Coherence and Raman Sideband Cooling of a Single Atom in an Optical Tweezer 论文

摘要

We investigate quantum control of a single atom in a tightly focused optical tweezer trap. We show that inevitable spatially varying polarization gives rise to significant internal-state decoherence but that this effect can be mitigated by an appropriately chosen magnetic bias field. This enables Raman sideband cooling of a single atom close to its three-dimensional ground state (vibrational quantum numbers ${\overline{n}}_{x}={\overline{n}}_{y}=0.01$, ${\overline{n}}_{z}=8$) even for a trap beam waist as small as $w=900\text{ }\text{ }\mathrm{nm}$. The small atomic wave packet with $\ensuremath{\delta}x=\ensuremath{\delta}y=24\text{ }\text{ }\mathrm{nm}$ and $\ensuremath{\delta}z=270\text{ }\text{ }\mathrm{nm}$ represents a promising starting point for future hybrid quantum systems where atoms are placed in close proximity to surfaces.