The preparation of a sample of ultra cold caesium atoms in an ${m}_{F}=0$ Zeeman sublevel of the $F=3$ ground state is demonstrated, using cooling in an optical lattice and adiabatic passage. 97% of the atoms finally detected in the experiment populate the ${m}_{F}=0$ sublevel at a temperature of $300\phantom{\rule{0.3em}{0ex}}\mathrm{nK}$ . Microwave spectroscopy is used to measure the adiabatic transfer directly and its dependence on various experimental parameters. A theoretical model is provided to estimate the upper limit for the efficiency of adiabatic transfer in a multilevel system with nonresonant excitation. The results constitute significant progress towards constructing a caesium fountain frequency standard operating in the nK temperature range.The preparation of a sample of ultra cold caesium atoms in an ${m}_{F}=0$ Zeeman sublevel of the $F=3$ ground state is demonstrated, using cooling in an optical lattice and adiabatic passage. 97% of the atoms finally detected in the experiment populate the ${m}_{F}=0$ sublevel at a temperature of $300\phantom{\rule{0.3em}{0ex}}\mathrm{nK}$. Microwave spectroscopy is used to measure the adiabatic transfer directly and its dependence on various experimental parameters. A theoretical model is provided to estimate the upper limit for the efficiency of adiabatic transfer in a multilevel system with nonresonant excitation. The results constitute significant progress towards constructing a caesium fountain frequency standard operating in the nK temperature range.

Physical Review AMay 27, 200510 citations

The preparation of a sample of ultra cold caesium atoms in an

{m}_{F}=0

Zeeman sublevel of the

F=3

ground state is demonstrated, using cooling in an optical lattice and adiabatic passage. 97% of the atoms finally detected in the experiment populate the

{m}_{F}=0

sublevel at a temperature of

300\phantom{\rule{0.3em}{0ex}}\mathrm{nK}

. Microwave spectroscopy is used to measure the adiabatic transfer directly and its dependence on various experimental parameters. A theoretical model is provided to estimate the upper limit for the efficiency of adiabatic transfer in a multilevel system with nonresonant excitation. The results constitute significant progress towards constructing a caesium fountain frequency standard operating in the nK temperature range.