Tunable pseudogap Kondo effect and quantum phase transitions in Aharonov-Bohm interferometers

TL;DR

This paper investigates how magnetic flux in an Aharonov-Bohm ring with two quantum dots can induce a pseudogap Kondo effect and quantum phase transitions, revealing complex interference and many-body phenomena.

Contribution

It introduces a tunable setup for observing pseudogap Kondo physics and quantum phase transitions via flux-controlled density of states in an Aharonov-Bohm interferometer.

Findings

Flux-dependent density of states vanishes at Fermi energy for specific flux values

Conductance and phase shifts reveal quantum phase transitions

Clear signatures of Kondo to non-Kondo ground state transitions

Abstract

We study two quantum dots embedded in the arms of an Aharonov-Bohm ring threaded by a magnetic flux. The system can be described by an effective one-impurity Anderson model with an energy- and flux-dependent density of states. For specific values of the flux, this density of states vanishes at the Fermi energy, yielding a controlled realization of the pseudogap Kondo effect. The conductance and transmission phase shifts reflect a nontrivial interplay between wave interference and interactions, providing clear signatures of quantum phase transitions between Kondo and non-Kondo ground states.