A parametrically programmable coupled oscillator network implemented using microwave superconducting circuits

There is growing interest in networks of coupled optical parametric oscillators (OPOs) for their application as a Coherent Ising Machine (CIM). Despite their success, quantum effects are obscured in these OPO networks due to their large critical photon numbers. We introduce a new superconducting platform for implementing CIMs – the parametrically programmable coupled oscillator machine. Our platform can: 1) implement a variety of Ising couplings in a programmable way, 2) tune its nonlinear to linear loss ratio over a broad range, 3) achieve single-digit critical photon numbers, and 4) be read out easily through microwave lines. The crucial component in our proposal is the Asymmetrically Threaded SQUID (ATS). Unlike most Josephson junction-based circuits that rely on four-wave mixing, the ATS enables the three-wave mixing interaction typically used by OPOs. I will discuss our proposal for using one ATS coupled to many microwave resonators to study how quantum fluctuations change behaviors in CIMs, as well as early experimental results.