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Seminarium ISQI - dr Karol Gietka

Virtual squeezing in strongly coupled light-matter systems: converting vacuum Rabi splitting into exotic two-mode squeezing

Speaker: Dr. Karol Gietka (Warsaw University)

Date, Time: 21.03, 14:00 - 15:00

Vacuum Rabi splitting relies on symmetrical splitting of the common resonance frequency of atoms and the cavity in which the atoms reside. In this work, we argue that vacuum Rabi splitting is a manifestation of virtual light-matter two-mode squeezing. We establish a connection between squeezing parameters of virtual excitations and frequency shifts of the physical modes. Subsequently, we concentrate on light-matter systems exhibiting the self-ordering phase transition, which is equivalent to the superradiant phase transition in the Dicke model, and discuss why observation of virtual squeezing is so elusive. To this end, we use the mapping between transversely driven atoms in the cavity and two interacting harmonic oscillators, which we analyze in the framework of virtual and physical excitations. Finally, we suggest that such virtual squeezing of quantum fields might be used to explain other phenomena, in particular, in the context of strong light-matter interaction and quantum phase transitions.