Quantum noise, scaling, and domain formation in a spinor Bose-Einstein condensate

Journal Article · Fri Feb 15 04:00:00 EST 2008 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.77.023616· OSTI ID:21140537

Mias, George I; Girvin, S M ^[1]; Cooper, Nigel R ^[2]

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1. Sloane Physics Laboratory, Yale University, New Haven, Connecticut 06520-8120 (United States)
2. TCM Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

In this paper we discuss Bose-Einstein spinor condensates for F=1 atoms in the context of {sup 87}Rb, 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, m{sub F}=0 state are described in analogy to the two-mode squeezing of quantum optics in terms of an su(1,1) algebra. In this system the initial m{sub F}=0 condensate acts as a source (pump) for the creation pairs of m{sub F}=1,-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 m{sub F}=+1 degree of freedom, obtained by tracing out the m{sub F}=-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.

• OSTI ID: 21140537
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 2 Vol. 77; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATOMS
BOSE-EINSTEIN CONDENSATION
DEGREES OF FREEDOM
DENSITY MATRIX
ENTROPY
FLUCTUATIONS
GROUP THEORY
NOISE
OPTICS
RUBIDIUM 87
SCALING
SPIN
SYMMETRY