High-efficiency Cooper pair splitting demonstrated by two-particle conductance resonance and positive noise cross-correlation

Entanglement, being at the heart of the Einstein-Podolsky-Rosen (EPR) paradox, is a necessary ingredient in processing quantum information. Being non-local, its demonstration for two, separated, entangled particles must involve simultaneous, non-local, measurements. While fully entangled photons are readily provided by low efficiency parametric down conversion of higher energy photons, such a feat is not readily available for electrons. On the other hand, starting with Cooper pairs in superconductors - being composites of two fully entangled electrons - and splitting them adiabatically, is a promising means to create entangled electrons. In this talk I will show how we fabricate such an electron splitter by contacting a superconductor strip at the center of a suspended InAs nanowire; terminated at both ends with two normal metallic drains. Intercepting each half of the nanowire by a gate-induced resonant tunneling quantum dot strongly impedes the flow of Cooper pairs due to large charging (addition) energy, while still permitting passage of single electrons. I will provide conclusive evidence of extremely high efficiency Cooper pairs splitting by the following observations: (i) Simultaneous split electrons conductance resonance in both sides of the nanowire; (ii) Time coincidence of split electrons via observing positive cross-correlation of currents fluctuations in the two drains; and (iii) The actual charge of the injected quasiparticles’ via shot noise measurements.

References:
‘High-efficiency Cooper pair splitting demonstrated by two-particle conductance resonance and positive noise cross-correlation’
Anindya Das, Yuval Ronen, MotyHeiblum, Diana Mahalu, Andrey V. Kretinin and HadasShtrikman. 
Nature Communications, 3, 1165 (2012) (arXiv:1205.2455).