Gauge issues in the description of solids with strong light-matter coupling

MPSD Seminar

  • Date: Nov 22, 2019
  • Time: 11:30 AM - 01:00 PM (Local Time Germany)
  • Speaker: Martin Eckstein
  • Friedrich-Alexander-Universität, Erlangen-Nürnberg
  • Location: CFEL (Bldg. 99)
  • Room: Seminar Room IV, O1.111
  • Host: Simone Latini, Angel Rubio
  • Contact:
The rich physics of complex condensed matter systems is largely understood in terms of minimal tight-binding models, which describe interacting electron systems on a lattice with only few valence orbitals per site. To incorporate a strong light-matter coupling into such models, one can project the continuum theory on a given set of valence bands.

However, alternative formulations arise when the projection to is performed in different gauges. Here we first compare the dipolar and projected Coulomb gauge Hamiltonian for a one-dimensional solid, to describe sub-cycle light-driven electronic motion in the semiclassical limit and the polariton bands in the quantum limit. Second, we discuss an excitonic insulator in a cavity. We show that the correct treatment of the light-matter interaction is essential to capture the behavior of the collective modes and the effect of the cavity on the phase transition even on a qualitative level.

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