Parametric amplification and squeezing with an ac- and dc-voltage biased superconducting junction

Abstract

We theoretically investigate a near-quantum-limited parametric amplifier based on the nonlinear dynamics of quasiparticles flowing through a superconductor-insulator-superconductor junction. Photon-assisted tunneling, resulting from the combination of dc- and ac-voltage bias, gives rise to a strong parametric interaction for the electromagnetic modes reflected by the junction coupled to a transmission line. We show phase-sensitive and phase-preserving amplification, together with single- and two-mode squeezing. For an aluminum junction pumped at twice the center frequency, ω0/2π=6GHz, we predict narrow-band phase-sensitive amplification of microwaves signals to more than 20 dB, and broadband phase-preserving amplification of 20 dB over a 3-dB bandwidth of 1.2 GHz. We also predict single- and two-mode squeezing reaching more than −12dB over a 3-dB bandwidth of 5.3-GHz. Moreover, with a simple impedance-matching circuit, we demonstrate a 3-dB bandwidth reaching 4.3 GHz for 20 dB of gain. A key feature of the device is that its performance can be controlled in situ with the applied dc- and ac-voltage biases.

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