Beam Splitter for Fermions using Crossed Andreev Reflection

The Hong-Ou-Mandel effect [1] in quantum optics demonstrates the uniquely quantum properties of light due to the bunching effect of two incident photons on a beam splitter. In non-equilibrium mesoscopic systems, quasiparticle currents composed of fermions exhibit anti-bunching effects analogous to the bunching of bosons. The equivalent to quantum optics intensity interferometry in mesoscopic systems is the study of shot noise via current-current fluctuations [2]. Separately, crossed Andreev reflection (CAR) is the effect of electronic quasiparticles incident on a superconductor that result in an outgoing hole in a non-injecting lead. Our proposed device utilizes multi-terminal NSN junctions with two incident normal currents which generate two outgoing CAR currents. These nonlocally generated currents, using a superconductor as a mesoscopic beam splitter, will enable fabrication of mesoscopic analogs to quantum optics interferometers using amorphous metallic and superconducting films.

[1] C. K. Hong, Z. Y. Ou, and L. Mandel, Phys. Rev. Lett. 59, 2044 (1987).

[2] Y. M. Blanter and M. Buttiker, Physics Reports 336, 1 (2000).