A technique relates to a superconducting device. A first mixing device has a first mixing port and a second mixing port. A second mixing device has another first mixing port and another second mixing port. The first and second mixing devices are superconducting nondegenerate three-wave mixing devices. The first mixing port and the another first mixing port are configured to couple to a first coupler. The second mixing port and the another second mixing port are configured to couple to a second coupler.

A technique relates to a superconducting device. A first mixing device has a first mixing port and a second mixing port. A second mixing device has another first mixing port and another second mixing port. The first and second mixing devices are superconducting nondegenerate three-wave mixing devices. The first mixing port and the another first mixing port are configured to couple to a first coupler. The second mixing port and the another second mixing port are configured to couple to a second coupler.

A cascading selective microwave isolator (cascade) includes a set of Josephson devices, each Josephson device in the set having a corresponding operating bandwidth of microwave frequencies. Different operating bandwidths have different corresponding center frequencies. A series coupling is formed between first Josephson device from the set and an n.sup.th Josephson device from the set. The series coupling causes the first Josephson device to isolate a signal at a first frequency from a frequency multiplexed microwave signal (multiplexed signal) in a first signal flow direction through the series coupling and the n.sup.th Josephson device to isolate a signal of an n.sup.th frequency in a second signal flow direction through the series, where the second signal flow direction is opposite of the first signal flow direction.

A technique relates to a superconducting device. A first mixing device has a first mixing port and a second mixing port. A second mixing device has another first mixing port and another second mixing port. The first and second mixing devices are superconducting nondegenerate three-wave mixing devices. The first mixing port and the another first mixing port are configured to couple to a first coupler. The second mixing port and the another second mixing port are configured to couple to a second coupler.

A technique relates to a superconducting device. A first mixing device has a first mixing port and a second mixing port. A second mixing device has another first mixing port and another second mixing port. The first and second mixing devices are superconducting nondegenerate three-wave mixing devices. The first mixing port and the another first mixing port are configured to couple to a first coupler. The second mixing port and the another second mixing port are configured to couple to a second coupler.

A Josephson parametric converter is provided. The Josephson parametric converter includes a multi-Josephson junction ring modulator having arrays of Josephson junctions arranged in a ring configuration with ring nodes inter-dispersed between the arrays and a center node inter-connecting the ring nodes. The Josephson parametric also includes resonators formed from capacitors that shunt the multi-Josephson junction ring modulator and enable respective modes of the Josephson parametric converter.

A Josephson parametric converter is provided. The Josephson parametric converter includes a multi-Josephson junction ring modulator having arrays of Josephson junctions arranged in a ring configuration with nodes inter-dispersed between the arrays. The Josephson parametric converter includes resonators formed from capacitors that shunt the multi-Josephson junction ring modulator and enable respective modes of the Josephson parametric converter.

According to an example aspect of the present invention, there is provided an isolating amplifier apparatus comprising a first 2?2 hybrid coupler and a second 2?2 hybrid coupler, each 2?2 hybrid coupler having a first input port, a second input port, a first output port and a second output port, a first travelling wave parametric amplifier, TWPA, comprising an input connected to the first output port of the first 2?2 hybrid coupler and an output connected to the first input port of the second 2?2 hybrid coupler, and a second travelling wave parametric amplifier, TWPA, comprising an input connected to the second output port of the first 2?2 hybrid coupler and an output connected to the second input of the second 2?2 hybrid coupler.

A Josephson parametric converter is provided. The Josephson parametric converter includes a multi-Josephson junction ring modulator having arrays of N Josephson junctions arranged in a ring configuration with ring nodes inter-dispersed between the arrays. The multi-Josephson junction ring modulator further has a center node inter-connecting the ring nodes. N is an integer having a value greater than one. The Josephson parametric also includes a first and a second resonator formed from lumped-element capacitors that shunt the multi-Josephson junction ring modulator and respectively enable a first and a second mode of the Josephson parametric converter.

A Josephson parametric converter is provided. The Josephson parametric converter includes a multi-Josephson junction ring modulator having arrays of N Josephson junctions arranged in a ring configuration with nodes inter-dispersed between the arrays. N is an integer having a value greater than one. The Josephson parametric converter includes a first and a second resonator formed from lumped-element capacitors that shunt the multi-Josephson junction ring modulator and respectively enable a first and a second mode of the Josephson parametric converter.