Green-function method in the theory of ultraslow electromagnetic waves in an ideal gas with Bose-Einstein condensates

Abstract

We propose a microscopic approach describing the interaction of an ideal gas of hydrogenlike atoms with a weak electromagnetic field. This approach is based on the Green-function formalism and an approximate formulation of the method of second quantization for quantum many-particle systems in the presence of bound states of particles. The dependencies of the propagation velocity and damping rate of electromagnetic pulses on the microscopic characteristics of the system are studied for a gas of hydrogenlike atoms. For a Bose-Einstein condensate of alkali-metal atoms we find the conditions when the electromagnetic waves of both the optical and microwave regions are slowed. In the framework of the proposed approach, the influence of an external homogeneous and static magnetic field on the slowing phenomenon is studied.

Bose-Einstein condensation of photons in a plasma

“…Although a particle equilibration based on a delicate pump-loss balance does not necessarily lead to thermal equilibrium, a subsequent work by the same authors has produced compelling arguments favoring the observation of a genuine, secondorder phase transition characterizing Bose-Einstein condensation of photons [16]. Another recent and appealing theoretical proposal, based on the concept of slow light [17,18], has been put forward by Boichenko and Slyusarenko [19], who considered the coexistence of photonic and atomic BECs. Moreover, a comprehensive theory of photon condensation in optical cavities in the presence of a medium has been developed by Kruchkov [20].…”

Propagation of relativistic charged particles in ultracold atomic gases with Bose-Einstein condensates

“…For a description of the electromagnetic properties of dilute gases in some cases, one may use the ideal gas approximation (see Ref. [6] for details). As it is easy to see, this model is also convenient for studying the effects that take place during the interaction of the charged particle with a BEC in vapors of * slusarenko@kipt.kharkov.ua alkali-metal atoms.…”

“…As it is easy to see, this model is also convenient for studying the effects that take place during the interaction of the charged particle with a BEC in vapors of * slusarenko@kipt.kharkov.ua alkali-metal atoms. For gases with comparably low densities of atoms, ν 10 14 cm −3 , the microscopic approach is developed [6]. In the framework of this model, it is shown that the dispersion characteristics of a gas can be described with good accuracy by analyzing the relation for its permittivity.…”

“…(15), but the dispersion characteristics of a gas in the case of optical pumping cannot be studied in an appropriate way in the framework of the present paper. Really, the influence of additional strong fields result in the repopulation of the quantum states and thus it is necessary to go beyond the limits of the linear response theory [6], which are used in this paper.…”

“…The extreme conditions for the temperatures can result in more vivid manifestation of the physical phenomena that are well studied for other systems. For example, one of these effects is the ultraslow light phenomenon in BECs [5,6]. Therefore, now Bose-Einstein condensates are considered by many physicists as unique systems from the standpoint of experimental observations and theoretical studies.…”