Dephasing and the Orthogonality Catastrophe in Tunneling through a Quantum Dot: the ``Which Path?'' Interferometer

TL;DR

This paper investigates how a quantum point contact near a quantum dot in an Aharonov-Bohm ring causes dephasing and orthogonality catastrophe, affecting electron interference patterns.

Contribution

It provides a detailed analysis of dephasing and orthogonality effects in a 'Which Path?' interferometer with a quantum dot and QPC, highlighting the interplay between real and virtual electron-hole pair creation.

Findings

Dephasing suppresses Aharonov-Bohm oscillations.

Orthogonality catastrophe contributes to interference suppression.

Both real and virtual electron-hole pairs impact transport.

Abstract

The ``Which Path?'' interferometer consists of an Aharonov-Bohm ring with a quantum dot (QD) built in one of its arms, and an additional quantum point contact (QPC) located close to the QD. The transmission coefficient of the QPC depends on the charge state of the QD. Hence the point contact causes controllable dephasing of transport through the QD, and acts as a measurement device for which path an electron takes through the ring. We calculate the suppression of the Aharonov-Bohm oscillations which is caused both by dephasing and by the orthogonality catastrophe, i.e., respectively, by real and virtual electron-hole pair creation at the QPC.