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 n̄x=n̄y=0.01, n̄z=8) even for a trap beam waist as small as w=900 nm. The small atomic wave packet with δx=δy=24 nm and δz=270 nm represents a promising starting point for future hybrid quantum systems where atoms are placed in close proximity to surfaces.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)