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arXiv:2603.22238

Dressed-state master equation for two strongly coupled two-level atoms with long-lived entanglement

Artemisa Villalobos-Ramirez, Juan Mauricio Torres

quant-phSubmitted Mar 23, 2026• Announced Mar 24, 2026• 0 citations• Revised Aug 5, 2026 (v2)
v1 · Mar 23, 2026v2 · Aug 5, 2026
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Abstract

We derive a dressed-state master equation in Lindblad form for two strongly coupled two-level atoms. The resulting decay dynamics are governed by Lindblad operators that couple different dressed states. We show that the eigenvalues and eigenvectors of the Liouvillian can be obtained in a compact form, since each off-diagonal element in the dressed-state basis constitutes an eigenvector. Depending on the interatomic distance and the atomic transition frequency, the decay exhibits two well-separated time scales. On short times, the system relaxes into a pair of states, one of which is a transient, maximally entangled state. On longer times, this intermediate entanglement irreversibly decays into a separable steady state. Our results demonstrate that the intrinsic decay mechanism can transiently generate maximal entanglement, an effect that is not captured without the dressed-state master-equation formalism.

Comments
10 pages, 4 figures

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We propose a scheme that is able to generate on demand a steady-state entanglement between two nondegenerate cavity modes. The scheme relies on the interaction of the cavity modes with driven two- or three-level atoms, which act as a coupler to build entanglement between the modes. We show that, in the limit of a strong driving, it is crucial for the generation of entanglement between the modes to imbalance populations of the dressed states of the driven atomic transition. In the case of a three-level VVV-type atom, we find that a stationary entanglement can be created on demand by tuning the Rabi frequency of the driving field to the difference between the atomic transition frequencies. The resulting degeneracy of the energy levels, together with the spontaneously generated coherence, generate a steady-state entanglement between the cavity modes. It is shown that the condition for the maximal entanglement coincides with the collapse of the atomic system into a pure trapping state. We also show that the creation of entanglement depends strongly on the mutual polarization of the transition atomic dipole moments.