Decoherence effects on weak value measurements in double quantum dots

TL;DR

This paper investigates how decoherence influences weak value measurements in double quantum dots, revealing that measurement duration and decoherence interplay can either diminish or enhance weak values depending on system parameters.

Contribution

It provides a detailed analysis of decoherence effects on weak values in quantum dot systems, highlighting conditions for enhancement or reduction of weak values.

Findings

Weak values decrease for measurements longer than the decoherence time.

Shorter measurements show strong dependence on decoherence and backaction.

Classical readout frequency can sometimes enhance weak values.

Abstract

We study the effect of decoherence on a weak value measurement in a paradigm system consisting of a double quantum dot continuously measured by a quantum point contact. Fluctuations of the parameters controlling the dot state induce decoherence. We find that, for measurements longer than the decoherence time, weak values are always reduced within the range of the eigenvalues of the measured observable. For measurements at shorter time scales, the measured weak value strongly depends on the interplay between the decoherence dynamics of the system and the detector backaction. In particular, depending on the postselected state and the strength of the decoherence, a more frequent classical readout of the detector might lead to an enhancement of weak values.