In a recent review, a team from the Institute for Laser Physics, Hamburg Centre for Ultrafast Imaging (University of Hamburg) and the Wilczek Quantum Centre (Zheijang University of Technology) give an overview of experimental work on Bose-Einstein condensation in optical lattices. The image below is a visual representation of the complex argument of superpositions of different orbitals, showing different phases.
Optical lattices use interfering laser beams to create regions of high- and low-field, allowing particles to be trapped in wells and manipulated and examined. For a great summary of the state of the field and an in depth explanations of the processes involved with and uses of optical lattices, I definitely recommend taking a look at the review below.
Read more: Orbital optical lattices with bosons
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Front Image and article image: The complex argument Arg(ψ++iψ–), respectively, calculated for Vxy,0=7 Erec and θ=0.75π. The colors orange, magenta, blue, green correspond to phase values 1, i, -1, -i respectively., adapted from T Kock et al 2016 J. Phys. B: At. Mol. Opt. Phys. 49 042001