DeSalvo, B.J.Aman, J.A.Gaul, C.Pohl, T.Yoshida, S.Burgdörfer, J.Hazzard, K.R.A.Dunning, F.B.Killian, T.C.2017-05-042017-05-042016DeSalvo, B.J., Aman, J.A., Gaul, C., et al.. "Rydberg-blockade effects in Autler-Townes spectra of ultracold strontium." <i>Physical Review A,</i> 93, no. 2 (2016) American Physical Society: https://doi.org/10.1103/PhysRevA.93.022709.https://hdl.handle.net/1911/94168We 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.engArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.Journal articlehttps://doi.org/10.1103/PhysRevA.93.022709