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 bandpass parametric amplifier circuit includes a plurality of unit cells. At least one unit cell includes a first inductor having a first node coupled to a center conductor and a second node coupled to ground. There is a first capacitor having a first node coupled to the center conductor and a second node coupled to ground. There is a second inductor having a first node coupled to the center conductor. A second capacitor has a first node coupled to a second node of the second inductor. The second capacitor and the second inductor are in series with the center conductor.

A bandpass parametric amplifier circuit includes a plurality of unit cells. At least one unit cell includes a first inductor having a first node coupled to a center conductor and a second node coupled to ground. There is a first capacitor having a first node coupled to the center conductor and a second node coupled to ground. There is a second inductor having a first node coupled to the center conductor. A second capacitor has a first node coupled to a second node of the second inductor. The second capacitor and the second inductor are in series with the center conductor.

A system includes a quantum processor includes a plurality of qubits. For each qubit, there is a circulator operative to receive a control signal and an output signal from the qubit. An isolator is coupled to an output of the circulator. A quantum-limited amplifier is coupled to an output of the isolator and configured to provide an output of the qubit. A multiplexor (MUX) is configured to frequency multiplex the outputs of at least two of the plurality of qubits as a single output of the quantum processor.

A system includes a quantum processor includes a plurality of qubits. For each qubit, there is a circulator operative to receive a control signal and an output signal from the qubit. An isolator is coupled to an output of the circulator. A quantum-limited amplifier is coupled to an output of the isolator and configured to provide an output of the qubit. A multiplexor (MUX) is configured to frequency multiplex the outputs of at least two of the plurality of qubits as a single output of the quantum processor.

An integrated qubit readout circuit is presented, which includes a superconducting parametric amplifier, a circuit board arranged to mount the superconducting parametric amplifier, a circulator mounted on the circuit board and connected to the superconducting parametric amplifier, wherein the circulator comprises a termination port electrically connected to a termination resistor arranged to terminate a pump tone received by the superconducting parametric amplifier, and wherein the termination resistor is mounted on the circuit board.

An integrated qubit readout circuit is presented, which includes a superconducting parametric amplifier, a circuit board arranged to mount the superconducting parametric amplifier, a circulator mounted on the circuit board and connected to the superconducting parametric amplifier, wherein the circulator comprises a termination port electrically connected to a termination resistor arranged to terminate a pump tone received by the superconducting parametric amplifier, and wherein the termination resistor is mounted on the circuit board.

A traveling wave parametric amplifier involving a series of Josephson junctions is disclosed. Devices and systems incorporating traveling wave parametric amplifiers, and methods of using and fabricating traveling wave parametric amplifiers are also disclosed.

A traveling wave parametric amplifier involving a series of Josephson junctions is disclosed. Devices and systems incorporating traveling wave parametric amplifiers, and methods of using and fabricating traveling wave parametric amplifiers are also disclosed.