Extending the trapping lifetime of single atom in a microscopic far-off-resonance optical dipole trap

Abstract

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.

Influence of Laser Intensity Fluctuation on Single-Cesium Atom Trapping Lifetime in a 1064-nm Microscopic Optical Tweezer

“…The typical trapping lifetime here we achieved seems shorter than that of our previous work [19] because the background Cs density in the ultra-high vacuum (UHV) glass cell has increased a lot in this experiment. Now the trapping lifetime of single atom in the optical tweezer is mainly limited by the atomic collisions under the typical pressure of approximately 6 × 10 −7 Pa.…”

“…The typical time of the MOT is 5.81 ± 0.14 s, and the pressure in the cell is about 6 × 10 −7 Pa. The temperature of atoms in the MOT is ∼105 µ K under similar conditions [19].…”

“…Adjusting the spatial overlap and temporal overlap of the MOT and the optical tweezer can transfer the single atom between the traps efficiently. The loading rate of the MOT R L is sensitive to the axial gradient of the quadrupole magnetic field ( dB dZ ), and R L ∝( dB dZ ) [19,20]. The smaller the axial gradient of the quadrupole magnetic field, the higher the MOT loading rate and the more captured atoms.…”

Quantum state manipulation of single-Cesium-atom qubit in a micro-optical trap

“…The lifetime is mainly limited by the background vacuum pressure and by the parametric heating due to fluctuation of trap beams [22]. In principle by reducing the vacuum pressure to the level of 10 −11 torr, the atom lifetime could be extended to 100 seconds [23,24]. However, the singleatom-qubit dephasing time is on the sub-second level, the current trapping time has no impact on demonstrating the internal state manipulations.…”

Optical levitation of a microdroplet containing a single quantum dot

“…Far-offresonance optical dipole traps, together with optical cavities, provides a rich playground for studying the interaction between single atoms and single photons [4]. The longest trapping lifetime reported to date for a single atom is ∼ 100 s [5], which is sufficiently long to demonstrate coherent state manipulation in the strong coupling regime [3].…”