Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 103: Transport: Poster Session

TT 103.4: Poster

Donnerstag, 19. März 2015, 15:00–18:00, Poster B

Monitoring quantum transport: Backaction and measurement correlations — •Robert Hussein, Jorge Gómez-García, and Sigmund Kohler — Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid, Spain

We investigate a tunnel contact that is capacitively coupled to a double quantum dot and employed as charge monitor for the latter. We consider both the quantum regime and the classical limit characterized by the absence of quantum coherence. In the classical case, we derive measurement correlations from conditional probabilities, which yields quantitative statements about the parameter regime in which the detection scheme works well. Moreover, we demonstrate that not only the occupations of the double quantum dot may exhibit strong correlations with the detector current but also the corresponding current. The quantum mechanical solution shows that the backaction of the measurement tends to localize the electrons on the double quantum dot and, thus, significantly reduces the corresponding current. Furthermore, it provides the effective parameters of the classical treatment. It turns out that already the classical description is adequate for most operating regimes.

[1] R. Hussein, J. Gómez-García, and S. Kohler,

Phys. Rev. B 90, 155424 (2014).