Universal pair-polaritons in a strongly interacting Fermi gas

TL;DR

This paper demonstrates the creation of universal pair-polaritons in a strongly interacting Fermi gas via cavity QED, enabling direct, universal mapping of pair correlations and potential for fast, minimally destructive measurements of many-body quantum states.

Contribution

It introduces the first experimental realization of pair-polaritons in a strongly interacting Fermi gas, showing their universal dependence on interatomic interactions and potential for quantum measurement and control.

Findings

Observation of well-resolved pair-polaritons hybridizing photons and atom pairs.

Demonstration of the universal dependence of the pair-polariton spectrum on interatomic interactions.

Magnification of many-body effects by two orders of magnitude in energy.

Abstract

Cavity quantum electrodynamics (QED) manipulates the coupling of light with matter, and allows for several emitters to couple coherently with one light mode. However, even in a many-body system, the light-matter coupling mechanism was so far restricted to one body processes. Leveraging cavity QED for the quantum simulation of complex, many-body systems has thus far relied on multi-photon processes, scaling down the light-matter interaction to the low energy and slow time scales of the many-body problem. Here we report on cavity QED experiments using molecular transitions in a strongly interacting Fermi gas, directly coupling cavity photons to pairs of atoms. The interplay of strong light-matter and strong inter-particle interactions leads to well resolved pair-polaritons, hybrid excitations coherently mixing photons, atom pairs and molecules. The dependence of the pair-polariton spectrum on interatomic interactions is universal, independent of the transition used, demonstrating a direct mapping between pair correlations in the ground state and the optical spectrum. This represents a magnification of many-body effects by two orders of magnitude in energy. In the dispersive regime, it enables fast, minimally destructive measurements of pair correlations, and opens the way towards their measurements at the quantum limit and their coherent manipulation using dynamical, quantized optical fields.