We have studied scattering of two identical particles [1, 2]. The device consists of one input lead and output leads attached to a quantum dot. The movement of two fermions is without interaction in the leads but exist repulsion U when the dot is doubly occupied. In this device, one may avoid both single and triple processes with putting certain values in the leads energy. Within this model We have done formal derivations for transition amplitudes, in terms of the T-matrix, to second orders in the coupling to the dot V_coupling and consider a finite lead bandwidth, V. In fact, we put V_coupling << V. At T = 0 K, the devices filters singlet entangled pairs if U ≠ 0. However, here the postselection is not used. Moreover, resonance structure for the singlet transition amplitude is studied as function of energy difference between the input lead and the dot single-particle state. In U = 0, there isn't tunneling and the two-fermion scattering matrix tend to the obtained by custom scattering matrix theory for noninteracting electrons. The first part of this work has been done in collaboration with Gladys León and Ernesto Medina D.

[1] Oliver W. D., F. Yamaguchi, and Y. Yamamoto, Phys. Rev. Lett. vol. 63, 037901 (2002).
[2] G. León, O. Rendón, H. M. Pastawski, V. Mujica, and E. Medina, Europhys. Lett. vol. 66, 624 (2004).
[3] M. Büttiker, Y. Imry, R. Landauer, and S. Pinhas, Phys. Rev. B vol. 31, 6207(1985).