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### Event Number 3323

**Atomic Physics Seminar****Coherent control of strongly interacting Rydberg gases in thermal vapor cells****Time:**2:00 pm**Place:**5310 Chamberlin Hall**Speaker:**Prof. Tilman Pfau, University of Stuttgart**Abstract:**Rydberg atoms are of great interest due to their prospects in quantum information processing. Coherent control of the strong Rydberg-Rydberg interaction allows for the realization of quantum operations and devices such as quantum gates and single-photon sources. To date, impressive experimental progress has been limited to the ultracold domain [1]. Being able to exploit this interaction in a coherent manner in thermal vapor would eliminate the need for cooling and trapping of atoms and thus offer new prospects for applications in terms of integration and scalability.<br><br>

We present our progress on the coherent control and investigation of Rydberg atoms in small vapor cells. We show that we are able to drive Rabi oscillations on the nanosecond timescale to a Rydberg state by using a pulsed laser excitation and are therefore faster than the coherence time limitation given by the Doppler width [2].<br><br>

A systematic investigation of the dephasing of these oscillations for different atomic densities and Rydberg S-states (n = 22-40) reveals a clear signature for Rydberg-Rydberg interaction which is the basis for quantum devices based on the Rydberg blockade. Due to the high excitation bandwidth we are probing interaction level shifts up to a few GHz which correspond to very small interatomic distances (&lt; 1μm). Despite the complicated level structure for Rydberg molecular states at these distances we find that the scaling with principle quantum number is still consistent with van der Waals type interaction. The strength of the interaction exceeds the energy scale of thermal motion (i.e. the Doppler broadening) and therefore enables strong quantum correlations above room temperature [3].<br><br>

Furthermore we present our latest results on the combination of the pulsed Rydberg excitation with a four-wave-mixing scheme [4] and our progress towards the creation of non-classical light. <br><br>

[1] M. Saffman et al., RMP 82, 2313 (2010) and references therein <br><br>

[2] B. Huber et al., PRL 107, 243001 (2011) <br><br>

[3] T. Baluktsian et al., PRL 110, 123001 (2013)<br><br>

[4] M. Saffman and T. G. Walker, Phys. Rev. A 66, 065403 (2002), M. M. Müller, et al. Phys. Rev. A 87, 053412 (2013)<br><br>

**Host:**Saffman- Add this event to your calendar