Electronic transmittance phase extracted from mesoscopic interferometers

Date
2012
Advisor
Instructor
Source Title
Nanoscale Research Letters
Print ISSN
19317573
Electronic ISSN
Publisher
Volume
7
Issue
Pages
Language
English
Type
Article
Journal Title
Journal ISSN
Volume Title
Abstract

The usual experimental set-up for measuring the wave function phase shift of electrons tunneling through a quantum dot (QD) embedded in a ring (i.e., the transmittance phase) is the so-called 'open' interferometer as first proposed by Schuster et al. in 1997, in which the electrons back-scattered at source and the drain contacts are absorbed by additional leads in order to exclude multiple interference. While in this case one can conveniently use a simple two-path interference formula to extract the QD transmittance phase, the open interferometer has also a number of draw-backs, such as a reduced signal and some uncertainty regarding the effects of the extra leads. Here we present a meaningful theoretical study of the QD transmittance phase in 'closed' interferometers (i.e., connected only to source and drain leads). By putting together data from existing literature and giving some new proofs, we show both analytically and by numerical simulations that the existence of phase lapses between consecutive resonances of the 'bare' QD is related to the signs of the corresponding Fano parameters - of the QD + ring system. More precisely, if the Fano parameters have the same sign, the transmittance phase of the QD exhibits a π lapse. Therefore, closed mesoscopic interferometers can be used to address the 'universal phase lapse' problem. Moreover, the data from already existing Fano interference experiments from Kobayashi et al. in 2003 can be used to infer the phase lapses. © 2012 Tolea et al.

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Keywords
Aharonov-Bohm interferometers, Phase lapse problem, Phase measurement, Aharonov-Bohm interferometers, Back-scattered, Drain contacts, Fano interference, Fano parameters, Mesoscopic interferometers, Multiple interferences, Phase lapse problem, Ring systems, Source and drains, Theoretical study, Transmittance phase, Interference suppression, Phase measurement, Superconducting materials, Interferometers
Citation
Published Version (Please cite this version)