Berlin 2012 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 4: Quantum Dynamics, Decoherence, and Quantum Information

DY 4.10: Talk

Monday, March 26, 2012, 17:30–17:45, MA 001

Phase transitions and dark-state physics in two-color superradiance — •Mathias Hayn, Clive Emary, and Tobias Brandes — Institut für Theoretische Physik, Technische Universität Berlin, 10623 Berlin

We theoretically study an extension of the Dicke model, where the single-particle Hamiltonian has three energy levels in Lambda configuration (i.e., the excited state is coupled to two nondegenerate ground states via two independent quantized light fields). The corresponding many-body Hamiltonian can be diagonalized in the thermodynamic limit with the help of a generalized Holstein-Primakoff transformation. Analyzing the ground-state energy and the excitation energies, we identify one normal and two superradiant phases, separated by phase transitions of both first and second oder. A phase with both superradiant states coexisting is not stable. In addition, in the limit of two degenerate ground states a dark state emerges, which seems to be analogous to the dark state appearing in the well-known stimulated Raman adiabatic passage scheme.

[1] M. Hayn, C. Emary, and T. Brandes, Phys. Rev. A 84, 053856 (2011)