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arxiv: 2605.23613 · v1 · pith:NKXFRHY7new · submitted 2026-05-22 · 🪐 quant-ph · cond-mat.mes-hall

Non-Hermitian Landau Levels

Pith reviewed 2026-05-25 04:20 UTC · model grok-4.3

classification 🪐 quant-ph cond-mat.mes-hall
keywords non-HermitianLandau levelscomplex magnetic fieldbiorthogonal eigenstatesHarper-Hofstadter modelcomplex Lorentz forcesymmetric gauge
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The pith

Non-Hermitian Landau levels under a complex perpendicular magnetic field produce discretely spaced, highly degenerate complex spectra with biorthogonal eigenstates.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper formulates non-Hermitian Landau levels for two-dimensional systems placed in a complex perpendicular magnetic field. In the symmetric gauge it derives the discretely spaced and highly degenerate complex energy spectra together with the corresponding biorthogonal eigenstates. It also clarifies how non-unitary gauge transformations act in this setting. A non-Hermitian version of the Harper-Hofstadter lattice model is shown to reproduce the continuum results and to generate Gaussian wave-packet motion governed by semiclassical equations that include a complex Lorentz force.

Core claim

In the symmetric gauge, non-Hermitian Landau levels exhibit discretely spaced, highly degenerate complex spectra and biorthogonal eigenstates. Non-unitary gauge transformations play a clarified role. The continuum theory is confirmed by a non-Hermitian Harper-Hofstadter lattice model, which also reveals Gaussian wave packet dynamics governed by semiclassical equations with a complex Lorentz force.

What carries the argument

Non-Hermitian Landau levels formulated in the symmetric gauge under a complex perpendicular magnetic field, together with their biorthogonal eigenstates and the associated non-unitary gauge transformations.

If this is right

  • The spectra remain discretely spaced and highly degenerate even though the energies are complex.
  • Biorthogonal eigenstates replace ordinary orthonormal ones as the natural basis.
  • Gaussian wave packets obey semiclassical dynamics that include a complex Lorentz force.
  • Lattice realizations can serve as platforms for studying these levels.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The complex Lorentz force may produce wave-packet trajectories qualitatively different from those in the Hermitian case.
  • Engineered complex magnetic fields in optical or cold-atom lattices could provide an experimental route to these levels.
  • The formulation may extend to other gauge choices or to systems with additional non-Hermitian terms.

Load-bearing premise

A complex perpendicular magnetic field can be introduced consistently into the non-Hermitian Schrödinger equation while preserving the discrete, degenerate structure of the spectrum.

What would settle it

Numerical diagonalization of the non-Hermitian Harper-Hofstadter lattice model that fails to produce a discretely spaced complex spectrum matching the continuum prediction would falsify the central claim.

Figures

Figures reproduced from arXiv: 2605.23613 by Anton Montag, Tomoki Ozawa.

Figure 1
Figure 1. Figure 1: Eigenvalues and right eigenstates of the non-Hermitian Harper-Hofstadter model on a [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Trajectories of the center of mass of Gaussian wave [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Effective mass meff depending on wave packet width for a 50 × 50 square lattice for vanishing magnetic field. SM2: DISCUSSION OF WIDTH DEPENDENT EFFECTIVE MASS OF WAVE PACKET As mentioned in the letter, the effective mass of the wave packet meff depends in general on the width of the wave packet σ and for finite Im(B) it is also (weakly) position dependent. In the parameter regime used for the simulation t… view at source ↗
read the original abstract

We formulate non-Hermitian Landau levels in two-dimensional systems under a complex perpendicular magnetic field. In the symmetric gauge, we derive their discretely spaced, highly degenerate complex spectra and biorthogonal eigenstates, and clarify the role of non-unitary gauge transformations. A non-Hermitian Harper-Hofstadter lattice model confirms the continuum theory and reveals Gaussian wave packet dynamics governed by semiclassical equations with a complex Lorentz force, pointing to possible experimental realizations of complex magnetic fields.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript formulates non-Hermitian Landau levels for two-dimensional systems subject to a complex perpendicular magnetic field. In the symmetric gauge it derives discretely spaced, highly degenerate complex spectra together with their biorthogonal eigenstates, clarifies the role of non-unitary gauge transformations, and confirms the continuum results via a non-Hermitian Harper-Hofstadter lattice model that additionally exhibits Gaussian wave-packet dynamics governed by semiclassical equations containing a complex Lorentz force.

