Hydrodynamic theory of quantum fluctuating superconductivity

TL;DR

This paper develops a hydrodynamic framework to describe transport in quantum phase-disordered superconductors, deriving conductivity properties and resonances influenced by supercurrent relaxation mechanisms.

Contribution

It introduces a quantum hydrodynamic theory for phase-disordered superconductors, including a new derivation of flux flow resistance and analysis of supercyclotron resonances.

Findings

Conductivity characterized by a Drude-like peak with width from supercurrent relaxation rate.

Derived a formula for supercurrent relaxation rate via Coulomb interactions.

Identified a hydrodynamic supercyclotron resonance in time-reversal symmetry breaking regimes.

Abstract

A hydrodynamic theory of transport in quantum mechanically phase-disordered superconductors is possible when supercurrent relaxation can be treated as a slow process. We obtain general results for the frequency-dependent conductivity of such a regime. With time-reversal invariance, the conductivity is characterized by a Drude-like peak, with width given by the supercurrent relaxation rate. Using the memory matrix formalism, we obtain a formula for this width (and hence also the dc resistivity) when the supercurrent is relaxed by short range Coulomb interactions. This leads to a new -- effective field theoretic and fully quantum -- derivation of a classic result on flux flow resistance. With strong breaking of time-reversal invariance, the optical conductivity exhibits what we call a `hydrodynamic supercyclotron' resonance. We obtain the frequency and decay rate of this resonance for the case of supercurrent relaxation due to an emergent Chern-Simons gauge field. The supercurrent decay rate in this `topologically ordered superfluid vortex liquid' is determined by the conductivities of the normal component of the liquid. Our work gives a controlled framework for low temperature metallic phases arising from phase-disordered superconductivity.