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arXiv · 2111.02931

Optomechanical Response of a Strongly Interacting Fermi Gas

Victor Helson·Timo Zwettler·Kevin Roux·Hideki Konishi·Shun Uchino·Jean-Philippe Brantut
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Abstract

We study a Fermi gas with strong, tunable interactions dispersively coupled to a high-finesse cavity. Upon probing the system along the cavity axis, we observe a strong optomechanical Kerr nonlinearity originating from the density response of the gas to the intracavity field and measure it as a function of interaction strength. We find that the zero-frequency density response function of the Fermi gas increases by a factor of two from the Bardeen-Cooper-Schrieffer to the Bose-Einstein condensate regime. The results are in quantitative agreement with a theory based on operator-product expansion, expressing the density response in terms of universal functions of the interactions, the contact and the internal energy of the gas. This provides an example of a driven-dissipative, strongly correlated system with a strong nonlinear response, opening up perspectives for the sensing of weak perturbations or inducing long-range interactions in Fermi gases.

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Victor Helson, Timo Zwettler, Kevin Roux, Hideki Konishi, Shun Uchino, Jean-Philippe Brantut. 2021-11-04. Optomechanical Response of a Strongly Interacting Fermi Gas. https://doi.org/10.1103/physrevresearch.4.033199

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