Observation of Collective Bistability in a nonlinear resonator array

Dissipative phase transitions are abrupt shifts in a system's steady state caused by tuning a control parameter. Previous studies have mainly focused on first and second-order transitions in single Kerr resonators. In this work, we present the first experimental and theoretical study on collective first and second-order phase transitions. Our device comprises an array of 21 nearest-neighbor coupled superconducting resonators. Each resonator consists of 10 Josephson junctions as the non-linear inductor, shunted by a capacitive element. We observe a collective first-order dissipative phase transition in the 21 modes of the array when any single resonator is driven close to its resonance frequency and, both collective first and second phase transitions with two drive frequencies that sum to twice the resonator frequencies via 4-wave mixing. This study provides new insights into the collective non-linear dynamics of coupled Kerr resonators, usual frameworks for studying many-body physics, and implementing quantum simulation and long-range interactions.