Reference herein to an "amplifier" is a reference to a directional microwave amplifier. In other words, the amplifier operates as a microwave optical power booster, and the response of the device depends on the direction of propagation of the microwave light through the device. Low noise amplifiers are used in quantum computing to amplify weak microwave signals of a quantum processor in a given flow direction while adding no or little noise to the processed signal.

A multi-path interferometric josephson directional amplifier based on a non-degenerate tri-wave mixing josephson parametric device is hereinafter referred to compactly and interchangeably as a multi-path interferometric josephson directional amplifier (MPIJDA). The MPIJDA device may be implemented as a microwave amplifier in a superconducting quantum circuit. The directional amplification in MPIJDA is generated by applying a phase gradient between the two pump tones driving the device. MPIJDA amplifies signals whose frequency lies within the bandwidth of MPIJDA substantially in the forward direction. Signals traveling in the opposite direction, whose frequencies lie within the bandwidth of MPIJDA, are amplified by a small (negligible) amount on the order of 2dB, while signals whose frequencies lie outside the band of MPIJDA in the opposite direction are transmitted with no or negligible gain. For clarity of description, amplifying a signal of any frequency in the opposite direction by MPIJDA is considered to be zero gain.

By operating the device in an amplification (photonic gain) mode, a superconducting non-degenerate three-wave mixing parametric amplifier device can be used as part of an MPIJDA. The non-degenerate tri-wave parametric amplifier may be a Josephson Parametric Converter (JPC).

The superconducting nondegenerate three-wave mixing parametric amplifier has 3 ports, i.e. through which the input frequency is f_SThrough which a microwave signal of frequency f can be input_IAnd an idler port (I) through which an idler microwave signal can be input at a frequency f_PPower of P_pAnd phase isIs provided in the microwave signal pump port (P). Superconducting nondegenerate three-wave mixing parametric amplifiers are characterized as nondegenerate because they have two modes, S and I, that differ both spatially and spectrally.

In accordance with an illustrative embodiment, two suitable representations of a non-degenerate three-wave mixing parametric amplifier are used as one component in MPIJDA, where each representation operates within a small gain limit of 3-7 dB. JPC is one such non-limiting manifestation.

In a quantum circuit, the microwave signal may comprise signals of more than one frequency. Typically, the microwave signal spans one frequency band. MPIJDA typically operates in a band of relatively narrow signal frequencies around a center frequency to which it is tuned. Illustrative embodiments recognize the need for a new amplifier design that is capable of amplifying all or some microwave signals having different frequencies, even if the frequencies of the signals lie outside the operating band of a single MPIJDA.

Disclosure of Invention

Illustrative embodiments provide a superconducting device, a method and a system for manufacturing the same. The superconducting device of one embodiment forms a cascaded selective microwave directional amplifier (cascade) comprising: a set of Josephson devices, each Josephson device in the set having a corresponding operating bandwidth at a microwave frequency, wherein different operating bandwidths have different corresponding center frequencies; and a series coupling between a first josephson device from the set and an nth josephson device from the set, wherein the series coupling causes the first josephson device to amplify a signal from a first frequency of a frequency multiplexed microwave signal (multiplexed signal) in a first signal flow direction through the series coupling and causes the nth josephson device to amplify a signal at an nth frequency in a second signal flow direction through the series coupling, wherein the second signal flow direction is opposite to the first signal flow direction.

In another embodiment, the cascade further comprises an (n-1) th josephson device from the set in the series coupling, wherein n is greater than 1, wherein the (n-1) th josephson device is included in the series coupling between the first and nth josephson devices, and wherein the (n-1) th josephson device amplifies signals from an (n-1) th frequency of the multiplexed signal in the first signal flow direction.

In another embodiment, the cascade further comprises an (n-1) th josephson device from the set in the series coupling, wherein n is greater than 1, wherein the (n-1) th josephson device is included in the series coupling between the first and nth josephson devices, and wherein the (n-1) th josephson device amplifies a signal from an (n-1) th frequency of the multiplexed signal in the second signal flow direction.

