Experimental observation of controllable kinetic constraints in a cold atomic gas

TL;DR

This study experimentally demonstrates how kinetic constraints influence the dynamics of a cold Rydberg gas, revealing controllable collective behaviors that align with theoretical models of many-body relaxation.

Contribution

It provides the first experimental realization of a many-body system with tunable kinetic constraints, bridging theoretical predictions and observable dynamics in cold atomic gases.

Findings

Kinetic constraints can be tailored via laser detuning.

The system exhibits correlated and anti-correlated dynamics.

Results confirm theoretical models of constrained many-body relaxation.

Abstract

Many-body systems relaxing to equilibrium can exhibit complex dynamics even if their steady state is trivial. At low temperatures or high densities their evolution is often dominated by steric hindrances affecting particle motion [1,2,3]. Local rearrangements are highly constrained, giving rise to collective - and often slow - relaxation.This dynamics can be difficult to analyse from first principles, but the essential physical ingredients are captured by idealized lattice models with so- called kinetic constraints [4]. Here we experimentally realize a many-body system exhibiting manifest kinetic constraints and measure its dynamical properties. In the cold Rydberg gas used in our experiments, the nature of the constraints can be tailored through the detuning of the excitation lasers from resonance [5,6,7,8], which controls whether the system undergoes correlated or anti- correlated dynamics. Our results confirm recent theoretical predictions [5,6], and highlight the analogy between the dynamics of interacting Rydberg gases and that of soft-matter systems.