Two-dimensional Rydberg gases and the quantum hard squares model

TL;DR

This paper investigates a 2D Rydberg atom lattice gas with strong nearest neighbor interactions, revealing a phase transition from disordered to ordered states, and connects it to the quantum hard squares model.

Contribution

It establishes an analytical description of the Rydberg gas ground state using a projected entangled pair state linked to the quantum hard squares model.

Findings

Identification of a first order phase transition.

Analytical ground state description using PEPS.

Connection between Rydberg gases and quantum hard squares.

Abstract

We study a two-dimensional lattice gas of atoms that are photo-excited to high-lying Rydberg states in which they interact via the van-der-Waals interaction. We explore the regime of dominant nearest neighbor interaction where this system is intimately connected to a quantum version of Baxter's hard squares model. We show that the strongly correlated ground state of the Rydberg gas can be analytically described by a projected entangled pair state that constitutes the ground state of the quantum hard squares model. This correspondence allows us to identify a first order phase boundary where the Rydberg gas undergoes a transition from a disordered (liquid) phase to an ordered (solid) phase.