Bilayer excitons in the Laughlin fractional quantum Hall state

Nature Physics (2026) Cite this article The Laughlin state provides a description for a universal class of fractional quantum Hall effects that arise in two-dimensional electron systems subjected to strong perpendicular magnetic fields. Conventionally described by a single-component wavefunction, the Laughlin state features fractionally charged quasiparticles that result from correlations within one electronic layer. Here we explore a bilayer situation with interlayer Coulomb coupling between two intralayer Laughlin states that creates excitons between them in a quantum Hall graphene structure. Although quasiparticle excitations typically exhibit charge gaps of tens of kelvins, we observe that this energy scale is lowered through interlayer excitonic pairing between quasiparticles and quasiholes. We identify these excitons in our transport measurements and show that they belong to a category of charge-neutral anyons, thus opening an avenue for investigating exotic quantum statistics and phases of matter.This is a preview of subscription content, access via your institution Access Nature and 54 other Nature Portfolio journals Get Nature+, our best-value online-access subscription $32.99 / 30 days cancel any timeSubscribe to this journal Receive 12 print issues and online access $259.00 per yearonly $21.58 per issueBuy this articleUSD 39.95Prices may be subject to local taxes which are calculated during checkoutThe data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request. Source data are provided with this paper.Luttinger, J. Fermi surface and some simple equilibrium properties of a system of interacting fermions. Phys. Rev. 119, 1153 (1960).Article ADS MathSciNet Google Scholar Nozieres, P. & Pines, D. Theory of Quantum Liquids: Normal Fermi Liquids (CRC Press, 2018).Halperin, B. I. & Jain, J. K.

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Lett. 56, 742 (1986).Article ADS Google Scholar Download referencesThis material is based on the work supported by the Air Force Office of Scientific Research (Award No. FA9550-23-1-0482). N.J.Z., R.Q.N. and J.I.A.L. acknowledge support from the Air Force Office of Scientific Research. N.J.Z. acknowledges partial support from the Jun-Qi fellowship. R.Q.N. and J.I.A.L. acknowledge partial support from the National Science Foundation EPSCoR Program (NSF Award No. OIA-2327206). Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect those of the National Science Foundation. This work was performed in part at the Aspen Center for Physics, which is supported by a grant from the Alfred P. Sloan Foundation (Grant No. G-2024-22395). A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by National Science Foundation (Cooperative Agreement No. DMR-1157490) and the State of Florida. N.K.-B. and D.E.F. were supported in part by the National Science Foundation (Grant No. DMR-2204635). S.A. acknowledges support from Kuwait University. K.W. and T.T. acknowledge support from the JSPS (KAKENHI Grant Nos. 21H05233 and 23H02052) and the World Premier International Research Center Initiative, MEXT, Japan. Part of this work was enabled by the use of pyscan (github.com/sandialabs/pyscan), scientific measurement software made available by the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the US Department of Energy.These authors contributed equally: Ron Q. Nguyen, Naiyuan J. Zhang, Navketan Khurana-Batra.Department of Physics, Brown University, Providence, RI, USARon Q. Nguyen, Naiyuan J. Zhang, Navketan Khurana-Batra, Sarah Alkidim, Xiaoxue Liu, D. E. Feldman & J. I. A. LiBrown Theoretical Physics Center, Brown University, Providence, RI, USANavketan Khurana-Batra & D. E. FeldmanResearch Center for Electronic and Optical Materials, National Institute for Materials Science, Tsukuba, JapanKenji WatanabeResearch Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, JapanTakashi TaniguchiDepartment of Physics, University of Texas at Austin, Austin, TX, USAJ. I. A. LiSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarN.J.Z. and J.I.A.L. conceived the project. N.J.Z., R.Q.N. and X.L. fabricated the device. N.J.Z., R.Q.N. and S.A. performed the measurements. N.K.-B. and D.E.F. provided theoretical input. K.W. and T.T. provided the material. N.J.Z., R.Q.N., N.K.-B., S.A., D.E.F. and J.I.A.L wrote the paper together.Correspondence to J. I. A. Li.The authors declare no competing interests.Nature Physics thanks the anonymous reviewers for their contribution to the peer review of this work.Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.(a) Schematic phase diagram of a quantum Hall bilayer, parameterized by νtotal and Δν. Black solid lines mark the expected trajectories of layer-decoupled FQH states belonging to the Jain sequence. The red solid line denotes the equal-density line, where the filling factors in the two graphene layers are equal, ν1 = ν2. Red circles indicate the expected locations of Jain states along this line. (b-c) Parallel-flow conductance GPF (top) and drag ratio Idrag/Idrive (bottom) measured along the equal-density line as a function of νtotal at (b) B = 20 T and (c) B = 28 T. The emergence of FQH states is signaled by vanishing GPF, whereas exciton pairing is manifested by perfect drag response with Idrag/Idrive = 1. Black vertical dotted lines mark the expected positions of Jain-sequence FQH states, while the red vertical dotted line denotes a half filled Λ-level. The green dotted line marks the location of the two-component FQH state identified in previous works12,17,55.Longitudinal and Hall resistances, Rxx (top) and Rxy (bottom), of the drive (red) and drag (blue) layers measured along the equal-density line as a function of νtotal at (a) B = 30 T, (b) B = 25 T, (c) B = 18 T, and (d) B = 12 T. Black vertical dashed lines indicate the expected locations of the Laughlin states at νtotal = − 4/3 and − 2/3, as well as the (111) state at νtotal = − 1. An enhancement of drag response at ν1 = ν2 = − 1/3 is observed at B = 12 T (panel d).(a) Longitudinal (top) and Hall (bottom) resistances Rxx and Rxy of a double-layer device in a Hall bar geometry measured as a function of νtota at B = 18 T for drive (red) and drag (blue) layers. (b) Parallel-flow conductance GPF (top) and drag ratio Idrag/Idrive (bottom) of a double layer device in a Corbino geometry measured as a function of νtotal at B = 28 T.(a,b) Parallel-flow conductance GPF measured along the equal-density line of the Corbino-shaped device, shown (a) as a function of νtotal at B = 18 T and (b) as a color scale map with varying νtotal and B. FQH states occurring at integer and half-integer composite-fermion fillings are indicated by vertical dotted lines. Within the range − 4/3 − 2/3, the sequence with one interlayer flux attachment persists up to B = 18 T12.Supplementary text and Figs. 1–5.Source data for Fig. 1.Source data for Fig. 2.Source data for Fig. 3.Source data for Fig. 4.Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.Reprints and permissionsNguyen, R.Q., Zhang, N.J., Khurana-Batra, N. et al. Bilayer excitons in the Laughlin fractional quantum Hall state. Nat. Phys. 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