Observation of Universal Noise Fluctuations in Graphene

LTL Quantum Physics Seminar (Nanotalo). Speaker: Mr. Teemu Elo (Aalto University, Finland).

Mesoscopic conductors exhibit time-independent fluctuations of conductance in response to varying scattering configuration, for example due to external magnetic field or gate voltage. This phenomenon, known as universal conductance fluctuations (UCF), has been studied over decades both theoretically and experimentally in various systems including graphene [1]. However, in addition to UCF a similar phenomenon, namely universal noise fluctuations (UNF), is expected to occur in the shot noise power of mesoscopic conductors [2], although it has not been previously observed experimentally. We have studied both UCF and UNF in micron-sized graphene and present our experimental observations together with results from tight-binding simulations and theory predictions, all showing good agreement with each other.

[1] D.W. Horsell et al. Solid State Commun. 149, 1041 (2009).
[2] M.J.M. De Jong and C.W.J. Beenakker, Phys. Rev. B 46, 13400 (1992).