Coherence Factors Beyond the BCS Result
Abstract
The dynamics of BCS (Bardeen-Cooper-Schrieffer) superconductors is fairly well understood due to the availability of a mean field solution for the pairing Hamiltonian, a solution which gives the quantum state of superconductor as a state of almost-free fermions interacting only with a condensate. As a result, transition probabilities may be computed, and expressed in terms of matrix elements of electron creation and annihilation operators between approximate eigenstates. These matrix elements are also called 'coherent factors'. Mean-field theory is however not sufficient to describe all eigenstates of a superconductor, a deficiency which is hardly important in (or very close) to equilibrium, but one that becomes relevant in certain out of equilibrium situations. We report here on a computation of matrix elements (coherence factors) for the pairing Hamiltonian between any 'two-arc' eigenstates in the thermodynamic limit.
Cite
@article{arxiv.1307.2701,
title = {Coherence Factors Beyond the BCS Result},
author = {Gregory Gorohovsky and Eldad Bettelheim},
journal= {arXiv preprint arXiv:1307.2701},
year = {2013}
}