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Detecting weak coupling in mesoscopic systems with a nonequilibrium Fano resonance
Univ Buffalo, State Univ New York, Dept Elect Engn, Buffalo, NY 14260 USA..
Univ Buffalo, State Univ New York, Dept Elect Engn, Buffalo, NY 14260 USA..
Univ Buffalo, State Univ New York, Dept Elect Engn, Buffalo, NY 14260 USA.;Chiba Univ, Grad Sch Adv Integrat Sci, Inage Ku, 1-33 Yayoi Cho, Chiba 2638522, Japan..
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2016 (English)In: PHYSICAL REVIEW B, ISSN 2469-9950, Vol. 93, no 16, 165435Article in journal (Refereed) PublishedText
Abstract [en]

A critical aspect of quantum mechanics is the nonlocal nature of the wave function, a characteristic that may yield unexpected coupling of nominally isolated systems. The capacity to detect this coupling can be vital in many situations, especially those in which its strength is weak. In this work, we address this problem in the context of mesoscopic physics, by implementing an electron-wave realization of a Fano interferometer using pairs of coupled quantum point contacts (QPCs). Within this scheme, the discrete level required for a Fano resonance is provided by pinching off one of the QPCs, thereby inducing the formation of a quasibound state at the center of its self-consistent potential barrier. Using this system, we demonstrate a form of nonequilibrium Fano resonance (NEFR), in which nonlinear electrical biasing of the interferometer gives rise to pronounced distortions of its Fano resonance. Our experimental results are captured well by a quantitative theoretical model, which considers a system in which a standard two-path Fano interferometer is coupled to an additional, intruder, continuum. According to this theory, the observed distortions in the Fano resonance arise only in the presence of coupling to the intruder, indicating that the NEFR provides a sensitive means to infer the presence of weak coupling between mesoscopic systems.

Place, publisher, year, edition, pages
2016. Vol. 93, no 16, 165435
National Category
Condensed Matter Physics
URN: urn:nbn:se:uu:diva-297359DOI: 10.1103/PhysRevB.93.165435ISI: 000374950300017OAI: oai:DiVA.org:uu-297359DiVA: diva2:941880
Swedish Research Council
Available from: 2016-06-23 Created: 2016-06-22 Last updated: 2016-06-23Bibliographically approved

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Fransson, Jonas
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Materials Theory
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