Sub-Doppler cooling of Λ atoms in the field of two standing waves with a spatial phase shift

Dmitry V. Kosachiov, Yu. Rozhdestvensky, Gerard Nienhuis

D. V. Kosachev, Yu. V. Rozhdestvenskiǐ

D. V. Kosachev, Yu. V. Rozhdestvenskiǐ

Dmitry V. Kosachiov, Yu. Rozhdestvensky, Gerard Nienhuis

We present a general theoretical description of laser cooling of three-level atoms in a Λ configuration in two standing waves. Detunings, intensity, and spatial phase difference of the two waves are arbitrary. We demonstrate that, for a zero spatial phase shift, sub-Doppler cooling requires equal detunings. The basic mechanism is then coherent population trapping. For different detunings sub-Doppler cooling occurs only when the spatial phases of the two standing waves are different. This effect can be traced back to a mechanism of the Sisyphus type. These schemes of sub-Doppler cooling require neither polarization gradients nor magnetic fields.

Dmitry V. Kosachiov, Yu. Rozhdestvensky, M. K. Olsen +2 more

We present an investigation of an alternative mechanism for sub-Doppler cooling of atoms, based on a coherent population transfer in three-level \ensuremath{\Lambda} systems. The mechanism considered is that of a \ensuremath{\Lambda} atom interacting with two standing light waves with a mutual spatial phase shift cphi\ensuremath{\ne}0. The spatial dependence of the level populations of the \ensuremath{\Lambda} atom for different values of cphi is presented. For cphi\ensuremath{\ne}0, this clearly demonstrates coherent population transfer in an atom with transverse motion along the space-shifted nodes and antinodes of the two standing waves. We show that this allows translational temperatures well below the Doppler limit ${\mathit{T}}_{\mathit{D}}$=${\mathrm{\ensuremath{\Elzxh}}}_{\ensuremath{\gamma}}$/${\mathit{k}}_{\mathit{B}}$ to be achieved.

Dmitry V. Kosachiov

The work investigates A-atoms cooling in the field of two standing light waves with spatial shift p. It is shown that for certain values of 9, the cold atoms temperature can be much lower the Doppler limit, while for other ç sub-Doppler cooling don't takes place.