Quantum memory in an optical lattice

TL;DR

This paper investigates how the band structure in optical lattices affects quantum memory efficiency, revealing effects like superluminal velocities and enhanced coupling, which can be mitigated by tuning optical fields.

Contribution

It provides a detailed analysis of band structure effects on EIT and Raman-based quantum memories in optical lattices, highlighting how to avoid efficiency loss.

Findings

Observation of reduced and superluminal group velocities

Enhanced atom-photon coupling near band edges

Memory efficiency is compromised but can be improved by tuning fields

Abstract

Arrays of atoms trapped in optical lattices are appealing as storage media for photons, since motional dephasing of the atoms is eliminated. The regular lattice is also associated with band structure in the dispersion experienced by incident photons. Here we study the influence of this band structure on the efficiency of quantum memories based on electromagnetically induced transparency (EIT) and on Raman absorption. We observe a number of interesting effects, such as both reduced and superluminal group velocities, enhanced atom-photon coupling and anomalous transmission. These effects are ultimately deleterious to the memory efficiency, but they are easily avoided by tuning the optical fields away from the band edges.