Superconducting parametric interferometers for isolation and directional amplification

A device, comprising:

• a superconducting interferometric isolation circuit comprising:
• a signal input port and a signal output port, the signal input port configured to receive an input signal having a first frequency;
• a frequency conversion circuit comprising a first parametric frequency converter circuit and a second parametric frequency converter circuit, which are serially cascaded;
• and
• a delay circuit coupled in parallel with the frequency conversion circuit;
• wherein the delay circuit is configured to delay the input signal to generate a first output signal having the first frequency with a first phase, and the frequency conversion circuit is configured to generate a second output signal having the first frequency and a second phase;
• and
• wherein superconducting interferometric isolation circuit is configured to constructively combine the first output signal and the second output signal at the signal output port to generate an output signal having the first frequency, and to provide isolation of the signal input port from a signal which is present at the signal output port.

A device, comprising:

• a superconducting parametric interferometric circuit comprising:
• a first hybrid coupler and a second hybrid coupler, the first hybrid coupler comprising a signal input port which is configured to receive an input signal having a first frequency, and the second hybrid coupler comprising a signal output port;
• and
• a first parametric mixing circuit and a second parametric mixing circuit, which are coupled in parallel between the first hybrid coupler and the second hybrid coupler;
• wherein the first hybrid coupler is configured to divide the input signal into a first input signal having the first frequency, and a second input signal having the first frequency;
• wherein the first parametric mixing circuit is configured to convert the first input signal to a first output signal having a second frequency, and the second parametric mixing circuit is configured to convert the second input signal to a second output signal having the second frequency;
• and
• wherein the second hybrid coupler is configured to combine the first output signal and the second output signal at the signal output port to generate an output signal having the second frequency.

A device, comprising:

• a superconducting interferometric isolation circuit comprising:
• a first hybrid coupler and a second hybrid coupler, the first hybrid coupler comprising a signal input port which is configured to receive an input signal having a first frequency, and the second hybrid coupler comprising a signal output port;
• and
• a frequency conversion circuit comprising a first parametric frequency converter circuit and a second parametric frequency converter circuit, which are serially cascaded;
• and
• a delay circuit which is coupled in parallel with the frequency conversion circuit between the first hybrid coupler and the second hybrid coupler;
• wherein the delay circuit is configured to group delay the input signal to generate a first output signal having the first frequency with a first phase, and the frequency conversion circuit is configured to generate a second output signal having the first frequency and a second phase;
• and
• wherein the second hybrid coupler is configured to constructively combine the first output signal and the second output signal at the signal output port to generate an output signal having the first frequency.

A system, comprising:

• a quantum processor comprising quantum bits;
• a readout signal path configured to transmit signals that are readout from one or more of the quantum bits of the quantum processor, the readout signal path comprising a superconducting parametric interferometric circuit, which comprises:
• a signal input port and a signal output port, the signal input port configured to receive an input signal having a first frequency, the input signal comprising a readout signal of at least one quantum bit;
• a first parametric mixing circuit and a second parametric mixing circuit coupled in parallel between the signal input port and the signal output port;
• wherein the first parametric mixing circuit is configured to convert the input signal to a first output signal having a second frequency, and the second parametric mixing circuit is configured to convert the input signal to a second output signal having the second frequency;
• and
• wherein superconducting parametric interferometric circuit is configured to constructively combine the first output signal and the second output signal at the signal output port to generate an output signal having the second frequency, and to provide isolation of the signal input port from a signal which is present at the signal output port.