Zooming in on quantum trajectories

Michel Bauer (1) , Denis Bernard (2) , Antoine Tilloy (2)

1 IPHT - Institut de Physique Théorique - UMR CNRS 3681
2 LPTENS - Laboratoire de Physique Théorique de l'ENS [École Normale Supérieure]

We propose to use the effect of measurements instead of their number to study the time evolution of quantum systems under monitoring. This time redefinition acts like a microscope which blows up the inner details of seemingly instantaneous transitions like quantum jumps. In the simple example of a continuously monitored qubit coupled to a heat bath, we show that this procedure provides well defined and simple evolution equations in an otherwise singular strong monitoring limit. We show that there exists anomalous observable localised on sharp transitions which can only be resolved with our new effective time. We apply our simplified description to study the competition between information extraction and dissipation in the evolution of the linear entropy. Finally, we show that the evolution of the new time as a function of the real time is closely related to a stable Levy process of index 1/2.

Keywords: continuous quantum measurements; levy flights; quantum jumps; local time; quantum trajectories

Domains: Physics [physics]; Quantum Physics [quant-ph]; Physics [physics]; Mathematical Physics [math-ph]

Michel Bauer, Denis Bernard, Antoine Tilloy. Zooming in on quantum trajectories. Journal of Physics A: Mathematical and Theoretical, 2016, 49, pp.10LT01. ⟨10.1088/1751-8113/49/10/10LT01⟩. ⟨cea-01626652⟩