Radiation from a collection of absorbing resonant systems in the presence of boundaries of intense fields

A. I. Alekseev, Viktor Mikhaĭlovich Galit︠s︡kiĭ

I. R. Khairulin, Yevgeny V. Radeonychev, V. A. Antonov +1 more

Abstract The induced transparency of opaque medium for resonant electromagnetic radiation is a powerful tool for manipulating the field-matter interaction. Various techniques to make different physical systems transparent for radiation from microwaves to x-rays were implemented. Most of them are based on the modification of the quantum-optical properties of the medium under the action of an external coherent electromagnetic field. Recently, an observation of acoustically induced transparency (AIT) of the 57Fe absorber for resonant 14.4-keV photons from the radioactive 57Co source was reported. About 150-fold suppression of the resonant absorption of photons due to collective acoustic oscillations of the nuclei was demonstrated. In this paper, we extend the AIT phenomenon to a novel phase-locked regime, when the transmitted photons are synchronized with the absorber vibration. We show that the advantages of synchrotron Mössbauer sources such as the deterministic periodic emission of radiation and controlled spectral-temporal characteristics of the emitted photons along with high-intensity photon flux in a tightly focused beam, make it possible to efficiently implement this regime, paving the way for the development of the acoustically controlled interface between hard x-ray photons and nuclear ensembles.

V. M. Arutyunyan, Eghine G. Kanetsyan, V. O. Chaltykyan

Marta Reina, Michelangelo Domina, Alessandro Ferreri +4 more

We consider the cooperative spontaneous emission of a system of two identical atoms interacting with the electromagnetic field in the vacuum state and in the presence of an oscillating mirror. We assume that the two atoms, one in the ground state and the other in the excited state, are prepared in a correlated (symmetric or antisymmetric) Bell-type state. We also suppose that the perfectly reflecting plate oscillates adiabatically, with the field modes satisfying the boundary conditions at the mirror surface at any given instant, so that the time dependence of the interaction Hamiltonian is entirely enclosed in the instantaneous atom-wall distance. Using time-dependent perturbation theory, we investigate the spectrum of the radiation emitted by the two-atom system, showing how the oscillation of the boundary modifies the features of the emitted spectrum, which exhibits two lateral peaks not present in the case of a static boundary. We also evaluate the transition rate to the collective ground state of the two-atom system in both cases of the superradiant (symmetric) and subradiant (antisymmetric) state. We show that it is modulated in time and that the presence of the oscillating mirror can enhance or inhibit the decay rate compared to the case of atoms in vacuum space or near a static boundary. Our results thus suggest that a dynamical (i.e., time-modulated) environment can offer further possibilities to control and manipulate radiative processes of atoms or molecules nearby, such as the cooperative decay, and strongly indicate a similar possibility for other radiative processes, for example, the resonance interaction and the energy transfer between atoms or molecules.

S. N. Andreev, A. V. Mikhailov, Vladimir N Ochkin +2 more

The self-radiation of an extended absorbing medium under the action of a laser field with a fast-changing frequency is studied. The oscillations in the time-dependent intensity of the medium radiation are found. These oscillations are caused by the beatings between the vibrations of the oscillator at the fast-changing exciting and constant resonance frequencies. The time duration between local peaks of the oscillations is inversely proportional to the difference between the resonance frequency of the oscillator and the instantaneous laser frequency.

Yu. A. Vdovin, V. M. Ermachenko