Quantum phase transition in a multi-connected superconducting Jaynes-Cummings lattice

TL;DR

This paper introduces a multi-connected Jaynes-Cummings lattice model in superconducting circuits, revealing a reentrant Mott insulator-superfluid phase transition, and proposes a simple experimental protocol to observe this phenomenon.

Contribution

It presents a symmetric multi-connected Jaynes-Cummings lattice model exhibiting a reentrant phase transition, with a practical scheme for experimental realization using superconducting circuits.

Findings

The model shows a Mott insulator-superfluid-Mott insulator phase transition.

Phase diagrams confirm the incompressibility of the Mott phase.

Only two operations are needed to demonstrate the phase transition experimentally.

Abstract

The connectivity and tunability of superconducting qubits and resonators provide us with an appealing platform to study the many-body physics of microwave excitations. Here we present a multi-connected Jaynes-Cummings lattice model which is symmetric with respect to the nonlocal qubit-resonator couplings. Our calculation shows that this model exhibits a Mott insulator-superfluid-Mott insulator phase transition, featured by a reentry to the Mott insulator phase, at commensurate filling. The phase diagrams in the grand canonical ensemble are also derived, which confirm the incompressibility of the Mott insulator phase. Different from a general-purposed quantum computer, it only requires two operations to demonstrate this phase transition: the preparation and the detection of the commensurate many-body ground state. We discuss the realization of these operations in a superconducting circuit.