Telegraph Noise in Coupled Quantum Dot Circuits Induced by a Quantum Point Contact

TL;DR

This paper investigates how a quantum point contact used for charge detection induces telegraph noise and inelastic transitions in coupled quantum dot circuits, revealing a nonequilibrium transition affecting quantum information applications.

Contribution

It demonstrates the back action of quantum point contact charge sensing causing telegraph noise and inelastic transitions, and identifies a transition from atomic to molecular behavior in quantum dots.

Findings

Quantum point contact induces telegraph noise in quantum dot circuits.

Inelastic transitions are triggered by the quantum point contact.

A transition from atomic to molecular behavior is observed.

Abstract

Charge detection utilizing a highly biased quantum point contact has become the most effective probe for studying few electron quantum dot circuits. Measurements on double and triple quantum dot circuits is performed to clarify a back action role of charge sensing on the confined electrons. The quantum point contact triggers inelastic transitions, which occur quite generally. Under specific device and measurement conditions these transitions manifest themselves as bounded regimes of telegraph noise within a stability diagram. A nonequilibrium transition from artificial atomic to molecular behavior is identified. Consequences for quantum information applications are discussed.