The Budapest Quantum Optics Group

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Critical exponent of dissipative phase transitions in a sub-ohmic bath

Dávid Nagy

(MTA Wigner RCP SZFI)

Time: Tue Jan 13 13:00:00 2015
Location: Building 1, Room 123

We study the effect of a colored reservoir on the critical exponent of a quantum phase transition in a driven-damped open system. We consider the simplest critical model of two coupled oscillators. One interacts with the usual Markovian reservoir at high frequency, the other one is coupled to a colored reservoir with a sub-ohmic spectral density function. Even at zero temperature the system is driven to a steady state. It has been well established that with the Markovian bath the critical exponent in the steady state is 1 instead of 1/2 corresponding to the ground state. We explore how the critical exponent can be tuned between these values by the spectral properties of the colored reservoir.