Observation of mesoscopic crystalline structures in a two-dimensional Rydberg gas

TL;DR

This study demonstrates the formation of mesoscopic crystalline structures in a two-dimensional Rydberg gas, revealing strong correlations and spatial order, which advances the understanding of long-range interactions in quantum many-body systems.

Contribution

The paper provides the first direct measurement of spatially ordered excitation patterns in a 2D Rydberg gas using high-resolution imaging, highlighting the emergence of mesoscopic crystals.

Findings

Observation of spatially ordered excitation patterns

Formation of mesoscopic crystalline structures

Potential for quantum simulation of long-range interactions

Abstract

The ability to control and tune interactions in ultracold atomic gases has paved the way towards the realization of new phases of matter. Whereas experiments have so far achieved a high degree of control over short-ranged interactions, the realization of long-range interactions would open up a whole new realm of many-body physics and has become a central focus of research. Rydberg atoms are very well-suited to achieve this goal, as the van der Waals forces between them are many orders of magnitude larger than for ground state atoms. Consequently, the mere laser excitation of ultracold gases can cause strongly correlated many-body states to emerge directly when atoms are transferred to Rydberg states. A key example are quantum crystals, composed of coherent superpositions of different spatially ordered configurations of collective excitations. Here we report on the direct measurement of strong correlations in a laser excited two-dimensional atomic Mott insulator using high-resolution, in-situ Rydberg atom imaging. The observations reveal the emergence of spatially ordered excitation patterns in the high-density components of the prepared many-body state. They have random orientation, but well defined geometry, forming mesoscopic crystals of collective excitations delocalised throughout the gas. Our experiment demonstrates the potential of Rydberg gases to realise exotic phases of matter, thereby laying the basis for quantum simulations of long-range interacting quantum magnets.