Cooling ultracold bosons in optical lattices by spectral transform

TL;DR

This paper presents a theoretical method to measure and cool ultracold bosons in optical lattices by transforming their energy states into real-space sites, enabling non-destructive imaging and efficient cooling.

Contribution

It introduces a spectral transform technique that maps energy states to lattice sites, allowing in situ temperature measurement and cooling of ultracold bosons in optical lattices.

Findings

Spectral transform effectively maps energy states to lattice sites.

Method enables non-destructive energy distribution measurement.

Numerical analysis shows robustness against interactions and errors.

Abstract

It is shown theoretically how to directly obtain the energy distribution of a weakly interacting gas of bosons confined in an optical lattice in the tight-binding limit. This is accomplished by adding a linear potential to a suitably prepared lattice, and allowing the gas to evolve under the influence of the total potential. After a prescribed time, a spectral transform is effected where each (highly non-local) energy state is transformed into a distinct site of the lattice, thus allowing the energy distribution to be (non-destructively) imaged in real space. Evolving for twice the time returns the atoms to their initial state. The results suggest efficient methods to both measure the temperature in situ, as well as to cool atoms within the lattice: after applying the spectral transform one simply needs to remove atoms from all but a few lattice sites. Using exact numerical calculations, the effects of interactions and errors in the application of the lattice are examined.