## Abstract

We calculated the optical conductivity $\sigma(T,\Omega)$ of a gas of

Bogoliubov quasiparticles (BQP) from their Green's function and the

Kubo formula. We compare with corresponding normal state (N) and

superconducting state (SC) results. The superconducting case includes

the dynamic response of the condensate through additional contributions

to the Kubo formula involving the Gor'kov anomalous Green's function.

The differences in the optical scattering rate are largest just

above the optical gap and become progressively smaller as the photon

energy is increased or the temperature is raised. Our results are

compared with those obtained using a recently advocated phenomenological

procedure for eliminating the effect of the condensate.\cite{dord2014}

The $\delta$-function contribution at zero photon energy, proportional to

the superfluid density, is dropped in the real part of the conductivity

$[\sigma_1(T,\Omega)]$ and its Kramers-Kronig transform is subtracted from

the imaginary part $\sigma_2(T,\Omega)$. This results in deviations from

our BQP and superconducting state optical scattering rates even in the

region where these have merged and are, in addition, close to the normal

state result.

Bogoliubov quasiparticles (BQP) from their Green's function and the

Kubo formula. We compare with corresponding normal state (N) and

superconducting state (SC) results. The superconducting case includes

the dynamic response of the condensate through additional contributions

to the Kubo formula involving the Gor'kov anomalous Green's function.

The differences in the optical scattering rate are largest just

above the optical gap and become progressively smaller as the photon

energy is increased or the temperature is raised. Our results are

compared with those obtained using a recently advocated phenomenological

procedure for eliminating the effect of the condensate.\cite{dord2014}

The $\delta$-function contribution at zero photon energy, proportional to

the superfluid density, is dropped in the real part of the conductivity

$[\sigma_1(T,\Omega)]$ and its Kramers-Kronig transform is subtracted from

the imaginary part $\sigma_2(T,\Omega)$. This results in deviations from

our BQP and superconducting state optical scattering rates even in the

region where these have merged and are, in addition, close to the normal

state result.

Original language | English |
---|---|

Pages (from-to) | 144516 |

Number of pages | 9 |

Journal | Physical Review B |

Volume | 95 |

DOIs | |

Publication status | Published - 2017 |

## Keywords

- Superconductivity

## ASJC Scopus subject areas

- Condensed Matter Physics

## Fields of Expertise

- Sonstiges

## Treatment code (Nähere Zuordnung)

- Basic - Fundamental (Grundlagenforschung)