Coherent control in atomic chains: to trap and release a traveling excitation

TL;DR

This paper presents a protocol for controlling the propagation of dark states in atomic chains, enabling the trapping and releasing of excitations with minimal dissipation through external field manipulation.

Contribution

It introduces a novel method for dynamical dispersion engineering in atomic chains using spatially-varying control fields, offering an alternative to electromagnetically-induced transparency.

Findings

Dark states support dissipation-protected propagating spin waves.

Control over group velocity of spin waves is achieved via external fields.

Excitations can be stored and released adiabatically without loss.

Abstract

We introduce a protocol for dynamical dispersion engineering in an atomic chain consisting of an ordered array of multi-level atoms with subwavelength lattice constant. This chain supports dark states that are protected from dissipation in the form of photon emission and can be understood as propagating spin waves traveling along the array. By using an external control field with a spatially-varying elliptical polarization we correlate internal and external degrees of freedom of the array in a controllable way. The coherent control over the atomic states translates into control over the group velocity of the spin waves. A traveling excitation can be stored and released without dissipation by adiabatically changing the control field amplitude. This protocol is an alternative to the more conventional electromagnetically-induced transparency, and exemplifies the rich physics born of the interplay between coherent control and correlated decay.