Excitations in Simple Atomic Ensembles

Ashat M. Basharov

The spontaneous emission from an atomic ensemble localized in a microcavity with the participation of microcavity photons and an external broadband quantized electromagnetic field at the Raman resonance of photons with an optically forbidden (two-photon) atomic transition has been studied. The average spontaneous decay intensity has been calculated for simple cases. It is shown that the dynamics of spontaneous emission from this atomic ensemble differs generally from the conventional superradiance (spontaneous emission of an atomic ensemble at a one-photon optically allowed transition from excited to the ground state. When the atomic ensemble is strongly excited, the delay times and the emission pulse shape differ significantly. The parameter ranges where the spontaneous emission from the atomic ensemble under consideration at a two-photon Raman transition can be described as conventional superradiance with renormalized parameters are found. In the case of single excitation the photon emission probability depends on the number of photons and atoms in the microcavity.

F. J. Kok

G. V. Gadiyak, D. A. Kirzhnits, Yu. E. Lozovik

Guowan Zhang, Chenglin Bian, Liang Chen +2 more

In spontaneous Raman scattering in an atomic ensemble, a collective atomic spin wave is created in correlation with the Stokes field. When the Stokes photons from two or more such atomic ensembles are made indistinguishable, a 'which-way' collective atomic spin excitation is generated among the independent atomic ensembles. We demonstrate this phenomenon experimentally by reading out the atomic spin excitations and observing interference between the read-out beams. When a single-photon projective measurement is made on the indistinguishable Stokes photons, this simple scheme can be used to entangle independent atomic ensembles. Compared to other currently used methods, this scheme can be easily scaled up and has greater efficiency.

G. V. Gadiyak, D. A. Kirzhnits, Yu. E. Lozovik

Ashat M. Basharov

The paper states a simple and analytically solvable model for the generation of low-frequency emission via a localized excited ensemble of identical two-level quantum particles with a permanent dipole moment in conditions of collective spontaneous emission of the atomic ensemble.