Universal Braess paradox in open quantum dots

TL;DR

This paper demonstrates the universal presence of the Braess paradox in chaotic quantum dots, showing that adding capacity can reduce conductance due to quantum interference effects and symmetry breaking.

Contribution

It provides analytical and numerical evidence of the Braess paradox in quantum dots, revealing novel quantum interference phenomena and transitions related to magnetic crossover.

Findings

Braess paradox occurs in quantum dots, reducing conductance with increased capacity.

Weak localization shows a saturation minimum indicating the paradox.

Quantum interference can dominate classical conductance, affecting Fano factor behavior.

Abstract

We present analytical and numerical results that demonstrate the presence of the Braess paradox in chaotic quantum dots. The paradox that we identify, originally perceived in classical networks, shows that the addition of more capacity to the network can suppress the current flow in the universal regime. We investigate the weak localization term, showing that it presents the paradox encoded in a saturation minimum of the conductance, under the presence of hyperflow in the external leads. In addition, we demonstrate that the weak localization suffers a transition signal depending on the overcapacity lead and presents an echo on the magnetic crossover before going to zero due to the full time-reversal symmetry breaking.We also show that the quantum interference contribution can dominate the Ohm term in the presence of constrictions and that the corresponding Fano factor engenders an anomalous behavior