Slow interaction quench in BCS superconductors: emergence of pre-formed pairs

Abstract

We investigate the non-equilibrium behavior of BCS superconductors subjected to slow ramps of their internal interaction strength. We identify three dynamical regimes as a function of ramp duration. For short ramp times, these systems become non-superconducting; however, fermions with opposite momenta remain paired albeit with reduced amplitudes, and the associated pair amplitude distribution is non-thermal. In this first regime, the disappearance of superconductivity is due to the loss of phase coherence between pairs. By contrast, for intermediate ramp times, superconductivity survives but the magnitude of the order parameter is reduced and presents long-lived oscillations. Finally, for long ramp times, phase coherence is almost fully retained during the slow interaction quench, and the steady-state is characterized by a thermal-like pair amplitude distribution. Using this approach, one can therefore dynamically tune the coherence between pairs in order to control the magnitude of the superconducting order parameter and even engineer a non-equilibrium state made of pre-formed pairs.

5 pages, 4 figures

References in corpus (8)

• Many-Body Physics with Ultracold Gases
• Electrodynamics of Correlated Electron Materials
• Synchronization in the BCS Pairing Dynamics as a Critical Phenomenon
• Dynamical vanishing of the order parameter in a fermionic condensate
• Quantum quench phase diagrams of an s-wave BCS-BEC condensate
• Nonequilibrium dynamics of weakly and strongly paired superconductors
• Cooper pair turbulence in atomic Fermi gases
• Spectroscopic signatures of nonequilibrium pairing in atomic Fermi gases

Cited by in corpus (2)

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