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arXiv · 1407.7446

Signatures of the $A^2$ term in ultrastrongly-coupled oscillators

Tommaso Tufarelli·K. R. McEnery·S. A. Maier·M. S. Kim
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Abstract

We study a bosonic matter excitation coupled to a single-mode cavity field via electric dipole. Counter-rotating and $A^2$ terms are included in the interaction model, ${\mathbf A}$ being the vector potential of the cavity field. In the ultrastrong coupling regime the vacuum of the bare modes is no longer the ground state of the Hamiltonian and contains a nonzero population of polaritons, the true normal modes of the system. If the parameters of the model satisfy the Thomas-Reiche-Kuhn sum rule, we find that the two polaritons are always equally populated. We show how this prediction could be tested in a quenching experiment, by rapidly switching on the coupling and analyzing the radiation emitted by the cavity. A refinement of the model based on a microscopic minimal coupling Hamiltonian is also provided, and its consequences on our results are characterized analytically.

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Tommaso Tufarelli, K. R. McEnery, S. A. Maier, M. S. Kim. 2015-07-01. Signatures of the $A^2$ term in ultrastrongly-coupled oscillators. https://doi.org/10.1103/physreva.91.063840

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