Shot noise does not always provide the quasiparticle charge

Sourav Biswas, Rajarshi Bhattacharyya, Hemanta Kumar Kundu, Ankur Das, Moty Heiblum*, Vladimir Umansky, Moshe Goldstein, Yuval Gefen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

The fractional charge of quasiparticles is a fundamental feature of quantum Hall effect states. The charge—important in characterizing the state and in interference experiments—has long been measured via shot noise at moderate temperatures, with the Fano factor revealing the charge of the quasiparticles. However, at sufficiently low temperatures of ~10 mK, we previously found that the Fano factor is instead equal to the bulk filling factor. Noise with this pattern was also observed on intermediate conductance plateaux in the transmission of the quantum point contact, where shot noise is not expected. Here, we extend this low-temperature behaviour of the Fano factor to a situation where the edge modes do not sit at the physical edge of the device but instead reside in an artificially constructed interface at the boundary between two adjoining quantum Hall effect states: the tested state and a different state. We attribute the unexpected shot noise behaviour to upstream neutral modes that proliferate at the lowest spinless Landau level. We present a theoretical approach based on an interplay between charge and neutral modes that hints at the origin of the universal Fano factor.

Original languageEnglish
Pages (from-to)1476-1481
Number of pages6
JournalNature Physics
Volume18
Issue number12
DOIs
StatePublished - Dec 2022

Funding

FundersFunder number
Directorate for Defense Research and Development3427/21
Federal German Ministry for Education and Research713534
Israel Planning and Budgeting Committee and Weizmann Institute of Science, Israel Dean of Faculty
National Science FoundationDMR- 2037654, I-1505-303.10/2019
Seventh Framework Programme
Koshland Foundation
European Research Council713351
Minerva Foundation
Deutsche ForschungsgemeinschaftMI 658/10-2, RO 2247/11-1
German-Israeli Foundation for Scientific Research and DevelopmentI-118-303.1-2018
United States-Israel Binational Science Foundation2020072, 2016224, CRC 183
Israel Science Foundation

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