Adiabatic focusing of cold atoms in a blue-detuned laser standing wave

Sergey V. Prants

Markus Mützel, D. Haubrich, Dieter Meschede

Lev Khaykovich, N. Friedman, Roee Ozeri +1 more

Summary form only given. A tightly focused and rapidly rotating blue-detuned laser beam was used to trap rubidium atoms in the dark with long atomic coherence times. Adiabatic compression and laser cooling then yielded atomic densities well above 10/sup 13/ cm/sup -3/.

Jian Chen

The effect of the dipole force and its fluctuation on the motion of Li atoms in an intense, one-dimensional, near-resonant standing light wave has been investigated, both theoretically and experimentally. The duration of the interaction of the atoms with the standing wave was varied from several tens of spontaneous emission lifetimes to several hundred. For a standing wave frequency blue-detuned from resonance, diffusive heating can dominate the time-averaged dissipative dipole force so that there is no steady-state momentum distribution. However, for sufficiently large blue detunings the rate of diffusion is so slow that the resulting distribution approaches a quasi-steady state. For red detunings the diffusion is balanced with the force and a true steady-state is achieved. A Monte Carlo method based on the density matrix equations in the dressed-state representation is applied to simulate the atomic motion. The dynamics of atom channeling is studied. One of the important applications of this investigation is adiabatic laser cooling of atoms. Lithium atoms channeled in the nodes of an intense standing wave radiation field are cooled to near the recoil limit, a single photon's momentum $\\hbar{k}$, by adiabatically reducing the radiation intensity. The final momentum distribution has a narrow component with a root mean squared momentum of 2 $\\hbar{k}$ in one-dimension. The data are compared with the results obtained by the Monte Carlo method. This process may be useful for cooling and increasing the phase-space density of atoms confined in a magnetic trap.

Jean Dalibard, A. Heidmann, Ch Salomon +3 more

Mikio Kozuma, Ken-ichi Nakagawa, Wonho Jhe +1 more

We abruptly subject laser-cooled ${}^{87}\mathrm{Rb}$ atoms to the one-dimensional, blue-detuned, optical standing-wave potential generated by two crossed probe laser beams and detect the phase change of the probe beam due to cold-atom dynamics. Damped oscillations of the observed phase signal are attributed to a temporal change of the root-mean-square position of the cold atoms relative to the minima of the periodic optical potential. The damping rate is in good agreement with numerical results, which take into account the potential anharmonicity but neglect spontaneous emission. The agreement indicates that the decay is mainly caused by dephasing due to trap anharmonicity. For sufficient low initial temperature, our calculations show quantum revivals of the wave-packet oscillation.