Antiresonances as precursors of decoherence

LUIS E. F. FOA TORRES; HORACIO M. PASTAWSKI; ERNESTO MEDINA

EUROPHYSICS LETTERS

European Physical Society

Lugar: Londres; Año: 2006 vol. 73 p. 164 - 171

0295-5075

We show that, in presence of a complex spectrum, antiresonances act as a precursor for dephasing enabling the crossover to a fully decoherent transport even within a unitary Hamiltonian description. This general scenario is illustrated here by focusing on a quantum dot coupled to a chaotic cavity containing a finite, but large, number of states using a Hamiltonian formulation. For weak coupling to a chaotic cavity with a sufficiently dense spectrum, the ensuing complex structure of resonances and antiresonances leads to phase randomization under coarse graining in energy. Such phase instabilities and coarse graining are the ingredients for a mechanism producing decoherence and thus irreversibility. For the present simple model one finds a conductance that coincides with the one obtained by adding a ficticious voltage probe within the Landauer-Buettiker picture. This sheds new light on how the microscopic mechanisms that produce phase fluctuations induce decoherence. Europhysics Letters 73, 164 (2006). Seleccionado como dentro de los trabajos distinguidos del año 2006 para su distribución gratuita.