Shot Noise Fano Factor: Bulk or Edge Property

The quasiparticle charge in the Fractional Quantum Hall effect (FQHE) has long been measured via quantum shot-noise measurements. Here, we demonstrate that the standard Fano factor of shot noise (F=1 for integers), stemming from either weakly backscattered charged quasiparticle (in a QPC) at low temperature (T∼10 mK), with or without accompanying neutral modes, depends only on the bulk filling away from the QPC and not on the structure (and conductance) of the edge modes or the filling factor within the QPC constriction. We employed a novel method in which two different QHE bulks’ fillings are interfaced, thus giving birth to novel 1D chiral modes at the interface. The interface modes have an ‘effective filling’ (edge conductance), which is different from the filling of each of the interfacing bulks, and moreover, different from the filling within the QPC constriction. Our results are explained within a new theoretical paradigm for shot noise.