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This work deals with the cooling and trapping of single cesium (Cs) atoms in a large-magnetic-gradient magneto-optical
trap (MOT) and the confinement of single Cs atoms in a far-off-resonance optical dipole trap (FORT). The experiment
setup is based on two large-numerical-aperture lens assemblies which allow us to strongly focus a 1064-nm TEM00-mode
Gaussian laser beam to a 1/e2 radius of ~ 2.3 μm to form a microscopic FORT for isolating single atom with environment
and to efficiently collect the laser-induced-fluorescence photons emitted by single atoms for detecting and recognizing
single atom’s internal state. We have tried both of “bottom-up” and “top-down” loading schemes to confine single atoms
in the microscopic FORT. In the “bottom-up” scheme, we have successfully prepared single Cs atoms in the MOT and
transferred it into FORT with a probability of almost 100%. In the “top-down” scheme, we have achieved ~ 74% of
single atom loading probability in the FORT using light-assisted collisions induced by blue detuning laser and with
prepared many Cs atoms in the MOT. The relaxation time in hyperfine level of ground state of trapped single Cs atom is
measured to be ~5.4 s. To coherently manipulate atomic quantum bits (qubit) encoded in the clock states (mF = 0 states in
Fg = 3 and 4 hyperfine levels) of single Cs atom via the two-photon simulated Raman adiabatic passage (STIRAP), we
have prepared two phase-locked laser beams with a frequency difference of ~ 9.192 GHz by optically injecting an
852-nm master laser to lock the +1-order sideband of a 9-GHz current-modulated slave diode laser. The two
phase-locked laser beams are used to drive STIRAP process in the Λ-type three-level system consists of Cs |6S1/2 Fg = 4,
mF = 0> and |6S1/2 Fg = 3, mF = 0< long-lived clock states and Cs |6S1/2 Fe = 4, mF = +1 > excited state with the
single-photon detuning of ~ -20 GHz. Rabi flopping experiments are in progress.
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