Significance. If the central construction is valid, the work supplies a concrete analytic framework for Landau-level physics in non-Hermitian settings and identifies a lattice realization that could be engineered experimentally. The explicit treatment of biorthogonal states and the complex Lorentz force constitute concrete, falsifiable predictions that go beyond abstract non-Hermitian extensions.

major comments (2)
  1. [Derivation of the continuum spectrum (symmetric-gauge section)] The central claim that the spectrum remains discretely spaced and exactly degenerate for arbitrary complex B rests on the continued validity of the ladder-operator algebra. The manuscript must supply an explicit verification (e.g., the commutator [a, a†] and the action of a† on the nth level) that this algebra closes without correction terms once Im(B) is nonzero; any deviation immediately lifts the degeneracy of higher levels.
  2. [Biorthogonal eigenstates and gauge transformations] Normalizability of the biorthogonal ground state (and hence of all higher states) for arbitrary complex B is asserted but not demonstrated. The Gaussian factor must be shown to remain square-integrable in the biorthogonal inner product when the imaginary part of the cyclotron frequency is present; otherwise the discrete spectrum is lost.
minor comments (2)
  1. [Abstract] The abstract states that derivations exist but supplies no equations; the main text should include at least the key commutator and the explicit form of the complex-frequency operators in the first derivation section.
  2. [Lattice-model section] The lattice-model confirmation is described only qualitatively; a quantitative comparison (e.g., energy-level spacing versus continuum prediction for several values of complex flux) would strengthen the claim.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful reading and constructive major comments. We address each point below and will revise the manuscript accordingly to include the requested explicit verifications.

read point-by-point responses
  1. Referee: [Derivation of the continuum spectrum (symmetric-gauge section)] The central claim that the spectrum remains discretely spaced and exactly degenerate for arbitrary complex B rests on the continued validity of the ladder-operator algebra. The manuscript must supply an explicit verification (e.g., the commutator [a, a†] and the action of a† on the nth level) that this algebra closes without correction terms once Im(B) is nonzero; any deviation immediately lifts the degeneracy of higher levels.

    Authors: We agree that an explicit verification of the ladder-operator algebra for complex B strengthens the presentation. The kinetic momenta satisfy [π_x, π_y] = −i ħ e B with B complex; the ladder operators a and a† are then defined in the usual manner (normalized by the appropriate factor involving |B| or the real part as needed), yielding [a, a†] = 1 with no correction terms generated by Im(B). The action a† |n⟩ = √(n+1) |n+1⟩ likewise holds identically. To address the request directly we will insert a short dedicated paragraph in the symmetric-gauge section that computes the commutator and the raising/lowering actions explicitly for general complex B. revision: yes

  2. Referee: [Biorthogonal eigenstates and gauge transformations] Normalizability of the biorthogonal ground state (and hence of all higher states) for arbitrary complex B is asserted but not demonstrated. The Gaussian factor must be shown to remain square-integrable in the biorthogonal inner product when the imaginary part of the cyclotron frequency is present; otherwise the discrete spectrum is lost.

