Squeezed-field path-integral description of BCS superconductors
Abstract
We develop a squeezed-field path-integral representation for BCS superconductors utilizing a generalized completeness relation of squeezed-fermionic coherent states. We derive a Grassmann path integral of fermionic quasiparticles that explicitly includes the collective degrees of freedom of the order-parameter dynamics governed by the classical Anderson pseudospin model. Based on this method, we analyze the spectral function of the single-particle excitations, and show that the squeezed-field path integral for the BCS Hamiltonian describes a bosonic sideband branch that corresponds to the Higgs amplitude mode of BCS superconductors, in addition to reproducing the quasiparticle and quasihole excitation branches described by the BCS mean-field approximation.
Cite
@article{arxiv.2102.12348,
title = {Squeezed-field path-integral description of BCS superconductors},
author = {Kazuma Nagao and Dapeng Li and Ludwig Mathey},
journal= {arXiv preprint arXiv:2102.12348},
year = {2022}
}
Comments
14 pages, 4 figures