Heidelberg 2015 – scientific programme
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A: Fachverband Atomphysik
A 42: Ultracold Plasmas and Rydberg Systems III (with Q)
A 42.2: Talk
Friday, March 27, 2015, 11:15–11:30, P/H2
Mesoscopic Rydberg-blockaded ensembles in the superatom regime and beyond — Tobias M. Weber, Michael Höning, Thomas Niederprüm, Torsten Manthey, •Oliver Thomas, Vera Guarrera, Michael Fleischhauer, Giovanni Barontini, and Herwig Ott — TU Kaiserslautern, Kaiserslautern, Germany
In recent years great progress has been made in understanding the collective behaviour introduced by Rydberg excitations in ultra cold gases. Because of their strong van der Waals interaction it is not possible to excite two Rydberg atoms resonantly within a blockade volume defined by the interaction strength and the excitation bandwidth. In dense atomic clouds hundreds of ground state atoms can be found within this volume, forming a so-called superatom. These strongly correlated ensembles show an increased excitation probability, described by an effective two-level system. Here we report on the controlled creation and characterization of an isolated mesoscopic superatom by means of accurate density engineering and excitation to Rydberg p-states [1]. Its variable size allows us to investigate the transition from a strongly confined effective two-level to an extended many-body system. By monitoring continuous laser-induced ionization we are able to determine the g2(τ) correlation function and observe the expected anti bunching effect for resonant excitation, as well as bunching for off resonant coupling. The observed amplitudes and timescales can be described with an effective rate-equation model.
[1]: T. M. Weber et al, Creation, excitation and ionization of a mesoscopic superatom. arXiv:1407.3611