# Stuttgart 2012 – wissenschaftliches Programm

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# Q: Fachverband Quantenoptik und Photonik

## Q 37: SYRA: Ultracold Rydberg Atoms and Molecules 3

### Q 37.5: Vortrag

### Donnerstag, 15. März 2012, 11:30–11:45, V7.03

**Scaling laws and correlations in finite Rydberg gases** — •Martin Gärttner^{1,2}, Thomas Gasenzer^{2}, and Jörg Evers^{1} — ^{1}Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg — ^{2}Institut für Theoretische Physik, Ruprecht-Karls-Universität Heidelberg, Philosophenweg 16, D-69120 Heidelberg

We study the coherent dynamics of a finite laser-driven cloud of ultra-cold Rydberg atoms by calculating the time evolution from the full many body Hamiltonian. Using the frozen gas approximation and treating the atoms as effective two level systems, we are mainly interested in the spatially resolved properties of the gas in its thermalized state. Even for resonant coupling to the Rydberg state, the pair correlation function shows a pronounced structure. It turns out that a simple estimation of the blockade radius predicts the position of the first maximum of the *g*^{(2)}-function quite well. However, we show that algebraic scaling laws as predicted in [1] are modified by finite size effects which serves as a test of the validity of the super atom picture. At positive detuning crystalline structures are observed even without using chirped laser pulses [2], which can be explained by resonant excitation processes and finite size effects.

[1] H. Weimer *et al.*, Phys. Rev. Lett. 101, 250601 (2008)

[2] T. Pohl *et al.*, Phys. Rev. Lett. 104, 043002 (2010)