Quantum escape processes for driven systems

DIPC Seminars

Speaker

Dr. Alvise Verso, Ulm University

When

2011/01/14
13:00

Place

Donostia International Physics Center (DIPC).Paseo Manuel de Lardizabal, 4 (nearby the Facultad de Quimica), Donostia

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Motivated by recent experimental progress in the readout of superconducting quantum bits via dynamical bifurcation, transitions between steady orbits in a driven anharmonic oscillator (the Duffing oscillator) are analyzed. First, in the weak coupling limit a system plus reservoir model is applied to consistently derive the master equation for the reduced density in the moving frame. The concept of an effective temperature is introduced to analyze to what extent a detailed balance relation exists. Furthermore, a diffusion equation in the semiclassical limit is derived to capture the intimate relation between finite tunneling/reflection and the bath induced quantum fluctuations. An analytical expression for the switching probability is obtained. It is shown that a reduction of the transition rate due to finite reflection at the phase-space barrier is overcompensated by an increase due to environmental quantum fluctuations that are specific for diffusion processes over dynamical barriers.