    Authors: We acknowledge that an explicit demonstration of normalizability in the biorthogonal inner product was omitted. The right eigenfunctions contain a Gaussian factor whose exponent involves the complex cyclotron frequency ω_c = eB/m; the corresponding left eigenfunctions involve the adjoint form. Their biorthogonal product produces an integrand whose real part is controlled by Re(B) (or Re(ω_c)), ensuring exponential decay and finite norm provided Re(B) > 0. We will add this calculation, including the explicit evaluation of the ground-state norm for general complex B, to the revised manuscript. revision: yes

Circularity Check

0 steps flagged

No circularity: derivation extends standard Landau-level algebra to complex B without reduction to inputs or self-citations

full rationale

The paper begins from the non-Hermitian Schrödinger equation with a complex perpendicular magnetic field inserted into the symmetric-gauge vector potential. It constructs kinetic momenta whose commutator is proportional to the complex B, defines corresponding creation/annihilation operators, and obtains the spectrum and biorthogonal states by the usual algebraic procedure. No equations are shown that define a quantity in terms of itself, rename a fit as a prediction, or rely on a load-bearing self-citation whose content is unverified. The derivation is therefore self-contained against the stated Hamiltonian and does not reduce to its inputs by construction.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review supplies no explicit free parameters, axioms, or invented entities; ledger left empty.

pith-pipeline@v0.9.0 · 5592 in / 1051 out tokens · 18532 ms · 2026-05-25T04:20:56.574410+00:00 · methodology

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Works this paper leans on

61 extracted references · 61 canonical work pages · 1 internal anchor

  1. [1]

    L. D. Landau and E. M. Lifshitz,Quantum mechanics: non-relativistic theory, Vol. 3 (Elsevier, Oxford, 2013)

  2. [2]

    N. W. Ashcroft and N. D. Mermin,Solid state physics (Saunders College Publishing, New York, 1976)

  3. [3]

    K. v. Klitzing, G. Dorda, and M. Pepper, New method forhigh-accuracydeterminationofthefine-structurecon- stant based on quantized hall resistance, Phys. Rev. Lett. 45, 494 (1980)

  4. [4]

    D. C. Tsui, H. L. Stormer, and A. C. Gossard, Two- dimensional magnetotransport in the extreme quantum limit, Phys. Rev. Lett.48, 1559 (1982)

  5. [5]

    D. J. Thouless, M. Kohmoto, M. P. Nightingale, and M. den Nijs, Quantized hall conductance in a two- dimensional periodic potential, Phys. Rev. Lett.49, 405 (1982)

  6. [6]

    C. M. Bender, Making sense of non-hermitian hamiltoni- ans, Reports on Progress in Physics70, 947 (2007)

  7. [7]

    Rotter, A non-hermitian hamilton operator and the physics of open quantum systems, Journal of Physics A: Mathematical and Theoretical42, 153001 (2009)

    I. Rotter, A non-hermitian hamilton operator and the physics of open quantum systems, Journal of Physics A: Mathematical and Theoretical42, 153001 (2009)

  8. [8]

    Ashida, Z

    Y. Ashida, Z. Gong, and M. Ueda, Non-hermitian physics, Advances in Physics69, 249 (2020)

  9. [9]

    E. J. Bergholtz, J. C. Budich, and F. K. Kunst, Ex- ceptional topology of non-hermitian systems, Rev. Mod. Phys.93, 015005 (2021)

  10. [10]

    D. Zou, T. Chen, W. He, J. Bao, C. H. Lee, H. Sun, and X. Zhang, Observation of hybrid higher-order skin- topological effect in non-hermitian topolectrical circuits, Nature Communications12, 7201 (2021)

  11. [11]

    L. S. Palacios, S. Tchoumakov, M. Guix, I. Pagonabar- raga, S. Sánchez, and A. G. Grushin, Guided accu- mulation of active particles by topological design of a second-order skin effect, Nature Communications12, 4691 (2021)

  12. [12]

    Shang, S

    C. Shang, S. Liu, R. Shao, P. Han, X. Zang, X. Zhang, K. N. Salama, W. Gao, C. H. Lee, R. Thomale,et al., Experimental identification of the second-order non- hermitian skin effect with physics-graph-informed ma- chine learning, Advanced Science9, 2202922 (2022)

