Controlled dephasing in single-dot Aharonov-Bohm interferometers

TL;DR

This paper investigates how a nearby quantum dot influences dephasing and interference patterns in a mesoscopic Aharonov-Bohm interferometer, revealing controlled dephasing effects due to electron interactions and bias.

Contribution

It introduces a theoretical framework for analyzing dephasing in quantum dot interferometers considering electron interactions and bias effects, aligning with experimental observations.

Findings

Increased bias on the detector reduces Fano resonance and Aharonov-Bohm oscillation amplitudes.

The imaginary part of the self-energy explains the dephasing behavior.

Theoretical results match experimental data by Buks et al.

Abstract

We study the Fano effect and the visibility of the Aharonov-Bohm oscillations for a mesoscopic interferometer with an embedded quantum dot in the presence of a nearby second dot. When the electron-electron interaction between the two dots is considered the nearby dot acts as a charge detector. We compute the currents through the interferometer and detector within the Keldysh formalism and the self-energy of the non-equilibrium Green functions is found up to the second order in the interaction strength. The current formula contains a correction to the Landauer-B\"{uttiker} formula. Its contribution to transport and dephasing is discussed. As the bias applied on the detector is increased, the amplitude of both the Fano resonance and Aharonov-Bohm oscillations are considerably reduced due to controlled dephasing. This result is explained by analyzing the behavior of the imaginary part of the self-energy as a function of energy and bias. We investigate as well the role of the ring-dot coupling. Our theoretical results are consistent to the experimental observation of Buks {\it et al.} [Nature {\bf 391}, 871 (1998)].