Dynamical equilibration across a quenched phase transition in a trapped quantum gas

Year: 2018

Authors: Liu IK., Donadello S., Lamporesi G., Ferrari G., Gou SC., Dalfovo F., Proukakis NP.

Autors Affiliation: Newcastle Univ, Sch Math Stat & Phys, Joint Quantum Ctr JQC Durham Newcastle, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England; Natl Changhua Univ Educ, Dept Phys, Changhua 50058, Taiwan; Natl Changhua Univ Educ, Grad Inst Photon, Changhua 50058, Taiwan; Univ Trento, INO CNR BEC Ctr, I-38123 Trento, Italy; Univ Trento, Dipartimento Fis, I-38123 Trento, Italy.

Abstract: The formation of an equilibrium state from an uncorrelated thermal one through the dynamical crossing of a phase transition is a central question of quantum many-body physics. During such crossing, the system breaks its symmetry by establishing numerous uncorrelated regions separated by spontaneously generated defects, whose emergence obeys a universal scaling law with quench duration. The ensuing re-equilibrating or coarse-graining stage is governed by the evolution and interactions of such defects under system-specific and external constraints. We perform a detailed numerical characterisation of the entire non-equilibrium process associated with the Bose-Einstein condensation phase transition in a three-dimensional gas of ultracold atoms, addressing subtle issues and demonstrating the quench-induced decoupling of condensate atom number and coherence growth during the re-equilibration process. Our findings agree, in a statistical sense, with experimental observations made at the later stages of the quench, and provide valuable information and useful dynamical visualisations in currently experimentally inaccessible regimes.

Journal/Review: COMMUNICATIONS PHYSICS

Volume: 1      Pages from: 24-1  to: 24-12

More Information: N.P.P. and I.-K.L. acknowledge discussions with Jerome Beugnon, Paolo Comaron, Leticia Cugliandolo, Jean Dalibard, Zoran Hadzibabic, Fabrizio Larcher, Nir Navon and Rob Smith during the course of the project, computational assistance by Kean Loon Lee and George Stagg and help with diagonalising huge matrices from T.-M. Huang and W.-W. Lin. This work w as supported by the Taiwan MOST 103-2112-M-018-002-MY3 grant, the UK EPSRC Grant No. EP/K03250X/1, the QUIC grant of the Horizon 2020 FET program, Provincia Autonoma di Trento, the National Center of Theoretical Sciences, Taiwan and the QuantERA ERA-NET cofund project NAQUAS.
KeyWords: Spontaneous Symmetry-breaking; String Formation; Condensation; Coherence; Emergence; Vortices; Growth
DOI: 10.1038/s42005-018-0023-6

Citations: 44
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