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Broken unitarity and phase measurements in Aharonov-Bohm interferometers

O. Entin-Wohlman·A. Aharony·Y. Imry·Y. Levinson·A. Schiller
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Abstract

Aharonov-Bohm mesoscopic solid-state interferometers yield a conductance which contains a term $\cos(ϕ+β)$, where $ϕ$ relates to the magnetic flux. Experiments with a quantum dot on one of the interfering paths aim to relate $β$ to the dot's intrinsic Friedel transmission phase, $α_1$. For closed systems, which conserve the electron current (unitarity), the Onsager relation requires that $β=0$. For open systems, we show that $β$ depends in general on the details of the broken unitarity. Although it gives information on the resonances of the dot, $β$ is generally not equal to $α_1$. A direct relation between $β$ and $α_1$ requires specific ways of opening the system, which are discussed.

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O. Entin-Wohlman, A. Aharony, Y. Imry, Y. Levinson, A. Schiller. 2002-02-22. Broken unitarity and phase measurements in Aharonov-Bohm interferometers. https://doi.org/10.1103/physrevlett.88.166801

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