  13. [13]

    Yokomizo, T

    K. Yokomizo, T. Yoda, and S. Murakami, Non-hermitian waves in a continuous periodic model and application to photonic crystals, Phys. Rev. Res.4, 023089 (2022)

  14. [14]

    Non-Hermitian Topological Theory of Finite-Lifetime Quasiparticles: Prediction of Bulk Fermi Arc Due to Exceptional Point

    V. Kozii and L. Fu, Non-hermitian topological the- ory of finite-lifetime quasiparticles: prediction of bulk fermi arc due to exceptional point, arXiv preprint arXiv:1708.05841 (2017)

  15. [15]

    Z. Gong, Y. Ashida, K. Kawabata, K. Takasan, S. Hi- gashikawa, and M. Ueda, Topological phases of non- hermitian systems, Phys. Rev. X8, 031079 (2018)

  16. [16]

    Kawabata, K

    K. Kawabata, K. Shiozaki, M. Ueda, and M. Sato, Sym- metry and topology in non-hermitian physics, Phys. Rev. X9, 041015 (2019)

  17. [17]

    Okuma and M

    N. Okuma and M. Sato, Non-hermitian topological phe- nomena: A review, Annual Review of Condensed Matter Physics14, 83 (2023)

  18. [18]

    Shen and L

    H. Shen and L. Fu, Quantum oscillation from in-gap states and a non-hermitian landau level problem, Phys. Rev. Lett.121, 026403 (2018)

  19. [19]

    Zhang, C

    X. Zhang, C. Wu, M. Yan, N. Liu, Z. Wang, and G.Chen,Observationofcontinuumlandaumodesinnon- hermitian electric circuits, Nature Communications15, 1798 (2024)

  20. [20]

    J. Kim, B. Kim, B. Kim, H. Jeon, and S.-K. Kim, 6 Magnetic-fieldcontrolledon-offswitchablenon-reciprocal negative refractive index in non-hermitian photon- magnon hybrid systems, Nature Communications15, 9014 (2024)

  21. [21]

    H. T. Teo, S. Mandal, Y. Long, H. Xue, and B. Zhang, Pseudomagnetic suppression of non-hermitian skin effect, Science Bulletin69, 1667 (2024)

  22. [22]

    C. Wu, X. Zhang, J. Kang, Z. Cui, M. Yan, and G. Chen, Observation of non-hermiticity-induced unpolarized lan- dau levels in honeycomb circuit networks, Phys. Rev. B 112, 224302 (2025)

  23. [23]

    Longhi, Magnetic control of the non-hermitian skin effect in two-dimensional lattices, Phys

    S. Longhi, Magnetic control of the non-hermitian skin effect in two-dimensional lattices, Phys. Rev. B112, 214208 (2025)

  24. [24]

    Non-hermitian reshaping of high-order landau modes, Science Bulletin71, 1949 (2026)

  25. [25]

    B. Alon, M. Goldstein, and R. Ilan, Non-hermitian mag- netic moment, Phys. Rev. B113, L161118 (2026)

  26. [26]

    I. L. Paiva, Y. Aharonov, J. Tollaksen, and M. Waegell, Aharonov–bohm effect with an effective complex-valued vector potential, New Journal of Physics25, 053017 (2023)

  27. [27]

    Ozawa and T

    T. Ozawa and T. Hayata, Two-dimensional lattice with an imaginary magnetic field, Phys. Rev. B109, 085113 (2024)

  28. [28]

    Medina-Guerra, I

    E. Medina-Guerra, I. V. Gornyi, and Y. Gefen, Correla- tions and krylov spread for a non-hermitian hamiltonian: Ising chain with a complex-valued transverse magnetic field, Phys. Rev. B111, 174207 (2025)

  29. [29]

    Hatano and D

    N. Hatano and D. R. Nelson, Localization transitions in non-hermitian quantum mechanics, Phys. Rev. Lett.77, 570 (1996)

  30. [30]

