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Tomonaga-Luttinger liquid nature of copropagating spin-up and spin-down quantum Hall edge channels splits an electron excitation into fast and slow excitations. Previous works identified the fractionalization process by injecting a spin-up or spin-down excitation into one of the copropagating channels and measured the resultant multiple excitations [1]. On the other hand, this work studies the fractionalization of a spin-up and spin-down superposition state prepared in the interacting channels [2,3]. We measured the interference of the fractionalized excitations in a Mach-Zehnder interferometer (MZI) employing interacting copropagating channels as the interference paths [Fig. 1]. The observed interference visibility oscillates as a function of the voltage bias applied between the channels, showing the “lobe structure,” which indicates the signature of the second-order interference in the one-way MZI. The lobe structure manifests the phase evolutions of the fractionalized excitations different from each other, reflecting the difference between their speeds. This work was supported by KAKENHI Grant No. JP22H00112, 19H05603, and 24H00827.

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Masayuki Hashisaka, ISSP, University of Tokyo
Seminar Room of the Institute of Physics II
Contact: Erwann / Matteo