Atomic coherence

About: Atomic coherence is a research topic. Over the lifetime, 877 publications have been published within this topic receiving 29395 citations.

Quantum-beat based dissipation for spin squeezing and light entanglement.

Abstract: We show an engineered dissipation for the spin squeezing and the light entanglement in a quantum beat system, in which two bright fields interact with an ensemble of three-level atoms in V configuration. The dissipation is based on the atom-field nonlinear interaction that is controlled by the atomic coherence between the excited states off two-photon resonance. Physical analysis and numerical verification are presented for the symmetrical parameters by using the dressed atomic states. It is shown that for particular parameters, the engineered dissipation induces almost perfect two-mode squeezing and entanglement both for the bright fields and for the dressed spins. The excited-state spin has squeezing of near 40% below the standard quantum limit although there remains the spontaneous emission from the involved excited states.

Magnetometer based on atomic coherence and possible application to the search for P and T violating permanent electric dipole moments of atoms

Abstract: A new approach to the experimental search for P and T violating permanent electric dipole moments (EDMs) in atoms is proposed. The high dispersion of a phase coherent atomic medium at a point of electromagnetically induced transparency is used to detect linear Stark-shifts associated with an atomic EDM in a highly sensitive interferometric measurement. Possible noise sources are analysed and estimates are given for the device sensitivity.

Light-matter entanglement via dark-state resonances

Abstract: We show that dark-state resonances can be a fundamental mechanism for the entanglement between light and matter. While two optical fields trap an ensemble of three-level {Lambda} atoms into the dark state, the coherence is created between the two metastable states, and the two fields undergo no absorption. The trapped atoms behave like a coherently coupled two-party reservoir and act on the two fields. As a result, Einstein-Podolsky-Rosen entanglement is obtainable between the atomic ensemble and one collective field under proper parameter conditions. Long-lived atomic coherence and no need of nonclassical input light are the advantages for quantum communications between light and matter based on the present mechanism.

Λ-type lasers and masers: Lasing without inversion and a vector model

Abstract: We show that the problem of a \ensuremath{\Lambda}-type (and also a V-type) three-level single-mode laser (maser) is isomorphic to that of a two-level single-mode laser (maser) under the conditions of energy-level degeneracy and equal decay rates. This correspondence reveals that lasing without population inversion can occur in the \ensuremath{\Lambda}-type system with or without an initial atomic coherence, and also gives immediately the master equation of the laser (maser) field. We analyze in detail the operational and noise properties of a \ensuremath{\Lambda}-type laser using a Fokker-Planck approach. We also present a vector model to visualize the population trapping and the absorption and emission processes in such a laser (maser) system.