Non-BCS-Type Enhancement of Superconductivity from Long-Range Photon Fluctuations

TKM Institutsseminar


Ahana Chakraborty


12/04/2021 12:00




Max Planck Institute for Physics of Complex Systems


Alexander Mirlin


Recently, the possibility of inducing superconductivity for electrons in two dimensional
materials has been proposed via cavity-mediated pairing [1]. In this talk, I will discuss why photons
are more interesting as a mediator of the pairing with respect to the phonons of the standard BCS
paradigm. Firstly, the photon-mediated electron-electron interactions are long range. This induces a
novel, non-BCS-type of pairing [2] mediated by on-shell, non-adiabatic photon fluctuations which
are not sensitive to the electron occupation but rather to the electron dispersion and lifetime at the
Fermi surface. For realistic parameters, also including photon loss, this results into a critical
temperature which can be more than one order of magnitude larger than the BCS prediction.
Secondly, this proposal opens up an even more exciting prospect to exploit state-of-the-art
engineering of the quantum states of light to control superconductivity [3]. In this talk, I will
describe our recent results in these directions obtained within a real-time field theoretic
[1] H. Gao, F. Schlawin, M. Buzzi, A. Cavalleri, and D. Jaksch, Phys. Rev. Lett. 125, 053602 (2020)
[2] Ahana Chakraborty and Francesco Piazza [arXiv: 2008.06513 (2020)]
[3] Ahana Chakraborty and Francesco Piazza [To appear in arXiv]