Dynamic range and noise of the Josephson parametric converter*

We present recent progress in characterizing key properties of the Josephson parametric converter (JPC): its dynamic range and noise performance. The JPC is a phase-preserving parametric amplifier operating in the microwave regime. It is based on a ring of four Josephson junctions, which provides the non-linearity, coupled to~two microwave resonators, which increase the effective interaction between the incoming signal and this non-linearity. The JPC operates with a minimal number of modes, which simplifies its analysis, and is close to the ideal non-degenerate parametric amplifier operating at the quantum limit of noise. Besides having sufficient gain and bandwidth, a practical amplifier useful for e.g. the readout of superconducting qubits will need to exhibit a sufficiently low noise temperature and dynamic range. While dynamic range ensures that an incoming signal does not saturate the amplifier, a low noise temperature is necessary to minimally degrade signal-to-noise ratio.~