Europhys. Lett.
Volume 68, Number 1, October 2004
Page(s) 37 - 43
Section Atomic and molecular physics
Published online 01 September 2004
Europhys. Lett., 68 (1), pp. 37-43 (2004)
DOI: 10.1209/epl/i2004-10219-1

Quantum impurity approach to a coupled qubit problem

S. Camalet1, J. Schriefl1, 2, P. Degiovanni1 and F. Delduc1

1  CNRS-Laboratoire de Physique, Ecole Normale Supérieure de Lyon 46 allée d'Italie, 69007 Lyon, France
2  Institut für Theoretische Festkörperphysik - Universität Karlsruhe 76128 Karlsruhe, Germany

received 26 May 2004; accepted in final form 6 August 2004

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.

32.80.-t - Photon interactions with atoms.
72.10.Fk - Scattering by point defects, dislocations, surfaces, and other imperfections (including Kondo effect).
71.10.Pm - Fermions in reduced dimensions (anyons, composite fermions, Luttinger liquid, etc.).

© EDP Sciences 2004