Volume 73, Number 2, January 2006
|Page(s)||164 - 170|
|Published online||07 December 2005|
Antiresonances as precursors of decoherence
International Center for Theoretical Physics - Strada Costiera 11, 34014 Trieste, Italy
2 Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba Ciudad Universitaria, 5000 Córdoba, Argentina
3 Centro de Física, Instituto Venezolano de Investigaciones Científicas Apartado 21827, Caracas 1020A, Venezuela
Accepted: 9 November 2005
We show that, in the 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-Büttiker picture. This sheds new light on how the microscopic mechanisms that produce phase fluctuations induce decoherence.
PACS: 03.65.Yz – Decoherence, open systems; quantum statistical methods / 73.50.Bk – General theory, scattering mechanisms / 73.40.Gk – Tunneling
© EDP Sciences, 2006
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