Design of a High Numerical Aperture Vacuum Chamber for Optical Lattice Experiments*

In our previous experiments, optical lattices have been used to study the behavior of ultra-cold fermions in a 3D realization of the Hubbard model¹. The necessity of small lattice beams, however, leads to inhomogeneous confinement. We previously used blue-detuned (anti-trapping) beams to flatten the confining potential² in order to detect antiferromagnetic (AFM) spinordering¹. Finer details in the confinement potential can be realized by implementing a vacuum chamber with a large numerical aperture (NA) for the compensation beams. As a result, the AFM phase region can be enlarged through improved flattening of the potential and sharpening of the walls separating the various phases. More specifically, entropy redistribution may be achieved by imposing entropy storing reservoirs surrounding the main region of interest.

¹R. A. Hart et al. Nature. 519, 211-214 (2015)

²C. J. M. Mathy et al. Phys. Rev. A. 86, 023606 (2012)