# Quantum phase transition in a multiconnected Jaynes-Cummings lattice

## TL;DR

This paper investigates a multiconnected Jaynes-Cummings lattice, revealing a quantum phase transition between Mott-insulating and superfluid phases driven by competing couplings, using advanced numerical methods.

## Contribution

It provides the first detailed analysis of phase transitions in a multiconnected Jaynes-Cummings lattice with symmetry considerations and accurate critical point determination.

## Key findings

- Identified the quantum phase transition point between Mott-insulating and superfluid phases.
- Calculated correlation functions and parameters characterizing each phase.
- Demonstrated the role of coupling competition in driving phase changes.

## Abstract

The rapid progress in quantum technology enables the implementation of artificial many-body systems with correlated photons and polaritons. A multiconnected Jaynes-Cummings (MCJC) lattice can be constructed by connecting qubits and cavities alternatively. Such kind of models can be realized with superconducting qubits coupled to superconducting microwave resonators or with quantum dots coupled to optical nanocavities. We study physical properties of the one-dimensional MCJC lattice using the density-matrix renormalization group method. This model has an intrinsic symmetry between the left and right qubit-cavity couplings. The competition between these couplings may drive the ground state either to a Mott-insulating or to a superfluid phase at an integer filling. We calculate the single-particle and density-density correlation functions, the correlation lengths in the Mott-insulating phase and the Luttinger parameters in the superfluid phase, and determine accurately the critical points that separate these two phases.