Mesoscopic multipartite entanglement using atom-light interfaces

by Prof. Simone Paganelli (Grup de Física Teòrica, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain)

Wednesday 24 Jun 2009, 15:00 → 17:00 Europe/Rome

Aula 7 (Dipartimento di Fisica - Ed. E.Fermi)

It has been shown that two mesoscopic atomic samples can be entangled after the interaction with a detuned light beam and a following homodyne detection. This represents powerful method for quantum state transfer between atoms and photons, with potential implications for Quantum Information Processing. We investigate the feasibility of such methods for generation and detection of genuine multipartite entanglement between mesoscopic atomic ensembles. Our results extend in a non trivial way the EPR entanglement between two macroscopic gas samples reported experimentally in [B. Julsgaard, A. Kozhekin, and E. Polzik, Nature {\bf 413}, 400 (2001)]. We find that under realistic conditions, a second orthogonal light pulse interacting with the atomic samples after the can reverse the entangling action of the first one, leaving the samples in a separable state. This surprising result might have implications in the use of atomic ensembles as quantum repeaters.