Dynamical instability of a driven-dissipative electron-hole condensate in the BCS-BEC crossover region
Abstract
We present a stability analysis on a driven-dissipative electron-hole condensate in the BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover region. Extending the combined BCS-Leggett theory with the generalized random phase approximation to the nonequilibrium case by employing the Keldysh formalism, we show that the pumping and decay of carriers causes a depairing effect on excitons. This phenomenon gives rise to an attractive interaction between excitons in the BEC regime, as well as a supercurrent that anomalously flows antiparallel to ∇ θ (r ) [where θ (r ) is the phase of the condensate] in the BCS regime, both leading to dynamical instabilities of an exciton BEC. Our results suggest that a substantial region of the exciton-BEC phase in the phase diagram (in terms of the interaction strength and the decay rate) is unstable.
- Publication:
-
Physical Review B
- Pub Date:
- September 2017
- DOI:
- 10.1103/PhysRevB.96.125206
- arXiv:
- arXiv:1610.08622
- Bibcode:
- 2017PhRvB..96l5206H
- Keywords:
-
- Condensed Matter - Strongly Correlated Electrons;
- Condensed Matter - Mesoscale and Nanoscale Physics;
- Condensed Matter - Other Condensed Matter;
- Condensed Matter - Quantum Gases;
- Condensed Matter - Superconductivity
- E-Print:
- 20 pages, 14 figures