Shapiro Resonances in Mechanically Modulated Exciton-Polariton Josephson Junctions

We experimentally investigate the dynamics of Josephson junctions between two confined exciton-polariton condensates when periodically modulated via self-induced GHz mechanical oscillations. We show that the energy detuning between the condensates displays a plateau behavior akin to the Shapiro steps when it matches the modulation quantum. At the step, massive tunneling of particles occurs, featuring Shapiro-like spikes with an asymmetric shape determined by the nonlinearities and gain present in this quantum driven-dissipative system.