Observation of the Crossover from Photon Ordering to Delocalization in Tunably Coupled Resonators

TL;DR

This study demonstrates a transition from photon ordering to delocalization in a tunably coupled resonator system, revealing insights into non-equilibrium many-body phases relevant for quantum simulation.

Contribution

We experimentally observe a crossover in photon states controlled by tunable coupling, advancing understanding of non-equilibrium phases in driven-dissipative quantum systems.

Findings

Observed a crossover from ordered to delocalized photon states

Controlled photon hopping via parametric flux modulation

Coupling scheme is robust to frequency disorder

Abstract

Networks of nonlinear resonators offer intriguing perspectives as quantum simulators for non-equilibrium many-body phases of driven-dissipative systems. Here, we employ photon correlation measurements to study the radiation fields emitted from a system of two superconducting resonators, coupled nonlinearly by a superconducting quantum interference device (SQUID). We apply a parametrically modulated magnetic flux to control the linear photon hopping rate between the two resonators and its ratio with the cross-Kerr rate. When increasing the hopping rate, we observe a crossover from an ordered to a delocalized state of photons. The presented coupling scheme is intrinsically robust to frequency disorder and may therefore prove useful for realizing larger-scale resonator arrays.