Junction-free microwave two-mode radiation from a kinetic inductance nanowire

Abstract

Parametric down-conversion is a widely exploited technique in optics to produce entangled states of photons for quantum information processing and quantum sensing. In the microwave domain, devices based on Josephson junctions, such as Josephson parametric amplifiers (JPAs) and voltage-biased Josephson junctions, have been successfully utilized to generate such states. However, their high susceptibility to magnetic fields has posed challenges in many applications. Here we demonstrate the generation of two-mode squeezed states via four-wave-mixing in a superconducting nanowire resonator patterned from NbN. The NbN nanowire exhibits a strong Kerr nonlinearity, resulting in the emission of a signal-idler pair with a cross-correlation of $g^{(2)}(0) = 11.9$. Owing to the magnetic resilience and high critical temperature ($T_c$) of NbN, our microwave parametric sources based on kinetic inductance promise an expanded range of potential applications.