Observation of e/4 Charge at ν = 1/2 in a Wide GaAs Quantum Well
Even-denominator fractional quantum Hall states (FQHSs) fall outside the standard Laughlin’s and Jain’s odd-denominator hierarchy. They are of intense current interest because they may exhibit non-Abelian topological order and therefore have applications in topological quantum computation. In this Letter, we study the FQHS at filling factor ν=1/2, observed in a two-dimensional electron system confined to a wide GaAs quantum well. Unlike other even-denominator FQHSs, this state is stabilized at the lowest Landau level and has an energy gap about 10 times larger than the widely studied ν=5/2 FQHS. Moreover, a recently observed pair of daughter FQHSs theoretically predicted the parent ν=1/2 FQHS to be a non-Abelian state. Here, we report shot-noise measurements of partitioned quasiparticles at ν=1/2 by an etch-defined quantum point contact (QPC). Our measurements were performed on two nominally identical devices in two independent experimental setups. Analysis of the shot noise in the weak-backscattering regime (of the QPC) reveals quasiparticles with charge e/4, consistent with a non-Abelian order, although it does not rule out an Abelian order. These observations provide a clear benchmark for future studies aimed at probing the topological order of the ν=1/2 FQHS and its quasiparticles’ exchange statistics.
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Alkalay, T., Hajigeorgiou, E., Gupta, A., Senapati, T., Tiwari, P., Tai, C. T., Singh, S. K., Baldwin, K. W., Pfeiffer, L. N., Shayegan, M., Banerjee, M., & Heiblum, M. (2026). Observation of e/4 Charge at ν = 1/2 in a Wide GaAs Quantum Well. Physical Review Letters, 137(13), Article 136503. https://doi.org/10.1103/c73x-q4z7
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2-s2.0-105051932268
Weizmann Institute of Science Israel
École Polytechnique Fédérale de Lausanne
School of Engineering and Applied Science
Weizmann Institute of Science Israel
Weizmann Institute of Science Israel
School of Engineering and Applied Science
School of Engineering and Applied Science
School of Engineering and Applied Science
School of Engineering and Applied Science
School of Engineering and Applied Science
2026-09-25
137
13
136503
REVIEWED
EPFL
| Funder | Funding(s) | Grant Number | Grant URL |
IPHYS director | |||
National Science Foundation (NSF) | DMR 2104771 | ||
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