Efficiency of mesoscopic detectors.
We consider a mesoscopic measuring device whose conductance is sensitive to the state of a two-level system. The detector is described with the help of its scattering matrix. Its elements can be used to calculate the relaxation and decoherence times of the system, and determine the characteristic time for a reliable measurement. We derive conditions needed for an efficient ratio of decoherence and measurement times. To illustrate the theory we discuss the distribution function of the efficiency of an ensemble of open chaotic cavities.
Pilgram
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Département de Physique Théorique, Université de Genève, 24, quai Ernest-Ansermet, 1211 Genève 4, Switzerland.
Büttiker
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