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arXiv · 1905.07590

Symmetry-breaking in a condensate of light and its use as a quantum sensor

Robert Bennett·Yaroslav Gorbachev·Stefan Yoshi Buhmann
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Abstract

Bose-Einstein condensates (BECs) represent one of the very few manifestations of purely quantum effects on a macroscopic level. The vast majority of BECs achieved in the lab to date consist of bosonic atoms, which macroscopically populate the ground state once a threshold temperature has been reached. Recently, a new type of condensate was observed - the photon BEC, where light in a dye-filled cavity thermalises with dye molecules under the influence of an external driving laser, condensing to the lowest-energy mode. However, the precise relationship between the photon BEC and symmetry-breaking phenomena has not yet been investigated. Here we consider medium-induced symmetry breaking in a photon BEC and show that it can be used as a quantum sensor. The introduction of polarisable objects such as chiral molecules lifts the degeneracy between cavity modes of different polarisations. Even a tiny imbalance is imprinted on the condensate polarisation in a 'winner takes it all' effect. When used as a sensor for enantiomeric excess, the predicted sensitivity exceeds that of contemporary methods based on circular dichroism. Our results introduce a new symmetry-breaking mechanism that is independent of the external pump, and demonstrate that the photon BEC can be used for practical purposes.

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Robert Bennett, Yaroslav Gorbachev, Stefan Yoshi Buhmann. 2019-05-18. Symmetry-breaking in a condensate of light and its use as a quantum sensor. https://doi.org/10.1103/physrevapplied.13.044031

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