Collective decoherence of cold atoms coupled to a Bose-Einstein condensate

Year: 2009

Authors: Cirone M.A., De Chiara G., Palma G.M., Recati A.

Autors Affiliation: Dipartimento di Scienze Fisiche ed Astronomiche, Università degli Studi di Palermo, via Archirafi 36, I-90123 Palermo, Italy; Grup d\’Òptica, Departament de Física, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain; NEST—CNR—INFM and Dipartimento di Scienze Fisiche ed Astronomiche, Università degli Studi di Palermo, via Archirafi 36, I-90123 Palermo, Italy; Dipartimento di Fisica, Università di Trento, CNR-INFM BEC Center, I-38050 Povo, Trento, Italy and Physik-Department, Technische Universität München, D-85748 Garching, Germany

Abstract: We examine the time evolution of cold atoms (impurities) interacting with an environment consisting of a degenerate bosonic quantum gas. The impurity atoms differ from the environment atoms, being of a different species. This allows one to superimpose two independent trapping potentials, each being effective only on one atomic kind, while transparent to the other. When the environment is homogeneous and the impurities are confined in a potential consisting of a set of double wells, the system can be described in terms of an effective spin-boson model, where the occupation of the left or right well of each site represents the two (pseudo)-spin states. The irreversible dynamics of such system is here studied exactly, i.e. not in terms of a Markovian master equation. The dynamics of one and two impurities is remarkably different in respect of the standard decoherence of the spin-boson system. In particular, we show: (i) the appearance of coherence oscillations, (ii) the presence of super and subdecoherent states that differ from the standard ones of the spin-boson model, and (iii) the persistence of coherence in the system at long times. We show that this behaviour is due to the fact that the pseudospins have an internal spatial structure. We argue that collective decoherence also prompts information about the correlation length of the environment. In a one-dimensional (1D) configuration, one can change even more strongly the qualitative behaviour of the dephasing just by tuning the interaction of the bath.


Volume: 11      Pages from: 103055  to: 103055

More Information: We acknowledge financial support from MIUR through the project PRIN 2006 \’Collective decoherence in engineered reservoirs\’ and from EUROTECH S. p. A. GDC is supported by the Spanish Ministry of Science and Innovation through the program Juan de la Cierva. AR acknowledges support also by the EuroQUAM FerMix program.
KeyWords: impurity; spin-boson model; optical lattices; ultracold atoms; Anderson localiaztion
DOI: 10.1088/1367-2630/11/10/103055

Citations: 56
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