Over the course of the project, we have designed, assembled and operated the world first and only experimental setup combining strongly correlated Fermi gases with cavity quantum electrodynamics.
We have systematically explored the different regime of operation of this new type of quantum system: first, in the regime where the cavity photons are interacting resonantly with the atoms of the Fermi gas, we have observed the expected normal mode structure, and its scaling with the experimental parameters.
Throughout this exploration we encountered several unexpected resonances, which we traced back to the coupling of Fermion pairs with photons of the cavity. This new type of light-matter interaction, never observed before, led to the discovery of pair-polaritons, a new type of coherent quasiparticle. In turn, these new excitations could be leveraged to retrieve information about quantum correlations in a weakly destructive way. This finding had a high impact on the community, and exemplifies the opportunities open by the combination of two types of existing technologies (Fermi gases and cavity quantum electrodynamics).
We then turned to the exploration of the dispersive regime, were the atoms interact with cavity photons through their index of refraction. We first demonstrated the use of this regime for repeated, weakly destructive measurement, an enabling technology for the investigation of quantum dynamics, which originally motivated the design of the setup. There, we could also observe the hallmark of this type of coupling, namely strong optomechanical non-linearities. Again, the unique features of the combined Fermi-gas cavity system allowed for a new mapping between the correlations of the quantum gas and the cavity photons, which we could use to measure response functions in regimes not accessible by any other mean.
The last months of the project revealed yet another opportunity, namely the use of cavity photons to induce new phases of matter in the gas. We think that this promises transformative changes in the quantum simulation of strongly correlated matter by enabling the exploration of fundamental mechanisms encountered in the most complex examples of quantum materials.
The results have been widely disseminated in the academic scientific literature and at international conferences.
