Strong coupling of a qubit to shot noise

TL;DR

This paper investigates how strong coupling between a charge qubit and shot noise affects quantum coherence, revealing regimes where oscillations slow down or halt due to dissipative effects and phase transitions.

Contribution

It provides a nonperturbative analysis of the impact of strong detector-dot interactions on qubit coherence and identifies regimes of classical and quantum overdamping.

Findings

Strong coupling slows down and halts coherent oscillations.

Identification of classical and quantum overdamping regimes.

Competition between dissipative phase transition and shot noise effects.

Abstract

We perform a nonperturbative analysis of a charge qubit in a double quantum dot structure coupled to its detector. We show that strong detector-dot interaction tends to slow down and halt coherent oscillations. The transitions to a classical and a low-temperature quantum overdamping (Zeno) regime are studied. In the latter, the physics of the dissipative phase transition competes with the effective shot noise.