Population trapping in a pair of periodically driven Rydberg atoms

TL;DR

This paper investigates how periodic driving and Rydberg interactions cause state-dependent population trapping in a two-atom system, revealing new mechanisms beyond single-atom models and linking trapping to dynamical stabilization.

Contribution

It introduces a general scheme to identify population trapping regions using Floquet analysis and explores the relationship between trapping, entanglement, and dynamical stabilization in Rydberg pairs.

Findings

Population trapping can occur without Floquet level crossings.

Driving-induced resonances enable control over trapping regions.

Entanglement entropy characterizes the behavior of entangled states.

Abstract

We study the population trapping extensively in a periodically driven Rydberg pair. The periodic modulation of the atom-light detuning effectively suppresses the Rabi couplings and, together with Rydberg-Rydberg interactions, leads to the state-dependent population trapping. We identify a simple yet a general scheme to determine population trapping regions using driving induced resonances, the Floquet spectrum, and the inverse participation ratio. Contrary to the single atom case, we show that the population trapping in the two-atom setup may not necessarily be associated with level crossings in the Floquet spectrum. Further, we discuss under what criteria population trapping can be related to dynamical stabilization, taking specific and experimentally relevant initial states, which include both product and the maximally entangled Bell states. The behavior of the entangled states is further characterized by the bipartite entanglement entropy.