From power law intermittence to macroscopic coherent regime

摘要

We address the problem of establishing which is the proper form of quantum master equationgenerating a survival probability identical to that corresponding to the nonergodic sequence of "lighton" and "light off' fluorescence fluctuations in blinking quantum dots. We adopt a theoreticalperspective based on the assumption that the abrupt transitions from the light on to light off state arethe results of many collisions between system and environment, properly described by the Lindbladequation, and that between two consecutive collisions the system dynamics are frozen. Thisgenerates a quantum master equation belonging to the recently proposed class of generalizedLindblad equations, with a time convoluted structure, involving in the specific case of this paperboth the unitary and the nonunitary contribution of the Lindblad equation. This is the property thatunder the low-frequency condition makes the new class of generalized Lindblad equation generatesthe required survival probability. We make the conjecture that this equation corresponds to thecooperative dynamics of many units that, in isolation, are described by the ordinary Lindbladequation. When the time scale of the unitary term of the Lindblad equation is shorter than thedephasing time, the cooperation generates a surprisingly extended macroscopic coherence.