Browsing by Author "Aman, J.A."

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    Photoassociative spectroscopy of a halo molecule in 86Sr
    (American Physical Society, 2018) Aman, J.A.; Hill, J.C.; Ding, R.; Hazzard, Kaden R.A.; Killian, T.C.; Kon, W.Y.
    We present two-photon photoassociation to the least-bound vibrational level of the X1Σ+g electronic ground state of the 86Sr2 dimer and measure a binding energy of Eb=−83.00(7)(20)kHz. Because of the very small binding energy, this is a halo state corresponding to the scattering resonance for two 86Sr atoms at low temperature. The measured binding energy, combined with universal theory for a very weakly bound state on a potential that asymptotes to a van der Waals form, is used to determine an s-wave scattering length a=810.6(3)(9)a0, which is consistent with, but substantially more accurate than, the previously determined a=798(12)a0 found from mass scaling and precision spectroscopy of other Sr isotopes. For the intermediate state, we use a bound level on the metastable 1S0−3P1 potential. Large sensitivity of the dimer binding energy to light near resonant with the bound-bound transition to the intermediate state suggests that 86Sr has great promise for manipulating atom interactions optically and probing naturally occurring Efimov states.
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    Resonant Rydberg Dressing of Alkaline-Earth Atoms via Electromagnetically Induced Transparency
    (American Physical Society, 2016) Gaul, C.; DeSalvo, B.J.; Aman, J.A.; Dunning, F.B.; Killian, T.C.; Pohl, T.
    We develop an approach to generate finite-range atomic interactions via optical Rydberg-state excitation and study the underlying excitation dynamics in theory and experiment. In contrast to previous work, the proposed scheme is based on resonant optical driving and the establishment of a dark state under conditions of electromagnetically induced transparency (EIT). Analyzing the driven dissipative dynamics of the atomic gas, we show that the interplay between coherent light coupling, radiative decay, and strong Rydberg-Rydberg atom interactions leads to the emergence of sizable effective interactions while providing remarkably long coherence times. The latter are studied experimentally in a cold gas of strontium atoms for which the proposed scheme is most efficient. Our measured atom loss is in agreement with the theoretical prediction based on binary effective interactions between the driven atoms.
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    Rydberg-blockade effects in Autler-Townes spectra of ultracold strontium
    (American Physical Society, 2016) DeSalvo, B.J.; Aman, J.A.; Gaul, C.; Pohl, T.; Yoshida, S.; Burgdörfer, J.; Hazzard, K.R.A.; Dunning, F.B.; Killian, T.C.; Rice Center for Quantum Materials
    We present a combined experimental and theoretical study of the effects of Rydberg interactions on Autler-Townes spectra of ultracold gases of atomic strontium. Realizing two-photon Rydberg excitation via a long-lived triplet state allows us to probe the regime where Rydberg state decay presents the dominant decoherence mechanism. The effects of Rydberg interactions are observed in shifts, asymmetries, and broadening of the measured atom-loss spectra. The experiment is analyzed within a one-body density-matrix approach, accounting for interaction-induced level shifts and dephasing through nonlinear terms that approximately incorporate correlations due to the Rydberg blockade. This description yields good agreement with our experimental observations for short excitation times. For longer excitation times, the loss spectrum is altered qualitatively, suggesting additional dephasing mechanisms beyond the standard blockade mechanism based on pure van der Waals interactions.
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    Trap losses induced by near-resonant Rydberg dressing of cold atomic gases
    (American Physical Society, 2016) Aman, J.A.; DeSalvo, B.J.; Dunning, F.B.; Killian, T.C.; Yoshida, S.; Burgdörfer, J.
    The near-resonant dressing of cold strontium gases and Bose-Einstein condensates contained in an optical dipole trap (ODT) with the 5s30s3S1 Rydberg state is investigated as a function of the effective two-photon Rabi frequency, detuning, and dressing time. The measurements demonstrate that a rapid decrease in the ground-state atom population in the ODT occurs even for weak dressing and when well detuned from resonance. This decrease is attributed to Rydberg atom excitation, which can lead to direct escape from the trap and to population of very long-lived 5s5p3P0,2 metastable states. The effects of interactions between Rydberg atoms, including those populated by blackbody radiation, are analyzed. The work has important implications when considering the use of Rydberg dressing to control the interactions between dressed ground-state atoms.
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    Ultra-long-range Rydberg molecules in a divalent atomic system
    (American Physical Society, 2015) DeSalvo, B.J.; Aman, J.A.; Dunning, F.B.; Killian, T.C.; Sadeghpour, H.R.; Yoshida, S.; Burgdörfer, J.
    We report the creation of ultra-long-range Sr2 molecules comprising one ground-state 5s2 1S0 atom and one atom in a 5sns 3S1 Rydberg state for n ranging from 29 to 36. Molecules are created in a trapped ultracold atomic gas using two-photon excitation near resonant with the 5s5p 3P1 intermediate state, and their formation is detected through ground-state atom loss from the trap. The observed molecular binding energies are reproduced with the aid of first-order perturbation theory that utilizes a Fermi pseudopotential with effective s-wave and p-wave scattering lengths to describe the interaction between an excited Rydberg electron and a ground-state Sr atom.