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Evolution of Atomic Entanglement for Different Cavity-Field Statistics in Single-Mode Two-Photon Process
摘要： We study the evolution of entanglement for a pair of two-level Rydberg atoms passing one after the other into an ideal cavity filled with a single mode radiation field. The atoms interact with the cavity field via two-photon transitions. The initial joint state of two atoms that enter the cavity one after the other is unentangled. Interactions intervened by the single mode cavity photon field brings out the final two-atom mixed entangled type state. We use the well known measure appropriate for the mixed states, i.e. the entanglement of formation to quantify the entanglement. We calculate the entanglement of formation of the joint two-atom state as a function of the Rabi angle, for the Fock state field, coherent field and thermal field respectively inside the cavity. The change in the magnitude of atomic entanglement with cavity photon number has been discussed.
关键词： cavity quantum electrodynamics,two-photon transitions,entanglement of formation,entanglement,Rydberg atoms
更新于2025-09-10 09:29:36
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Cavity-QED interactions of several atoms
摘要： We study many-atom van der Waals forces arising from reversible atom–field interactions in cavity quantum electrodynamics by using a dressed-state approximation. In the most general case, a single-mode Dicke model for atoms, sharing an arbitrary number of excitations, placed in an imperfect cavity has been developed that leads to the vdW potential of such system. As special cases, we consider the single-excitation Dicke model and also the case of one atom in the presence of multi-photon excitation inside the cavity. In most of the paper, it is assumed that the atoms are distributed symmetrically with respect to the mode structure. This will decouple all asymmetric states, allowing us to ignore them throughout our calculations. The impact of asymmetric states is taken into account for a system wherein one atom, freely placed in a cavity, together with n ? 1 equally-coupled atoms is interacting with the cavity field. By assuming broadened Lorentzian modes instead of sharp ones, the cavity imperfections have been added to the calculations. The position dependence of the effective Rabi frequency is studied for the example of a planar cavity.
关键词： cavity quantum electrodynamics,van der Waals forces,planar cavity,dressed-state approximation,Dicke model,Rabi frequency
更新于2025-09-04 15:30:14
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Conserving approximations in cavity quantum electrodynamics: Implications for density functional theory of electron-photon systems
摘要： By analyzing the many-body problem for nonrelativistic electrons strongly coupled to photon modes of a microcavity I derive the exact momentum/force balance equation for cavity quantum electrodynamics. Implications of this equation for the electron self-energy and the exchange-correlation potential of the quantum electrodynamic time-dependent density functional (QED-TDDFT) are discussed. In particular I generalize the concept of (cid:2) derivability to construct approximations which ensure the correct momentum balance. It is shown that a recently proposed optimized effective potential approximation for QED-TDDFT is conserving, and its possible improvements are discussed.
关键词： cavity quantum electrodynamics,density functional theory,conserving approximations,momentum balance,electron-photon systems
更新于2025-09-04 15:30:14