Hannover 2013 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 23: Quantum gases: Interaction effects II

Q 23.3: Talk

Tuesday, March 19, 2013, 11:45–12:00, E 001

Intrinsic optical bistability in a cooperative Rydberg ensemble — •Christopher Carr, Ralf Ritter, Kevin Weatherill, and Charles Adams — Joint Quantum Centre (JQC), Durham University, Durham, England

We demonstrate a non-equilibrium phase transition in a cooperative Rydberg ensemble. A thermal Rydberg ensemble provides an ideal environment for studying cooperative effects which dominate when the number of atoms per cubic wavelength is large [1,2]. We perform a three-photon excitation scheme to Rydberg states in Caesium which allows us to obtain high Rydberg densities [3] and large transition wavelengths to nearby states.

The first-order non-equilibrium phase transition in the atom-light interaction occurs due to competition between a single-body response and a cooperative many-body response. Long-range correlations between Rydberg atoms arise due to virtual photon exchange in the dipole-dipole interaction. In the frequency domain, we observe a cooperative mean-field shift resulting in intrinsic optical bistability [4]. In the time domain, we observe a superradiant Rydberg cascade [5] due to cooperative emission.

[1] J. Keaveney et al., Phys. Rev. Lett. 108 173601 (2012)

[2] J. Pritchard et al., Phys. Rev. Lett. 105 193603 (2010)

[3] C. Carr et al., Opt. Lett. 37 3858 (2012)

[4] M. Hehlen et al., Phys. Rev. Lett. 73 1103 (1994)

[5] F. Gounand et al., J. Phys. B 12 547 (1979)