Quantum-gas microscopes have become an important tool in quantum simulation as they enable direct probing of local quantities by single-atom-resolved detection in optical lattices. Recent years have seen many fascinating results from the bosonic quantum-gas microscopes using 87Rb. However, no such device existed for fermionic species.The goal of this thesis work was to develop and build a quantum-gas microscope setup for fermionic potassium-40. Single-atom-resolved imaging of 40K has proven very challenging due to its smaller mass and smaller excited-state hyperfine splitting compared to 87Rb. In addition, the inverted excited state trapping potential required us to employ electromagnetically induced transparency (EIT) cooling instead of sub-Doppler molasses cooling.EIT cooling occurs when a coherent driving of a three-level system generates a spectrally narrow Fano-like resonance which can be set to favour red-sideband transitions over blue ones of the quantised vibrational levels in the optical lattice potential. During the cooling process, the fluorescence light is collected by a high-NA objective to image the atomic distribution in a two-dimentional square lattice potential.Due to the physical constraints of our apparatus, EIT cooling had to be combined with coupling between different motional axes via Raman transitions to achieve cooling of all degrees of freedom. Our imaging method allowed us to collect about 1,000 fluorescence photons per atom within a 1.5 s exposure time. From the analysis of two distinct subsequent fluorescence images, we found that less than 5% of the atoms hopped or were lost during 1s of EIT cooling. Such fidelity will allow fermionic quantum-gas microscopes to investigate fermionic quantum phases, spin-spin correlations, and out of-equilibrium dynamics of correlated fermionic many-body quantum systems.
|Date of Award||25 May 2018|
- University Of Strathclyde
|Sponsors||EPSRC (Engineering and Physical Sciences Research Council)|
|Supervisor||Stefan Kuhr (Supervisor) & Erling Riis (Supervisor)|