A four-wave mixing transmission line (3) including: an input (15, 17, 19) arranged to receive: a first pump signal (7a) having a first pump frequency; a second pump signal (7b), having a second pump frequency, different to the first pump frequency; and an input signal to be amplified (5); a non-linear medium (3a) having an intrinsic dispersion relationship, the medium (3a) arranged to allow interaction between the input signal (5), the first pump signal (7a) and the second pump signal (7b), such that the input signal (5) is amplified and an idler signal (9) is generated and amplified; and a plurality of dispersion control elements (31, 33, 49), the dispersion control elements (31, 33, 49) arranged to alter the dispersion relationship of the medium (3a) to diverge from the intrinsic dispersion relationship at one or more frequencies, such that the total phase difference between the input signal, (5) the first pump signal (7a), the second pump signal (7b) and the idler signal (9) is kept at zero or substantially zero as the first pump signal (7a), the second pump signal (7b), the input signal (5) and the idler signal (9) propagate down the transmission line (3).

A four-wave mixing transmission line (3) including: an input (15, 17, 19) arranged to receive: a first pump signal (7a) having a first pump frequency; a second pump signal (7b), having a second pump frequency, different to the first pump frequency; and an input signal to be amplified (5); a non-linear medium (3a) having an intrinsic dispersion relationship, the medium (3a) arranged to allow interaction between the input signal (5), the first pump signal (7a) and the second pump signal (7b), such that the input signal (5) is amplified and an idler signal (9) is generated and amplified; and a plurality of dispersion control elements (31, 33, 49), the dispersion control elements (31, 33, 49) arranged to alter the dispersion relationship of the medium (3a) to diverge from the intrinsic dispersion relationship at one or more frequencies, such that the total phase difference between the input signal, (5) the first pump signal (7a), the second pump signal (7b) and the idler signal (9) is kept at zero or substantially zero as the first pump signal (7a), the second pump signal (7b), the input signal (5) and the idler signal (9) propagate down the transmission line (3).

A system and method are disclosed for a superconducting traveling-wave parametric amplifier (TWPA) with improved control and performance. In a preferred embodiment, the amplifier comprises an integrated array of symmetric rf-SQUIDs in a transmission line structure. A device was fabricated using niobium superconducting integrated circuits, and confirmed predicted performance, with a maximum gain up to 17 dB and a bandwidth of 4 GHz. A similar device can be applied as a low-noise, low-dissipation microwave amplifier for output from a superconducting quantum computer, or as a preamplifier, switch, or frequency converter for a sensitive microwave receiver, or as an output amplifier for a frequency-multiplexed superconducting detector array.

A system and method are disclosed for a superconducting traveling-wave parametric amplifier (TWPA) with improved control and performance. In a preferred embodiment, the amplifier comprises an integrated array of symmetric rf-SQUIDs in a transmission line structure. A device was fabricated using niobium superconducting integrated circuits, and confirmed predicted performance, with a maximum gain up to 17 dB and a bandwidth of 4 GHz. A similar device can be applied as a low-noise, low-dissipation microwave amplifier for output from a superconducting quantum computer, or as a preamplifier, switch, or frequency converter for a sensitive microwave receiver, or as an output amplifier for a frequency-multiplexed superconducting detector array.

A traveling wave kinetic inductance parametric amplifier is presented. The amplifier includes a microstrip structure defining a parallel plate capacitor element formed by first and second electrically conductive layers spaced by a dielectric spacer layer. The first electrically conductive layer is made of superconducting material composition having desirably high kinetic inductance and being configured as a nanoscale thickness strip.

A radio frequency (RF) wave generator includes a nonlinear transmission line and a pulse generator. The nonlinear transmission line has in order an input section, a magnetic section, and an output section. The magnetic section includes a nonlinear magnetic material. The pulse generator is configured to provide an input pulse to the input section which is converted to an RF wave by the nonlinear transmission line. A waveform of the input pulse is such that the generated RF wave is parametrically amplified.

A traveling wave superconducting parametric amplifier is provided. The traveling wave superconducting parametric amplifier includes a chain of superconducting elements having a nonlinear kinetic inductance connected in series, said superconducting elements being deposited on a substrate. The traveling wave superconducting parametric amplifier also includes a dielectric layer of sub-micrometer thickness deposited on the substrate and covering said superconducting elements, and a conductive layer forming a ground plane deposited on top of the dielectric layer, the superconducting elements and the ground plane forming a microstrip-type transmission line. A method for producing such a traveling wave parametric amplifier is also provided.

A topologically-protected traveling-wave amplifier includes resonators arranged in a two-dimensional array defining a periphery including a first edge. An output line is coupled to an output resonator disposed along the first edge spaced from an input resonator coupled to an output line. A synthetic gauge field generator associated with the resonators provides a topologically-protected edge state corresponding to propagation along the periphery in a propagation direction from the input resonator along the first edge to the output resonator. A parametric driving element creates pairs of photons in the edge state and amplifies a signal propagating along the first edge in the propagation direction. A signal incident from the input line propagates in the propagation direction along the first edge while being amplified and is detected at the output line as an amplified signal. A signal incident from the output line is attenuated before emerging at the input resonator.

A topologically-protected traveling-wave amplifier includes resonators arranged in a two-dimensional array defining a periphery including a first edge. An output line is coupled to an output resonator disposed along the first edge spaced from an input resonator coupled to an output line. A synthetic gauge field generator associated with the resonators provides a topologically-protected edge state corresponding to propagation along the periphery in a propagation direction from the input resonator along the first edge to the output resonator. A parametric driving element creates pairs of photons in the edge state and amplifies a signal propagating along the first edge in the propagation direction. A signal incident from the input line propagates in the propagation direction along the first edge while being amplified and is detected at the output line as an amplified signal. A signal incident from the output line is attenuated before emerging at the input resonator.

According to some aspects, a quantum circuit is provided including a plurality of non-linear circuit elements coupled together in series and in parallel, such that at least two of the circuit elements are coupled together in series and at least two of the circuit elements are coupled together in parallel, wherein the quantum circuit is configured to act as an amplifier.