Aleksei V. Taichenachev

High-contrast dark resonances on the D1 line of alkali metals in the field of counterpropagating waves

A new method providing a significant increase in the amplitude and contrast of dark resonances is proposed. The method is based on the use of the σ+−σ− configuration of polarized counterpropagating waves, D1-line excitation in alkali metal atoms, and small-sized cells. Qualitative considerations of the scheme are confirmed by the results of numerical calculations. A variant of a standing wave with homogeneous circular polarization is also discussed.

Experimental investigation of the dark pseudoresonance on the D1 line of the 87Rb atom excited by a linearly polarized field

The measurements of the metrological characteristics (amplitude, width, and shift in the magnetic field) of the dark pseudoresonance, which was proposed by Kazakov et al. [quant-ph/0506167] as the reference resonance for an atomic frequency standard, are reported. It has been shown that the characteristics of the pseudoresonance are worse than those of the unsplit electromagnetically induced transparency resonance for the excitation scheme with the lin‖lin polarization on the D1 line of the 87Rb atom.

Transient processes under dynamic excitation of a coherent population trapping resonance

It is shown for the first time that under dynamic excitation of a coherent population trapping resonance in Rb vapours at different bichromatic pump modulation frequencies from a few tens of hertz and higher, the resonance is dramatically deformed as a result of emerging intensity oscillations of radiation transmitted through an Rb vapour cell. A significant change in the shape of the resonance under its dynamic excitation is confirmed experimentally and theoretically. A possible impact of the identified changes in the shape of the coherent population trapping resonance on the stability of an atomic clock is qualitatively discussed.

Possibility of the use of the magnetic field for creating a quantum filter on the D187Rb line

The possibility of the use of the F = 2↔F = 1 transition of the D1 absorption line of the 87Rb atom for creating of a single-photon quantum filter based on coherent population trapping (CPT) has been analyzed. It has been shown that the external magnetic field is necessary for ensuring the creation of the quantum filter on boson isotopes of alkali atoms. The field strength should be enough for the manifestation of the splitting of the Zeeman CPT resonances that is much larger than their spectral widths. The splittings of the CPT resonances, which characterize the nonlinearity of the Zeeman effect, have been measured for the 87Rb atom and the possibility of the use of this system for the quantum filter is concluded.

High contrast dark resonances in a cold-atom clock probed with counterpropagating circularly polarized beams

A cold-atom coherent population trapping clock based on σ+−σ− interrogation realized by counter-propagating optical fields of opposite circular polarization is presented. The simultaneous use of σ+ and σ− polarizations prevents atoms from being trapped in the end magnetic sublevels, significantly enhancing the contrast over interrogation with a single circular polarization. Because the system is based on cold atoms and there is very little relaxation, nearly complete dark states are created, and coherent population trapping resonances with maximum contrast are observed. A frequency stability of 1.3×10−11/√τ is achieved, which averages down to 2×10−13 after a 40u2009000u2009s integration period.