Detection of fractional quantum Hall states by entropy-sensitive measurements

Published

March 17, 2025

Author(s)

Nishat Sultana, Robert Rienstra, K Watanabe, T Taniguchi, Joseph Stroscio, Nikolai Zhitenev, D Feldman, Fereshte Ghahari Kermani

Abstract

Measurements of the thermopower of a clean two-dimensional electron system is directly proportional to the entropy per charge carrier1 which can probe strongly interacting quantum systems ranging from black holes2 to the fractional quantum Hall effect (FQHE)3,4. This makes thermopower a unique technique to probe the non-Abelian quasiparticle statistics which gives rise to excess entropy in certain even denominator fractional quantum Hall (FQH) states5,6. In this article, we report the first magneto-thermopower detection of FQH states in Bernal stacked bilayer graphene (BLG) including even denominator states at relatively low magnetic fields. Our data indicates that thermopower as a measure of entropy is a far more sensitive probe of correlated states compared to resistivity measurements. We report on the observation of new even denominator FQH states at the zeroth Landau level (LL) and clear evidence for unexpected even denominator states in the N=2 and N=3 LLs in this system. The magnetic field dependence of thermopower provides convincing evidence for the non- Abelian nature of the state observed at filling factor ν =1/2. The demonstrated capabilities of the thermopower measurements coincides with the intense interest in non-Abelian quasiparticles for fault tolerant quantum computation7,8 elevating bilayer graphene as a promising platform for these applications.

Citation

Nature Physics

Pub Type

Journals

Download Paper

https://doi.org/10.1038/s41567-025-02813-z

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Keywords

Thermopower, fractional quantum Hall effect, graphene, bilayer graphene

Citation

Sultana, N. , Rienstra, R. , Watanabe, K. , Taniguchi, T. , Stroscio, J. , Zhitenev, N. , Feldman, D. and Ghahari Kermani, F. (2025), Detection of fractional quantum Hall states by entropy-sensitive measurements, Nature Physics, [online], https://doi.org/10.1038/s41567-025-02813-z, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=957202 (Accessed April 4, 2025)