2007/10/31 by George I. Mias, Nigel R. Cooper, S. M. Girvin · 3 citations
Computer Science · Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Quantum Information and Cryptography #Quantum many-body systems #cond-mat.stat-mech #quant-ph
paper · pdf · doi:10.1103/physreva.77.023616
published as Phys. Rev. A77, 023616 (2008) · Revtex4: 14 pages, 10 figures. Updated version submitted to PRA with corrected typos and references. Higher resolution version available upon request
arxiv created 2007/11/12 · openalex publication_date 2008/02/14 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/30
In this paper we discuss Bose-Einstein spinor condensates for F=1 atoms in the context of 87Rb, as studied experimentally by the Stamper-Kurn group [L. E. Sadler et al., Nature (London) 443, 312 (2006)]. The dynamical quantum fluctuations of a sample that starts as a condensate of N atoms in a pure F=1, mF=0 state are described in analogy to the two-mode squeezing of quantum optics in terms of an \mathfraks\mathfraku(1,1) algebra. In this system the initial mF=0 condensate acts as a source (pump) for the creation pairs of mF=1,\ensuremath-1 atoms. We show that even though the system as a whole is described by a pure state with zero entropy, the reduced density matrix for the mF=+1 degree of freedom, obtained by tracing out the mF=\ensuremath-1,0 degrees of freedom, corresponds to a thermal state. Furthermore, these quantum fluctuations of the initial dynamics of the system provide the seeds for the formation of domains of ferromagnetically aligned spins.