Interference of atoms and formation of atomic spatial arrays in light fields

Veniamin P. Chebotayev, B. Dubetsky, A. P. Kazantsev +1 more

Sebastian Wolf, Julian Wechs, Joachim von Zanthier +1 more

We observe interference in the light scattered from trapped ^{40}Ca^{+} ion crystals. By varying the intensity of the excitation laser, we study the influence of elastic and inelastic scattering on the visibility of the fringe pattern and discriminate its effect from that of the ion temperature and wave-packet localization. In this way we determine the complex degree of coherence and the mutual coherence of light fields produced by individual atoms. We obtain interference fringes from crystals consisting of two, three, and four ions in a harmonic trap. Control of the trapping potential allows for the adjustment of the interatomic distances and thus the formation of linear arrays of atoms serving as a regular grating of microscopic scatterers.

B Ya Dubetskiĭ, A. P. Kazantsev, V. P. Chebotaev +1 more

D. R. Meacher

In an optical lattice the interaction of an atomic gas with a spatially modulated light field is exploited to damp the atomic motion and then to trap the slowly moving atoms on a regular array of points associated with particular local states of the light field. The result of this process is the formation, from the initially cold but disordered gas, of a structure reminiscent of those found in solid-state crystalline materials. The study of these novel, optically-bound media necessitates the introduction to the description of the atom-light interaction of concepts more usually encountered in solid-state physics and promises to shed new light on the nature of atom-light interactions. Additionally, it provides a new means for the precise and highly parallel manipulation of atoms and a novel test-bed for some fundamental problems in physics.

Marco T. Manzoni, Maria Moreno-Cardoner, Ana Asenjo-Garcı́a +3 more

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. However, these equations are semi-phenomenological, as they treat emission of the atoms into other directions other than the mode of interest as being independent. On the other hand, in systems such as dense, ordered atomic arrays, atoms interact with each other strongly and spatial interference of the emitted light might be exploited to suppress emission into unwanted directions, thereby enabling improved error bounds. Here, we develop a general formalism that fully accounts for spatial interference, and which finds the maximum storage efficiency for a single photon with known spatial input mode into a collection of atoms with discrete, known positions. 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 N a like , and that, remarkably, an array of just 4 × 4 atoms in principle allows for an error of less than 1%, which is comparable to a disordered ensemble with an optical depth of around 600.

Н. І. Жукова, A. P. Kazantsev, É. F. Kazantsev +1 more