    Hatano and D

    N. Hatano and D. R. Nelson, Vortex pinning and non- hermitian quantum mechanics, Phys. Rev. B56, 8651 (1997)

  31. [31]

    Yao and Z

    S. Yao and Z. Wang, Edge states and topological in- variants of non-hermitian systems, Phys. Rev. Lett.121, 086803 (2018)

  32. [32]

    Brandenbourger, X

    M. Brandenbourger, X. Locsin, E. Lerner, and C.Coulais,Non-reciprocalroboticmetamaterials,Nature communications10, 4608 (2019)

  33. [33]

    D. S. Borgnia, A. J. Kruchkov, and R.-J. Slager, Non- hermitian boundary modes and topology, Phys. Rev. Lett.124, 056802 (2020)

  34. [34]

    Okuma, K

    N. Okuma, K. Kawabata, K. Shiozaki, and M. Sato, Topological origin of non-hermitian skin effects, Phys. Rev. Lett.124, 086801 (2020)

  35. [35]

    Ghatak, M

    A. Ghatak, M. Brandenbourger, J. van Wezel, and C. Coulais, Observation of non-hermitian topology and its bulk–edge correspondence in an active mechanical metamaterial, Proceedings of the National Academy of Sciences117, 29561 (2020)

  36. [36]

    Helbig, T

    T. Helbig, T. Hofmann, S. Imhof, M. Abdelghany, T. Kiessling, L. W. Molenkamp, C. H. Lee, A. Szameit, M. Greiter, and R. Thomale, Generalized bulk–boundary correspondence in non-hermitian topolectrical circuits, Nature Physics16, 747 (2020)

  37. [37]

    Weidemann, M

    S. Weidemann, M. Kremer, T. Helbig, T. Hofmann, A. Stegmaier, M. Greiter, R. Thomale, and A. Szameit, Topological funneling of light, Science368, 311 (2020)

  38. [38]

    Hofmann, T

    T. Hofmann, T. Helbig, F. Schindler, N. Salgo, M. Brzez- ińska, M. Greiter, T. Kiessling, D. Wolf, A. Vollhardt, A. Kabaši, C. H. Lee, A. Bilušić, R. Thomale, and T. Neupert, Reciprocal skin effect and its realization in a topolectrical circuit, Phys. Rev. Res.2, 023265 (2020)

  39. [39]

    L. Xiao, T. Deng, K. Wang, G. Zhu, Z. Wang, W. Yi, and P. Xue, Non-hermitian bulk–boundary correspondence in quantum dynamics, Nature Physics16, 761 (2020)

  40. [40]

    L. Xiao, T. Deng, K. Wang, Z. Wang, W. Yi, and P. Xue, Observation of non-bloch parity-time symmetry and ex- ceptional points, Phys. Rev. Lett.126, 230402 (2021)

  41. [41]

    Liang, D

    Q. Liang, D. Xie, Z. Dong, H. Li, H. Li, B. Gadway, W. Yi, and B. Yan, Dynamic signatures of non-hermitian skin effect and topology in ultracold atoms, Phys. Rev. Lett.129, 070401 (2022)

  42. [42]

    R. Lin, T. Tai, L. Li, and C. H. Lee, Topological non- hermitian skin effect, Frontiers of Physics18, 53605 (2023)

  43. [43]

    Zhong, K

    J. Zhong, K. Wang, Y. Park, V. Asadchy, C. C. Wojcik, A. Dutt, and S. Fan, Nontrivial point-gap topology and non-hermitian skin effect in photonic crystals, Phys. Rev. B104, 125416 (2021)

  44. [44]

    D. C. Brody, Biorthogonal quantum mechanics, Journal of Physics A: Mathematical and Theoretical47, 035305 (2013)

  45. [45]

    F. K. Kunst, E. Edvardsson, J. C. Budich, and E. J. Bergholtz, Biorthogonal bulk-boundary correspondence in non-hermitian systems, Phys. Rev. Lett.121, 026808 (2018)

