An optical conveyor belt for single neutral atoms.pdf

a r X i v : q u a n t - p h / 0 1 0 7 0 2 9 v 1 5 J u l 2 0 0 1 An optical conveyor belt for single neutral atoms Dominik Schrader, Stefan Kuhr, Wolfgang Alt, Martin Mu?ller, Victor Gomer, and Dieter Meschede Institut fu?r Angewandte Physik, Universita?t Bonn Wegelerstr. 8, D-53115 Bonn, Germany e-mail: schrader@iap.uni-bonn.de July 5, 2001 Abstract Using optical dipole forces we have realized controlled transport of a single or any desired small num- ber of neutral atoms over a distance of a centimeter with sub-micrometer precision. A standing wave dipole trap is loaded with a prescribed number of cesium atoms from a magneto-optical trap. Mutual detuning of the counter- propagating laser beams moves the interference pattern, allowing us to accelerate and stop the atoms at prese- lected points along the standing wave. The transporta- tion efficiency is close to 100 %. This optical ”single- atom conveyor belt” represents a versatile tool for fu- ture experiments requiring deterministic delivery of a prescribed number of atoms on demand. PACS: 32.80.Lg, 32.80.Pj, 42.50.Vk Quantum engineering of microscopic systems requires manipulation of all degrees of freedom of isolated atomic particles. The most advanced experiments are imple- mented with trapped chains of ions [1,2,3]. Neutral atoms are more difficult to control because of the weaker inter- action of induced electric or paramagnetic dipoles with inhomogeneous electromagnetic fields. Optical dipole traps [4] could provide a level of control similar to ion traps, since they store neutral atoms in a nearly conservative potential with long coherence times [5]. The variety of different dipole traps allows for an individual design, de- pending on the specific experimental demands [6]. Here we use a time-varying standing wave optical dipole trap to displace atoms by macroscopic distances on the order of a centimeter with sub-micrometer pre- cision [7]. A similar technique of moving optical lattices has been applied