In another embodiment, the series coupling causes the first josephson device to propagate a signal at the nth frequency from the multiplexed signal without amplification in the first signal flow direction through the series coupling and causes the nth josephson device to propagate a signal at the first frequency without amplification in the second signal flow direction through the series coupling.

In another embodiment, the series coupling causes the first josephson device to propagate signals of all frequencies incoming to the first josephson device from the multiplexed signal without amplification in the first signal flow direction through the series coupling except for signals of the first frequency and to selectively amplify signals of the first frequency, and wherein the series coupling causes the nth josephson device to propagate signals of all frequencies incoming to the nth josephson device from the multiplexed signal without amplification in the second signal flow direction through the series coupling except for signals of the nth frequency and to selectively amplify signals of the nth frequency.

In another embodiment, a first operating bandwidth corresponding to a microwave frequency of the first josephson device is non-overlapping for at least some frequencies with an nth operating bandwidth corresponding to a microwave frequency of the nth josephson device.

In another embodiment, the total amplification bandwidth of the cascade comprises the first and nth operating bandwidths.

In another embodiment, the first josephson device of the set of josephson devices is an MPIJDA comprising: a first non-degenerate microwave parametric amplifier device (first parametric amplifier); a second non-degenerate microwave parametric amplifier device (second parametric amplifier); a first input/output (I/O) port coupled to an input port of the first parametric amplifier and an input port of the second parametric amplifier; and a second I/O port coupled to an input port of the first parametric amplifier and an input port of the second parametric amplifier, wherein microwave signals (signals of the first frequency communicated between the first I/O port and the second I/O port) are transmitted while propagating through the first parametric amplifier and the second parametric amplifier in a first direction between the first I/O port and the second I/O port, and is substantially unamplified while propagating through the first parametric amplifier and the second parametric amplifier in a second direction between the second I/O port and the first I/O port, and wherein the first frequency is in a first operating bandwidth of the first josephson device.

In another embodiment, the cascade further comprises a first microwave pump injecting a first microwave drive into the first parametric amplifier at a pump frequency and a first pump phase, wherein the first microwave pump is configured to operate the first parametric amplifier at a low power gain operating point; and a second microwave pump injecting a second microwave drive into the second parametric amplifier at the pump frequency and a second pump phase, wherein the second microwave pump is configured to operate the second parametric amplifier at the low power gain operating point.

In another embodiment, the first parametric amplifier and the second parametric amplifier are each non-degenerate three-wave mixing parametric amplifiers.

In another embodiment, the first parametric amplifier and the second parametric amplifier are each Josephson Parametric Converters (JPCs), and wherein the first parametric amplifier and the second parametric amplifier are nominally identical.

Drawings

The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:

FIG. 1 depicts a block diagram of an example configuration of an MPIJDA that may be used in a concatenation of stages in accordance with an illustrative embodiment;

FIG. 2 depicts another alternative configuration of MPIJDAs that may be used in a concatenation of stages in accordance with an illustrative embodiment;

FIG. 3 depicts a block diagram of an example configuration and amplification operation of a cascaded MPIJDA in accordance with an illustrative embodiment;

FIG. 4 depicts a block diagram of an example of near zero gain pass-through reverse operation of cascaded MPIJDAs in accordance with an illustrative embodiment;

fig. 5 depicts a flowchart of an example process of propagation with or without amplification of signals of all frequencies in a frequency multiplexed microwave signal using a cascaded multi-path interferometric josephson directional amplifier with non-overlapping bandwidths in accordance with an illustrative embodiment;

FIG. 6 depicts a block diagram of an example configuration and selective amplification operation of cascaded MPIJDAs in accordance with an illustrative embodiment;

FIG. 7 depicts a block diagram of an example selective amplification operation of cascaded MPIJDAs in accordance with an illustrative embodiment;

fig. 8 depicts a flowchart of an example process of near-zero gain propagation or amplification of signals of some, but not all, of the frequency multiplexed microwave signals using cascaded multi-path interferometric josephson directional amplifiers with non-overlapping bandwidths in accordance with an illustrative embodiment.

Embodiments include a method of manufacturing a superconducting device.