Strongly interacting fluids in a Bose-Hubbard circuit

Synthetic photonic systems offer a robust platform for exploring the rich physics of strongly interacting and highly correlated quantum materials. We build a strongly interacting Bose Hubbard lattice with tunable on-site frequencies by capacitively coupling a 1D lattice of transmon qubits, where the anharmonicity of the transmons provides the effective onsite interaction. Individual readout resonators allow measurement access to each site and simultaneous measurements generate correlated density information about the quantum many-body state. Using these tools we study the static and dynamical properties of an adiabatically prepared fluid. We characterize the transition from the diabatic to adiabatic regime, quantify the long-range order of the lattice with two-body density correlations, and probe lattice entanglement by measuring the average purity of the lattice state. We also investigate transport properties by locally modulating the lattice potential and measuring the spectral response, probing the density of states of the strongly interacting fluid.