Tuesday, August 6, 2013

1308.0793 (Michel Bauer et al.)

Real time imaging of quantum and thermal fluctuations: the case of a
two-level system

Michel Bauer, Denis Bernard
A quantum system in contact with a heat bath undergoes quantum transitions between energy levels upon absorption or emission of energy quanta by the bath. These transitions remain virtual until the energy of the system is measured repeatedly, even continuously in time. Isolating the two indispensible mechanisms in competition, we describe in a synthetic way the main physical features of thermally activated quantum jumps. Using classical tools of stochastic analysis, we compute in the case of a Q-bit the complete statistics of jumps and transition times in the limit when the typical measurement time is small compared to the thermal relaxation time. The emerging picture is that quantum trajectories are similar to those of a classical particle in a noisy environment, subject to transitions a la Kramers in a multi well landscape, but with a large multiplicative noise.
View original: http://arxiv.org/abs/1308.0793

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