Adiabatic transition from a BCS superconductor to a Fermi liquid and phase dynamics

We investigate the physics of an adiabatic transition from a BCS superconductor to a Fermi liquid for an exponentially slow decreasing pairing interaction. We show that, depending on the order of the thermodynamic limit and large times, a situation can arise in which the Fermi liquid keeps a memory of the parent BCS state. Furthermore, a time inversion of the interaction, supplemented by a manipulation analogous to a spin-/photon- echo experiment, allows us to recover the parent BCS state. Moreover, we study the evolution of the order parameter phase phi in transforming the BCS superconductor to a conventional metal. Since the global phase is the conjugate variable of the density, we explicitly show how to use the dynamics of phi together with gauge invariance to build up the noninteracting chemical potential away from particle-hole symmetry. We further analyze the role of phi in restoring the gauge-invariant current response when the noninteracting Fermi liquid is approached starting from a BCS superconductor in the presence of an external vector field.

Automated summary

In this study, an adiabatic transition from a BCS superconductor to a Fermi liquid is investigated. It is found that the Fermi liquid can retain a memory of the parent BCS state and can be recovered through a specific operation. Furthermore, the evolution of the order parameter phase phi is studied and its role in restoring the noninteracting chemical potential and gauge-invariant current response is analyzed.