A thermal and environmental noise suppressing interface circuit which is configured to operate cold and is configured to perform biasing with suppression of noise currents from room temperature noise voltages and dc coupled rf readout of a superconducting device under test with a single coaxial cable or equivalent conductor pair. The circuit is configured to suppress the propagation of thermal and environmental noises to/from sensors operating at a different temperature from its operating and control equipment while maintaining a single input-output channel, and provides for the placement of a local grounding impedance on an intercept board.

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.

An aspect includes one or more board layers. A first chip cavity is formed within the one or more board layers, wherein a first Josephson amplifier or Josephson mixer is disposed within the first chip cavity. The first Josephson amplifier or Josephson mixer comprises at least one port, each port connected to at least one connector disposed on at least one of the one or more board layers, wherein at least one of the one or more board layers comprises a circuit trace formed on the at least one of the one or more board layers.

An aspect includes one or more board layers. A first chip cavity is formed within the one or more board layers, wherein a first Josephson amplifier or Josephson mixer is disposed within the first chip cavity. The first Josephson amplifier or Josephson mixer comprises at least one port, each port connected to at least one connector disposed on at least one of the one or more board layers, wherein at least one of the one or more board layers comprises a circuit trace formed on the at least one of the one or more board layers.

An amplifier. In some embodiments, the amplifier includes a resonant circuit having a resonant frequency, a pump input, a signal input, and a signal output. The resonant circuit may include a Josephson junction connected to the pump input, the Josephson junction being a superconducting-normal-superconducting junction having two superconducting terminals and being configured to adjust the resonant frequency of the resonant circuit based on a signal received at the pump input.

An amplifier. In some embodiments, the amplifier includes a resonant circuit having a resonant frequency, a pump input, a signal input, and a signal output. The resonant circuit may include a Josephson junction connected to the pump input, the Josephson junction being a superconducting-normal-superconducting junction having two superconducting terminals and being configured to adjust the resonant frequency of the resonant circuit based on a signal received at the pump input.

A quantum computer hardware apparatus may include a first stage, which is connected to one or more signal generators, and a second stage adapted to be cooled down at a lower temperature than the first stage. Superconducting qubits are arranged in the second stage. The signal generators are configured, each, to generate radio frequency (RF) signals to drive the qubits, in operation. The apparatus may further include an intermediate stage between the first stage and the second stage, wherein the intermediate stage comprises one or more coolable filters, the latter configured for thermalizing RF signals from the signal generators. Related methods for thermalizing radio frequency signals in a quantum computer hardware apparatus are also disclosed.

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.