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arXiv · 2509.05156

Casimir-Lifshitz Theory for Cavity Modification of Ground-State Energy

Oleg V. Kotov·Johannes Feist·Francisco J. García-Vidal·Timur O. Shegai
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Abstract

A theory for ground-state modifications of matter embedded in a Fabry-Perot cavity and whose excitations are described as harmonic oscillators is presented. Based on Lifshitz's theory for vacuum energy and employing a Lorentz model for the material permittivity, a nonperturbative macroscopic QED model that accounts for the infinite number of cavity modes with a continuum of their wavevectors was built. Differences from the commonly used single-mode Hopfield Hamiltonian are revealed. The nonresonant role of polaritons in the ground-state energy shift is also demonstrated, showing that the cavity effect is mainly caused by static screening occurring at very low frequencies. The theory allows for a straightforward incorporation of losses and temperature effects.

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Oleg V. Kotov, Johannes Feist, Francisco J. García-Vidal, Timur O. Shegai. 2025-09-05. Casimir-Lifshitz Theory for Cavity Modification of Ground-State Energy. https://doi.org/10.1103/v79d-tty5

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