2017/10/31 by M. T. Manzoni, M. Moreno-Cardoner, A. Asenjo-Garcia +3 · 3 citations
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1088/1367-2630/aadb74
published as New Journal of Physics 20, 083048 (2018) · paper is now identical to published version
arxiv created 2018/09/04 · arxiv updated 2018/09/06
A major application for atomic ensembles consists of a quantum memory for light, in which an optical state can be reversibly converted to a collective atomic excitation on demand. There exists a well-known fundamental bound on the storage error, when the ensemble is describable by a continuous medium governed by the Maxwell-Bloch equations. The validity of this model can break down, however, in systems such as dense, ordered atomic arrays, where strong interference in emission can give rise to phenomena such as subradiance and "selective" radiance. Here, we develop a general formalism that finds the maximum storage efficiency for a collection of atoms with discrete, known positions, and a given spatial mode in which an optical field is sent. As an example, we apply this technique to study a finite two-dimensional square array of atoms. We show that such a system enables a storage error that scales with atom number Na like ∼ (log Na)2/Na2, and that, remarkably, an array of just 4 × 4 atoms in principle allows for an efficiency comparable to a disordered ensemble with optical depth of around 600.