Coherent dynamics of Rydberg atoms in cosmic microwave background radiation

TL;DR

This paper demonstrates that Rydberg atoms exposed to cosmic microwave background radiation exhibit long-lived quantum coherences, leading to observable quantum beats in fluorescence, with implications for understanding atomic dynamics in cosmic environments.

Contribution

The study provides a non-Markovian theoretical framework and an analytic model for Rydberg atom coherence dynamics induced by blackbody radiation, highlighting the potential for experimental detection.

Findings

Long-lived quantum coherences (~100 ps) observed in Rydberg atoms due to blackbody radiation

Quantum beats in fluorescence decay are a signature of these coherences

Experimental detection is challenging but feasible with CMB amplification

Abstract

Rydberg atoms excited by cold blackbody radiation are shown to display long-lived quantum coherences on timescales of tens of picoseconds. By solving non-Markovian equations of motion with no free parameters we obtain the time evolution of the density matrix, and demonstrate that the blackbody-induced temporal coherences manifest as slowly decaying (100 ps) quantum beats in time-resolved fluorescence. An analytic model shows the dependence of the coherent dynamics on the energy splitting between atomic eigenstates, transition dipole moments, and coherence time of the radiation. Experimental detection of the fluorescence signal from a trapped ensemble of $10^8$ Rydberg atom is discussed, but shown to be technically challenging at present, requiring CMB amplification somewhat beyond current practice.