A system includes a first superconducting wire and a second superconducting wire connected in parallel. The system includes a first current source coupled to the first superconducting wire and configured to supply a first current in response to a trigger event. The system includes a second current source coupled in series with the parallel combination of the first superconducting wire and the second superconducting wire and configured to supply a second current. The superconducting wires are configured to, while receiving the second current, operate in a superconducting state in the absence of the first current. The first superconducting wire is configured to, while receiving the second current, transition to a non-superconducting state in response to the first current. The second superconducting wire is configured to, while receiving the second current, transition to a non-superconducting state in response to the first superconducting wire transitioning to the non-superconducting state.

A system includes a first superconducting wire and a second superconducting wire connected in parallel. The system includes a first current source coupled to the first superconducting wire and configured to supply a first current in response to a trigger event. The system includes a second current source coupled in series with the parallel combination of the first superconducting wire and the second superconducting wire and configured to supply a second current. The superconducting wires are configured to, while receiving the second current, operate in a superconducting state in the absence of the first current. The first superconducting wire is configured to, while receiving the second current, transition to a non-superconducting state in response to the first current. The second superconducting wire is configured to, while receiving the second current, transition to a non-superconducting state in response to the first superconducting wire transitioning to the non-superconducting state.

A signal amplifier is distributed between first and second IC devices and includes a low-power input stage disposed within the first IC device, a bias-current source disposed within the second IC device and an output stage disposed within the second IC device. The output stage includes a resistance disposed within the second IC device and having a first terminal coupled to a drain terminal of a transistor within the input stage via a first signaling line that extends between the first and second IC devices.

A signal amplifier is distributed between first and second IC devices and includes a low-power input stage disposed within the first IC device, a bias-current source disposed within the second IC device and an output stage disposed within the second IC device. The output stage includes a resistance disposed within the second IC device and having a first terminal coupled to a drain terminal of a transistor within the input stage via a first signaling line that extends between the first and second IC devices.

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 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).

An amplifier, e.g., a low-noise amplifier, includes a field-effect transistor having a one-dimensional channel. This channel includes a semiconductor material for conducting electrons along a main direction of the channel. This direction is perpendicular to a cross-section of the channel. Dimensions of this cross-section are, together with the semiconductor material, such that the channel exhibits quantized conduction of electrons along its main direction. The amplifier further includes an electrical circuit that is configured to operate the transistor at a value of gate-to-source voltage bias corresponding to a peak value of a peak of a transconductance of the channel with respect to gate-to-source voltage bias values.

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.