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Exponential sensitivity to dephasing of electrical conduction through a quantum dot

J. Tworzydlo·A. Tajic·H. Schomerus·P. W. Brouwer·C. W. J. Beenakker
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Abstract

According to random-matrix theory, interference effects in the conductance of a ballistic chaotic quantum dot should vanish $\propto(τ_ϕ/τ_{D})^{p}$ when the dephasing time $τ_ϕ$ becomes small compared to the mean dwell time $τ_{D}$. Aleiner and Larkin have predicted that the power law crosses over to an exponential suppression $\propto\exp(-τ_{E}/τ_ϕ)$ when $τ_ϕ$ drops below the Ehrenfest time $τ_{E}$. We report the first observation of this crossover in a computer simulation of universal conductance fluctuations. Their theory also predicts an exponential suppression $\propto\exp(-τ_{E}/τ_{D})$ in the absence of dephasing -- which is not observed. We show that the effective random-matrix theory proposed previously for quantum dots without dephasing explains both observations.

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J. Tworzydlo, A. Tajic, H. Schomerus, P. W. Brouwer, C. W. J. Beenakker. 2004-07-20. Exponential sensitivity to dephasing of electrical conduction through a quantum dot. https://doi.org/10.1103/physrevlett.93.186806

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