Abstract
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 ~98%. Our new 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.
Highlights
Frustrated quantum systems pose a significant challenge to condensed matter theory due to their extensive ground state degeneracy [1,2] and can show fractional quasi-particle statistics as known from quantum Hall physics [3]
We start with 600 000 6Li atoms in a 1070 nm crossed optical dipole trap (CDT) loaded from a magneto-optical trap (MOT)
To increase loading efficiency of the CDT, we use a compressed MOT stage where the power for both the cooling light and the repump light is decreased to 0.01% and the detuning is changed from −30 to −5 MHz within 4 ms
Summary
Frustrated quantum systems pose a significant challenge to condensed matter theory due to their extensive ground state degeneracy [1,2] and can show fractional quasi-particle statistics as known from quantum Hall physics [3]. Fermi-Hubbard systems were first realized with ultracold atoms in square lattices [22,23]. For revealing intricate correlations on short length scales, this asks for a fermionic quantum gas microscope, where all ultracold atoms in the many-body system can be imaged simultaneously. Existing fermionic quantum gas microscopes were used to study Hubbard models on square lattices [16,30,31,32,33,34,35]. We demonstrate a realization of a site-resolved quantum gas microscope of ultracold fermionic atoms in a triangular lattice, thereby paving the way for a platform to study frustrated Hubbard physics in a lattice with spacing of 1003 nm and strong tunneling in the tight-binding limit. We conclude with an outlook on the study of Fermi-Hubbard physics and frustrated quantum physics in our setup
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