Power and polarization dependences of ultra-narrow electromagnetically induced absorption (EIA) spectra of
85Rb atoms in degenerate two-level system
Abstract We present theoretical and experimental studies of electromagnetically induced absorption (EIA) for the transition of 85 Rb-D2 line. From the results calculated by solving time-dependent density-matrix equations including the optical and Zeeman coherences connected via three-photon interactions, the EIA signals have ultra-narrow feature in low powers of coupling beam in both same- and orthogonal-polarization configurations for both stationary and thermal atoms. However, the ultra-narrow EIA signals from high powers of coupling laser beam still remained in the ultra-narrow state only in the same-polarization configuration for thermal atoms. The calculated results match well with experimental results except ultra-narrow EIA region considering linewidths of two separate coupling and probe lasers.
Effects of neighboring transitions through Doppler broadening on electromagnetically induced absorption (EIA) and electromagnetically induced transparency (EIT) of the degenerate two-level system at the F g =2→ F e =1,2, and 3 transitions of the 87 Rb D2 line have been investigated. Two different polarization configurations, such as linear parallel and linear perpendicular polarizations of coupling and probe lasers, have been studied. We study the significant variation of EIT and EIA due to the effect of the neighboring transitions via artificial variation of the hyperfine spacings of the 5 P 3/2 state. We have a new observation such as EIT instead of EIA due to the neighboring effect, even in the case of closed systems such as F g =2→ F e =3 of 87 Rb for the linear parallel configuration, for the first time to our best knowledge. The observed spectra match well with theoretically calculated spectra. EIAs for the open F g =2→ F e =1 and 2 transitions at the linear perpendicular polarization are observed due to neighboring effects. This system may be applied to optical switching systems for future quantum processing application.
Velocity selective optical pumping effects in electromagnetically induced absorption for
85Rb atoms: polarization dependences
We predict the occurrence of electromagnetically induced absorption (EIA) in cycling degenerate two-level transitions where
Fe=Fg+1 and
Fg>0, interacting with pump and probe lasers with the same polarization. The EIA is due to transfer of population (TOP) between the Zeeman levels of the ground hyperfine state, rather than transfer of coherence (TOC) which occurs for perpendicularly polarized lasers. We model EIA-TOP using a double two-level system (TLS) which we compare with the four-level
N system, which models EIA-TOC. When the pump intensity is low, both models give an EIA peak at line center. The effect of introducing phase-changing collisions is studied, in the presence and absence of Doppler broadening, for both the double TLS and
N systems. In the presence of phase-changing collisions, the central EIA peaks are narrowed in both models and persist to higher pump Rabi frequencies than in the absence of collisions. In the double TLS, in the presence of Doppler broadening, the central EIA-TOP peak becomes narrower and does not develop a dip in its center, in contrast to the
N system. The central dip that appears in the Doppler-broadened EIA-TOC spectrum can be wiped out by adding phase-changing collisions. We demonstrate that EIA-TOP can be obtained for realistic atomic transitions interacting with lasers that have the same polarization.