Signatures of Quantum Non-Locality in a Graphene Polarizer-Analyzer Experiment

Mesoscopic conductance fluctuations are a characteristic signature of phase-coherent transport in small conductors, exhibiting universal character independent of system details. In this work, however, we demonstrate a pronounced breakdown of this universality, due to the interplay of local and non-local phenomena in phase-coherent transport. Our experiments are performed in a polarizer-analyzer geometry, in which an external spin-orbit coupling is induced in graphene by covering a portion of it with a micromagnet, and probing conduction at some distance from this polarizer. The non-local nature of this measurement is manifested through the appearance of giant conductance fluctuations, with amplitude much larger than $e^2/h$, providing a powerful demonstration of the manner in which transport may be strongly impacted by quantum non-locality.