Q-MAC meetings in 2020/2021:

The Final International Symposium has been postponed until further notice.

Q-MAC regular meeting 2020 has been cancelled. 

Read more

Q-MAC Extension on the grounds of excellence

Q-MAC Project has been successfully extended for 1 year

Read more

Publication Detail / Abstract

M. Kiffner, J. Coulthard, F. Schlawin, A. Ardavan, D. Jaksch

Mott polaritons in cavity-coupled quantum materials

published on New Journal of Physics on July 31, 2019
> Full text via publisher
We show that strong electron–electron interactions in quantum materials can give rise to electronic transitions that couple strongly to cavity fields, and collective enhancement of these interactions can result in ultrastrong effective coupling strengths. As a paradigmatic example we consider a Fermi–Hubbard model coupled to a single-mode cavity and find that resonant electron-cavity interactions result in the formation of a quasi-continuum of polariton branches. The vacuum Rabi splitting of the two outermost branches is collectively enhanced and scales with ${g}_{\mathrm{eff}}\propto \sqrt{2L}$, where L is the number of electronic sites, and the maximal achievable value for geff is determined by the volume of the unit cell of the crystal. We find that geff for existing quantum materials can by far exceed the width of the first excited Hubbard band. This effect can be experimentally observed via measurements of the optical conductivity and does not require ultrastrong coupling on the single-electron level. Quantum correlations in the electronic ground state as well as the microscopic nature of the light–matter interaction enhance the collective light–matter interaction compared to an ensemble of independent two-level atoms interacting with a cavity mode.
< Back