Entangled atoms in a cavity with an electromagnetic field

Abstract

We consider a system consisting of two identical particles (‘atoms’), each approximated by a harmonic oscillator, which couples to an electromagnetic field, inside a perfectly reflecting spherical cavity. Differently from the scalar field ohmic case, which is usually considered in similar previous papers, such an electromagnetic environment is instead categorized as a supra-ohmic (or superohmic) one. Through the introduction of center-of-mass and relative-position coordinates and employing the formalism of dressed coordinates and states, we are able to study the time evolution of the entanglement of the atoms. This is done for both large and small cavities, in a nonperturbative fashion. For very large cavities, we find, as expected, an almost exponential decay in time, for both the concurrence and the negativity of the system, while for small ones, these quantities show an irregular oscillation of the entanglement of the atoms, but it does not cease to the exist (there is no sudden death).