Figure 1: Sketch of electron fractionalization and measured sample.

(a) Due to interchannel interaction on propagation length l, an electronic wave packet emitted on the outer edge channel splits in a charge mode (dashed blue oval) propagating at velocity v₊ and a neutral mode (red oval) with velocity v₋ separated by time τ_s. The interaction region is represented by a capacitive coupling between the edges in the dashed black box. Negative (positive) charge pulses are represented in blue (red). At the output of the interaction region, the electron on the outer channel has fractionalized in two pulses carrying charge e/2. A dipolar current trace has been generated in the inner channel. (b) Modified scanning electron microscope picture of the sample. The electron gas is represented in blue, the edge channels by blue lines and metallic gates are in gold. The emitters are placed at inputs 1 and 2 of the QPC used as an electronic beam splitter (with a 3μ distance between emitter and QPC). Charge emission on the outer channel is triggered by the excitation voltage V_exc,i. The dot to edge transmission of source i is tuned by the gate voltage V_g,i. The central QPC gate voltage V_qpc can be tuned to partition either the outer or inner edge channel. Average a.c. current measurements are performed on the splitter output 4, low-frequency noise spectrum measurements S₃₃ are performed on output 3.