Quantum impurity approach to a coupled qubit problem

TL;DR

This paper models two qubits coupled via a finite 1D cavity using the double-Kondo model, calculating ground state properties and revealing how effective interactions can probe the Kondo length scale.

Contribution

It establishes a mapping of a coupled qubit system to the double-Kondo model and computes key ground state properties at the Toulouse point.

Findings

Ground state energy and correlations computed at zero temperature.

Effective interactions reveal the Kondo length scale.

Mapping provides insights into qubit-cavity and quantum wire physics.

Abstract

We consider a system of two qubits at the ends of a finite length 1D cavity. This problem is mapped onto the double-Kondo model which is also shown to describe the low energy physics of a finite length quantum wire with resonant levels at its ends. At the Toulouse point the ground state energy and the average populations and correlations of the qubits or resonant levels at zero temperature are computed. These results show that the effective interactions between the qubits or resonant levels can be used to probe their associated Kondo length scale.