Quantum criticality in a double quantum-dot system

TL;DR

This paper explores how double quantum-dot systems can realize a quantum-critical non-Fermi liquid state, demonstrating its robustness and proposing an experimental setup to observe this state through controlled charge transfer suppression.

Contribution

It shows the robustness of the quantum-critical state against asymmetries and proposes an experimental configuration to access this state in double quantum-dot systems.

Findings

Quantum critical state is robust against particle-hole asymmetry.

Charge transfer between dots destabilizes the critical point.

Proposed setup suppresses charge transfer to observe criticality.

Abstract

We discuss the realization of the quantum-critical non-Fermi liquid state, originally discovered within the two-impurity Kondo model, in double quantum-dot systems. Contrary to the common belief, the corresponding fixed point is robust against particle-hole and various other asymmetries, and is only unstable to charge transfer between the two dots. We propose an experimental set-up where such charge transfer processes are suppressed, allowing a controlled approach to the quantum critical state. We also discuss transport and scaling properties in the vicinity of the critical point.