Europhys. Lett.
Volume 66, Number 5, June 2004
Page(s) 624 - 630
Section General
Published online 01 May 2004
Europhys. Lett., 66 (5) , pp. 624-630 (2004)
DOI: 10.1209/epl/i2003-10257-1

Entangled electronic state via an interacting quantum dot

G. León1, 2, O. Rendon1, 3, H. M. Pastawski4, V. Mujica5 and E. Medina1, 2

1  Centro de Física, Instituto Venezolano de Investigaciones Científicas, IVIC Apartado 21827, Caracas 1020 A, Venezuela
2  Departamento de Física, Facultad de Ciencias, Universidad Central de Venezuela Caracas, Venezuela
3  Departamento de Física, FACYT, Universidad de Carabobo Valencia, Edo. Carabobo, Venezuela
4  Facultad de Matemática, Astronomía y Física, LaNAIS de RMS CONICET Universidad Nacional de Córdoba - Ciudad Universitaria, 5000 Córdoba, Argentina
5  Departamento de Química, Facultad de Ciencias, Universidad Central de Venezuela Caracas, Venezuela

(Received 17 November 2003; accepted in final form 6 April 2004)

We study a device for entangling electrons as co-tunneling occurs through a quantum dot where on-site electron-electron interactions U are in place. The main advantage of this device is that single-particle processes are forbidden by energy conservation as proposed by Oliver et al. (Phys. Rev. Lett. 88 (2002) 7901). Within this model we calculated the two-electron transition amplitude, in terms of the T-matrix, to all orders in the coupling to the dot, and consider a finite lead bandwidth. The model filters singlet entangled pairs with the sole requirement of Pauli principle. Feynman paths involving consecutive and doubly occupied dot interfere destructively and produce a transition amplitude minimum at a critical value of the onsite repulsion U. Singlet filtering is demonstrated as a function of a gate voltage applied to the dot with a special resonance condition when the dot levels are symmetrically placed about the input lead energy.

03.65.Ud - Entanglement and quantum nonlocality (e.g. EPR paradox, Bell's inequalities, GHZ states, etc.).
73.63.Kv - Quantum dots.

© EDP Sciences 2004