Nonlocal interference and Hong-Ou-Mandel collisions of single Bogoliubov quasiparticles

Abstract

We consider a device which allows one to create and probe single Majorana fermions, in the form of Bogoliubov quasiparticles. It is composed of two counterpropagating edge channels, each put in proximity with a superconducting region where Andreev reflection operates, and which thus converts electrons into Bogoliubov quasiparticles. The edge channels then meet at a quantum point contact where collisions can be achieved. A voltage-biased version of the setup was studied [C. W. J. Beenakker, Phys. Rev. Lett. 112, 070604 (2014)] and showed nonlocal interference phenomena and signatures of Bogoliubov quasiparticle collisions in the high-frequency noise characteristics at the output, constituting an evidence of the Majorana fermion nature of these excitations. Here, voltage-biased leads are replaced by single-electron sources in order to achieve collisions of single Bogoliubov quasiparticles, with the major advantage that zero-frequency noise measurements are sufficient to access the intimate nature of Bogoliubov wave packets. We compute the injection parameters of the source, and go on to investigate the Hanbury-Brown and Twiss and Hong-Ou-Mandel signal at the output, as a function of the mixing angle which controls the electron/hole component of the Bogoliubov wave packet. In particular, information on the internal structure of the Bogoliubov quasiparticle can be recovered when such a quasiparticle collides with a pure electron. Experimental feasibility with singlet or triplet superconductors is discussed.