Quantum quench phase diagrams of an s-wave BCS-BEC condensate

E. A. Yuzbashyan, M. Dzero, V. Gurarie, and M. S. Foster
Phys. Rev. A 91, 033628 – Published 23 March 2015

Abstract

We study the dynamic response of an s-wave BCS-BEC (atomic-molecular) condensate to detuning quenches within the two-channel model beyond the weak-coupling BCS limit. At long times after the quench, the condensate ends up in one of three main asymptotic states (nonequilibrium phases), which are qualitatively similar to those in other fermionic condensates defined by a global complex order parameter. In phase I the amplitude of the order parameter vanishes as a power law, in phase II it goes to a nonzero constant, and in phase III it oscillates persistently. We construct exact quench phase diagrams that predict the asymptotic state (including the many-body wave function) depending on the initial and final detunings and on the Feshbach resonance width. Outside of the weak-coupling regime, both the mechanism and the time dependence of the relaxation of the amplitude of the order parameter in phases I and II are modified. Also, quenches from arbitrarily weak initial to sufficiently strong final coupling do not produce persistent oscillations in contrast to the behavior in the BCS regime. The most remarkable feature of coherent condensate dynamics in various fermion superfluids is an effective reduction in the number of dynamic degrees of freedom as the evolution time goes to infinity. As a result, the long-time dynamics can be fully described in terms of just a few new collective dynamical variables governed by the same Hamiltonian only with “renormalized” parameters. Combining this feature with the integrability of the underlying (e.g., the two-channel) model, we develop and consistently present a general method that explicitly obtains the exact asymptotic state of the system.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
19 More
  • Received 9 January 2015

DOI:https://doi.org/10.1103/PhysRevA.91.033628

©2015 American Physical Society

Authors & Affiliations

E. A. Yuzbashyan1, M. Dzero2, V. Gurarie3, and M. S. Foster1,4

  • 1Center for Materials Theory, Rutgers University, Piscataway, New Jersey 08854, USA
  • 2Department of Physics, Kent State University, Kent, Ohio 44240, USA
  • 3Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
  • 4Department of Physics and Astronomy, Rice University, Houston, Texas 7700, USA

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 91, Iss. 3 — March 2015

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review A

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×