Backaction Dephasing by a Quantum Dot Detector

TL;DR

This paper derives an analytical expression for backaction dephasing caused by a quantum dot detector, showing how charge noise influences dephasing rates under various conditions, with implications for quantum measurement accuracy.

Contribution

It provides the first explicit analytical formula for backaction dephasing due to charge noise in a quantum dot detector, linking it to inelastic electron scattering.

Findings

Dephasing rate depends on QDD energy level and bias voltage at low bias.

Dephasing rate saturates and becomes insensitive to bias at high bias.

Charge noise induces dephasing through inelastic electron-electron scattering.

Abstract

We derive an analytical expression for the backaction dephasing rate, which characterizes the disturbance induced by coupling with an environment containing a quantum dot detector (QDD). In this letter, we show that charge noise induces backaction dephasing in an explicit form. In the linear transport regime through a QDD, this backaction dephasing induced by charge noise can be explained as a relaxation by an inelastic electron-electron scattering in Fermi liquid theory. In the low bias voltage regime, the increase or decrease of dephasing rate depends on the QDD energy level, the linewidth functions, and how to apply the bias voltage. Unlike quantum point contact, the dephasing rate would be insensitive to the bias voltage in a high bias voltage regime because of the saturation of charge noise in a QDD.