Direct observation of number squeezing in an optical lattice

TL;DR

This study directly observes number squeezing in an optical lattice with site-resolved imaging, revealing sub-Poissonian atom number fluctuations and non-ground state dynamics, which are crucial for quantum computing applications.

Contribution

The paper provides the first in-situ, high-resolution observation of atom number fluctuations and non-equilibrium states in an optical lattice, advancing understanding of quantum state preparation.

Findings

Observation of sub-Poissonian atom number distribution

Identification of density-dependent losses affecting the lattice

Lattice not in the ground state despite momentum distribution

Abstract

We present an in-situ study of an optical lattice with tunneling and single lattice site resolution. This system provides an important step for realizing a quantum computer. The real-space images show the fluctuations of the atom number in each site. The sub-Poissonian distribution results from the approach to the Mott insulator state, combined with the dynamics of density-dependent losses, which result from the high densities of optical lattice experiments. These losses are clear from the shape of the lattice profile. Furthermore, we find that the lattice is not in the ground state despite the momentum distribution which shows the reciprocal lattice. These effects may well be relevant for other optical lattice experiments, past and future. The lattice beams are derived from a microlens array, resulting in lattice beams which are perfectly stable relative to one another.