Trapping of Single Atoms in an Off-Resonance Optical Dipole Trap

Jun He, Baodong Yang, Yongjie Cheng +2 more

In our experiment, a single cesium atom prepared in a large-magnetic-gradient magneto-optical trap (MOT) can be efficiently transferred into a 1064-nm far-off-resonance microscopic optical dipole trap (FORT). The efficient transfer of the single atom between the two traps is used to determine the trapping lifetime and the effective temperature of the single atom in FORT. The typical trapping lifetime has been improved from ∼ 6.9 s to ∼ 130 s by decreasing the background pressure from ∼ 1 × 10 −10 Torr to ∼ 2 × 10 −11 Torr and applying one-shot 10-ms laser cooling phase. We also theoretically investigate the dependence of trapping lifetimes of a single atom in a FORT on trap parameters based on the FORT beam’s intensity noise induced heating. Numerical simulations show that the heating depends on the FORT beam’s waist size and the trap depth. The trapping time can be predicted based on effective temperature measurement of a single atom in the FORT and the intensity noise spectra of the FORT beam. These experimental results are found to be in agreement with the predictions of the heating model.

Chung-Yu Shih, Michael J. Gibbons, Michael Chapman

Rudolf Grimm, Matthias Weidemüller, Yuri B. Ovchinnikov

Jun He, Wang Jing, Baodong Yang +2 more

Based on our work on single cesium atoms trapped in a large-magnetic-gradient vapour-cell magneto-optical trap (MOT), the signal-to-noise ratio (SNR) is remarkably improved. Also a far-off-resonance optical dipole trap (FORT) formed by a strongly-focused 1064 nm single frequency Nd:YVO 4 laser beam is introduced. One cesium atom is prepared in the MOT, and then it can transfer successfully between the MOT and the FORT which is overlapped with the MOT. Utilizing the effective transfer, the lifetime of single atoms trapped in the FORT is measured to be 6.9 ± 0.3 s. Thus we provide a system where the atomic qubit can be coherently manipulated.

X.L. Zhang, Alexander Gill, Michael J. Gibbons +4 more

Cheng Wang, Peng Xu, Xiaodong He +2 more

The preparation and manipulation of single neutral atoms in optical dipole traps have important applications in quantum simulation and information. For this purpose, a single neutral atom, trapped in a static optical dipole trap which is formed by a strongly focused red-detuned far-off-resonance laser, can be transferred to a movable optical dipole trap when the movable trap crosses the static trap and the transfer efficiency can reach about 94%, meanwhile this transferred atom could be located at given position in the focal plane. This experimental result has potential applications in realizing entanglement of two individual neutral atoms in an optical dipole trap array.