Tuning decoherence with a voltage probe

TL;DR

This paper demonstrates how a voltage probe can be used to tune decoherence in a quantum interferometer, providing a controllable method to study quantum coherence loss in electronic systems.

Contribution

It introduces an experimental setup using an ohmic contact as a voltage probe to control decoherence in a Mach-Zehnder interferometer.

Findings

Quantum interference visibility up to 57% observed.

Decoherence increases with stronger connection to the voltage probe.

Tunable which-path detection demonstrated via gate voltage control.

Abstract

We present an experiment where we tune the decoherence in a quantum interferometer using one of the simplest object available in the physic of quantum conductors : an ohmic contact. For that purpose, we designed an electronic Mach-Zehnder interferometer which has one of its two arms connected to an ohmic contact through a quantum point contact. At low temperature, we observe quantum interference patterns with a visibility up to 57%. Increasing the connection between one arm of the interferometer to the floating ohmic contact, the voltage probe, reduces quantum interferences as it probes the electron trajectory. This unique experimental realization of a voltage probe works as a trivial which-path detector whose efficiency can be simply tuned by a gate voltage.