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TT: Fachverband Tiefe Temperaturen

TT 41: Matter at Low Temperature: Quantum Liquids, Bose-Einstein-Condensates, Ultra-cold Atoms

TT 41.12: Vortrag

Donnerstag, 26. März 2009, 17:00–17:15, HSZ 105

Quantum critical behavior in strongly interacting Rydberg gases — •Hendrik Weimer¹, Robert Löw², Tilman Pfau², and Hans Peter Büchler¹ — ¹Institut für Theoretische Physik III, Universität Stuttgart — ²5. Physikalisches Institut, Universität Stuttgart

We analyze the van der Waals blockade and the quantum evolution of an atomic gas resonantly driven by a laser into a strongly interacting Rydberg state. The main mechanism behind the van der Waals blockade is that once a Rydberg atom is excited, the van der Waals interaction shifts the surrounding atoms out of resonance with the driving laser and therefore suppresses the excitation of additional Rydberg atoms. We show that the system is close to the critical point of a second order phase transition and can be described by a universal scaling function with a critical exponent. We present an effective dynamical theory for the scaling function that provides excellent agreement with a numerical solution of the full Schrödinger equation.

[1] H. Weimer, R. Löw, T. Pfau, H. P. Büchler, Phys. Rev. Lett. 101, 250601 (2008).