Exciton-polariton-BEC-excitation-mediated superconductivity

New on the arxiv:

Exciton-polariton mediated superconductivity
Authors: Fabrice P. Laussy, Alexey Kavokin, Ivan Shelykh
http://arxiv.org/abs/0907.2374

Abstract: We revisit the exciton mechanism of superconductivity in the framework of microcavity physics, replacing virtual excitons as a binding agent of Cooper pairs by excitations of a real exciton-polariton Bose-Einstein condensate. We consider a model microcavity where quantum wells with a two dimensional electron gas sandwich an undoped quantum well, where an exciton-polariton condensate is formed. We show that the critical temperature for superconductivity increases with the condensate population--opening a new route towards high temperature superconductivity.

---

The usual binding mechanism for a Cooper pair is some kind of attractive electron-boson-electron interaction. In the BCS theory the bosons are taken to be phonons, but in principle they could be anything. In particular, they could be excitations of a Bose condensate. There was some old work on this by Bardeen, Baym, and Pines when they were trying to make Cooper pairs of helium-3 through interactions mediated by helium-4:

Effective Interaction of He3 Atoms in Dilute Solutions of He3 in He4 at Low Temperatures
J. Bardeen, G. Baym, and D. Pines
Phys. Rev. 156, 207 - 221 (1967)

The new work suggests using exciton-polaritons, which are electron-hole pairs hybridized with laser photons, to serve a similar purpose. The basic appeal of exciton-polariton BECs is that they have a high transition temperature compared with other BECs so in principle an exciton polariton BEC could stabilize a relatively high-temperature superconductor via the electron--exciton-BEC-excitation--electron interaction.