Detecting multi-atomic composite states in optical lattices

TL;DR

This paper introduces methods to detect quasi-molecular complexes in strongly interacting optical lattices, focusing on composite fermions in Bose-Fermi mixtures, using noise correlation techniques to identify their formation and properties.

Contribution

It presents novel detection techniques for composite fermions in optical lattices, extending noise correlation interferometry to measure higher order correlations.

Findings

Periodic correlations in shot noise indicate composite fermion formation.

Direct detection and momentum distribution measurement of complexes are feasible.

Detection methods are limited for complexes with more than three atoms.

Abstract

We propose and discuss methods for detecting quasi-molecular complexes which are expected to form in strongly interacting optical lattice systems. Particular emphasis is placed on the detection of composite fermions forming in Bose-Fermi mixtures. We argue that, as an indirect indication of the composite fermions and a generic consequence of strong interactions, periodic correlations must appear in the atom shot noise of bosonic absorption images, similar to the bosonic Mott insulator [S. F\"olling, et al., Nature {\bf 434}, 481 (2005)]. The composites can also be detected directly and their quasi-momentum distribution measured. This method -- an extension of the technique of noise correlation interferometry [E. Altman et al., Phys. Rev. A {\bf 79}, 013603 (2004)] -- relies on measuring higher order correlations between the bosonic and fermionic shot noise in the absorption images. However, it fails for complexes consisting of more than three atoms.