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arXiv:2111.15188 · Physical Review A

Site-resolved imaging of a bosonic Mott insulator of Li7 atoms

Kiryang Kwon, Kyungtae Kim, Junhyeok Hur, SeungJung Huh, Jae-yoon Choi

Published Mar 31, 2022• 17 citations
arXivHTMLPDF

Abstract

We demonstrate single-site and single-atom-resolved fluorescence imaging of a bosonic Mott insulator of $^{7}\mathrm{Li}$ atoms in an optical lattice. The fluorescence images are obtained by implementing Raman sideband cooling on a deep two-dimensional square lattice, where we collect scattered photons with a high numerical aperture objective lens. The square lattice is created by a folded retroreflected beam configuration that can reach a 2.5 mK lattice depth from a single laser source. The lattice beam is elliptically focused to have a large area with deep potential. On average, 4000 photons are collected per atom during 1 s of Raman sideband cooling and the imaging fidelity is over $95%$ in the central $80\ifmmode\times\else\texttimes\fi{}80$ lattice sites. As a first step to study correlated quantum phases, we present the site-resolved imaging of a Mott insulator. By tuning the magnetic field near the Feshbach resonance, the scattering length can be increased to $680{a}_{B}$ and we are able to produce a large-sized unity filling Mott insulator with 2000 atoms at low temperature. Our work provides a stepping stone to further in-depth investigations of intriguing quantum many-body phases in optical lattices.

DOI
10.1103/physreva.105.033323

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Quantum gas microscopes have expanded the capabilities of quantum simulation of Hubbard models by enabling the study of spatial spin and density correlations in square lattices.However, quantum gas microscopes have not been realized for fermionic atoms in frustrated geometries.Here, we demonstrate the single-atom resolved imaging of ultracold fermionic 6 Li atoms in a triangular optical lattice with a lattice constant of 1003 nm.The optical lattice is formed by a recycled narrow-linewidth, high-power laser combined with a light sheet to allow for Raman sideband cooling on the D 1 line.We optically resolve single atoms on individual lattice sites using a high-resolution objective to collect scattered photons while cooling them close to the two-dimensional ground vibrational level in each lattice site.By reconstructing the lattice occupation, we measure an imaging fidelity of approximately 98%.Our triangular lattice microscope platform for fermions clears the path for studying spin-spin correlations, entanglement, and dynamics of geometrically frustrated Hubbard systems which are expected to exhibit exotic emergent phenomena including spin liquids and kinetic frustration.
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