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TT: Fachverband Tiefe Temperaturen

TT 6: Superconductivity: Tunnelling & Josephson Junctions

TT 6.9: Vortrag

Montag, 11. März 2013, 11:45–12:00, H18

Quantum critical temperature of a modulated oscillator — Lingzhem Guo^1,2, Vittorio Peano³, •Michael Marthaler¹, Gerd Schön¹, and Mark Dykman³ — ¹Institut für Theoretische Festkörperphysik — ²Department of Physics, Beijing Normal University, Beijing 100875, China — ³Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA

We show that the rate of switching between the vibrational states of a modulated nonlinear oscillator is characterized by a quantum critical temperature T_c∝ℏ². The rate is independent of T for T<T_c. Above T_c there emerges a quantum crossover region where the slope of the logarithm of the distribution over the oscillator states displays a kink and the change of the switching rate with T is independent of the modulation. The results demonstrate the limitations of the conventional instanton theory of switching in systems lacking detailed balance.