Browsing by Author "Kanungo, S.K."

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    Realizing topological edge states with Rydberg-atom synthetic dimensions
    (Springer Nature, 2022) Kanungo, S.K.; Whalen, J.D.; Lu, Y.; Yuan, M.; Dasgupta, S.; Dunning, F.B.; Hazzard, K.R.A.; Killian, T.C.; Rice Center for Quantum Materials
    A discrete degree of freedom can be engineered to match the Hamiltonian of particles moving in a real-space lattice potential. Such synthetic dimensions are powerful tools for quantum simulation because of the control they offer and the ability to create configurations difficult to access in real space. Here, in an ultracold 84Sr atom, we demonstrate a synthetic-dimension based on Rydberg levels coupled with millimeter waves. Tunneling amplitudes between synthetic lattice sites and on-site potentials are set by the millimeter-wave amplitudes and detunings respectively. Alternating weak and strong tunneling in a one-dimensional configuration realizes the single-particle Su-Schrieffer-Heeger (SSH) Hamiltonian, a paradigmatic model of topological matter. Band structure is probed through optical excitation from the ground state to Rydberg levels, revealing symmetry-protected topological edge states at zero energy. Edge-state energies are robust to perturbations of tunneling-rates that preserve chiral symmetry, but can be shifted by the introduction of on-site potentials.
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    Spectroscopy of $^{87}\mathrm{Sr}$ triplet Rydberg states
    (American Physical Society, 2018) Ding, R.; Whalen, J.D.; Kanungo, S.K.; Killian, T.C.; Dunning, F.B.
    A combined experimental and theoretical spectroscopic study of high-n, 30≲n≲100, triplet S and D Rydberg states in 87Sr is presented. 87Sr has a large nuclear spin I=9/2, and at high-n the hyperfine interaction becomes comparable to, or even larger than, the fine structure and singlet-triplet splittings, which poses a considerable challenge both for precision spectroscopy and for theory. For high-n S states, the hyperfine shifts are evaluated nonperturbatively, taking advantage of earlier spectroscopic data for the I=0 isotope 88Sr, which results in good agreement with the present measurements. For the D states, this procedure is reversed by first extracting from the present 87Sr measurements the energies of the 3D1,2,3 states to be expected for isotopes without hyperfine structure (88Sr), which allows the determination of corrected quantum defects in the high-n limit.