Analytical populations of a multilevel atom in a weak linearly-polarized light

Geol Moon, Seo Ro Shin, Heung‐Ryoul Noh

E. A. Gazazyan, G. G. Grigoryan, A. Papoyan

Amplification of a weak circularly polarized light signal in a multilevel atomic medium excited by a strong linearly polarized resonant radiation is studied. A strong optical pumping may lead to the population inversion between magnetic sublevels of hyperfine components of the ground and excited states. Solution to the self-consistent system of density matrix equations and Maxwell equations for propagation of the weak signal allows analyzing optimum conditions of amplification.

Geol Moon, Myung-Sun Heo, Seo Ro Shin +2 more

We present an analytic calculation of the population of each magnetic sublevel of the $^{87}\mathrm{Rb}$ atom. Under the influence of a weak circularly polarized laser beam, the rate equations governing the internal dynamics of this atom were solved analytically and the results were compared with numerical calculations. As far as the condition of low intensity is satisfied, it is possible to obtain exact analytic populations regardless of the magnitude of energy spacings, transition lines, and laser polarization (circular or linear).

Li-Xin Xia, Guojian Yang

Yifu Zhu, Shijun Wang, Neil Mulchan

We report an experimental observation of coherent population trapping in multilevel dark states prepared in the ground hyperfine states of ${}^{87}\mathrm{Rb}$ atoms confined in a room-temperature vapor cell. The dark states are created by a linearly polarized coupling laser that is tuned to the ${}^{87}\mathrm{Rb}$ ${D}_{1}$ $F=2\ensuremath{\leftrightarrow}{F}^{\ensuremath{'}}=1$ or 2 transition and establishes \ensuremath{\Lambda}-type transition chains. The Doppler shift for the \ensuremath{\Lambda}-type transition chains is compensated by the left and right circularly polarized components of the coupling laser. The multilevel dark states that consist of three or two magnetic sublevels among the five degenerate magnetic sublevels in the $F=2$ ground hyperfine state are probed by a weak probe laser scanned across the same ${D}_{1}$ transition and their existence is manifested by a strong dependence of the probe excitation on the probe polarization. Our experiment demonstrates the importance of coherent population trapping in a laser coupled degenerate multilevel open atomic system, which may play an important role in diverse physical phenomena such as atom cooling and trapping, optical pumping, and multiple laser excitation and ionization of atoms and molecules.

Ya I Khanin, Olga A. Kocharovskaya