Nonlocality of Dephasing in a Charge Qubit Interacting with a Quantum Point Contact Beam Collider

TL;DR

This paper explores how dephasing in a charge qubit caused by a quantum point contact beam collider exhibits nonlocal behavior, with interference restored under certain conditions, highlighting the role of Fermi statistics and entangled electron pairs.

Contribution

It reveals the nonlocal nature of dephasing in a charge qubit interacting with a quantum point contact, especially under conditions of electron collision and entanglement.

Findings

Dephasing is suppressed when electrons undergo two-electron collisions.

Interference can be fully restored by biasing inputs identically.

Detection properties for entangled electron pairs are characterized.

Abstract

We investigate the charge-detection-induced dephasing of a charge qubit interacting with an electronic beam collider composed of a quantum point contact. We report that, while the qubit is dephased by the partitioned beam of uncorrelated electrons, the interference of the qubit is fully restored when the two inputs are identically biased so that all the electrons suffer two-electron collision. This phenomenon is related to Fermi statistics and illustrates the peculiar nonlocality of dephasing. We also describe detection properties for the injection of entangled electron pairs.