Extended Data Fig. 4: Upstream noise and Fano factor for newly engineered fractional states 2/3 − 1/3 = 1/3 and 2/3 − 4/15 = 2/5.
From: Shot noise does not always provide the quasiparticle charge
a,b, Spectral density of upstream current noise, measured at an upstream amplifier 70 µm distant from the source hot-spot. Unlike ubiquitous 1/3 and 2/5 modes, the interface 2/3b − 1/3g = 1/3int and 2/3b − 4/15g = 2/5int modes are expected to have negative or zero thermal conductance (Kxy); hence, they carry topological neutral modes. Note that 4/15 is a new quantum Hall state, which we could stabilize only by gating in a few bulk-gate devices. c,d, Spectral density of downstream current noise for 1/3int at t ≈ 0.63 and for 2/5int at t ≈ 0.56 when the QPC is set at symmetric configuration. Blue dots are the measured data and black solid lines are the fit. Estimated Fano factors are close to 2/3, the bulk filling factor. Schematics in the respective inset describe the interface mode incident on the QPC and the corresponding bulks.