  46. [46]

    L. D. Landau and E. M. Lifshitz,Mechanics and electro- dynamics(Elsevier, Oxford, 2013)

  47. [47]

    P. G. Harper, Single band motion of conduction electrons in a uniform magnetic field, Proceedings of the Physical Society. Section A68, 874 (1955)

  48. [48]

    D. R. Hofstadter, Energy levels and wave functions of bloch electrons in rational and irrational magnetic fields, Phys. Rev. B14, 2239 (1976)

  49. [49]

    See Supplemental Material at [URL will be inserted by publisher] for solution of the semi-classical equations of motion for complex-valued amagnetic fields

  50. [50]

    S. M. Rafi-Ul-Islam, Z. B. Siu, and M. B. A. Jalil, Non- hermitian topological phases and exceptional lines in topolectrical circuits, New Journal of Physics23, 033014 (2021)

  51. [51]

    Ş. K. Özdemir, S. Rotter, F. Nori, and L. Yang, Parity– time symmetry and exceptional points in photonics, Na- ture materials18, 783 (2019)

  52. [52]

    Liu, Z.-w

    J.-j. Liu, Z.-w. Li, Z.-G. Chen, W. Tang, A. Chen, B. Liang, G. Ma, and J.-C. Cheng, Experimental real- ization of weyl exceptional rings in a synthetic three- dimensional non-hermitian phononic crystal, Phys. Rev. Lett.129, 084301 (2022)

  53. [53]

    Opala, M

    A. Opala, M. Furman, M. Król, R. Mirek, K. Tyszka, B. Seredyński, W. Pacuski, J. Szczytko, M. Matuszewski, and B. Piętka, Natural exceptional points in the excita- tion spectrum of a light–matter system, Optica10, 1111 (2023)

  54. [54]

    M. V. Berry, Quantal phase factors accompanying adia- batic changes, Proceedings of the Royal Society of Lon- don. A. Mathematical and Physical Sciences392, 45 (1984)

  55. [55]

    Dalibard, F

    J. Dalibard, F. Gerbier, G. Juzeli¯ unas, and P. Öh- berg, Colloquium: Artificial gauge potentials for neutral atoms, Rev. Mod. Phys.83, 1523 (2011)

  56. [56]

    Y.-J. Lin, R. L. Compton, A. R. Perry, W. D. Phillips, J. V. Porto, and I. B. Spielman, Bose-einstein condensate in a uniform light-induced vector potential, Phys. Rev. Lett.102, 130401 (2009). 7

  57. [57]

    Y.-J. Lin, R. L. Compton, K. Jiménez-García, J. V. Porto, and I. B. Spielman, Synthetic magnetic fields for ultracold neutral atoms, Nature462, 628 (2009)

  58. [58]

    A.MontagandT.Ozawa,Quantumgeometricaleffectsin non-hermitiansystems,Phys.Rev.Res.8,013181(2026)

  59. [59]

    J. E. Avron, I. W. Herbst, and B. Simon, Schrödinger op- erators with magnetic fields. i. general interactions, Duke Mathematical Journal45, 847 (1978)

  60. [60]

    Tsuru, Wave packet motion in magnetic field, Journal of the Physical Society of Japan61, 2246 (1992)

    H. Tsuru, Wave packet motion in magnetic field, Journal of the Physical Society of Japan61, 2246 (1992)

  61. [61]

    Ozawa and I

    T. Ozawa and I. Carusotto, Synthetic dimensions with magnetic fields and local interactions in photonic lattices, Phys. Rev. Lett.118, 013601 (2017). 8 Supplemental Material: Non-Hermitian Landau Levels SM1: SPECIAL SOLUTIONS OF THE SEMICLASSICAL EQUATIONS OF MOTION FOR THE COMPLEX-VALUED LORENTZ FORCE Here we present the solutions of the semiclassical eq...