Masayuki Hashisaka

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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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ISSP, University of Tokyo
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