Geometry-Controlled Exceptional Points in Helicoidal Orbital-Angular-Momentum Photonics

• URL: http://arxiv.org/abs/2606.22240v1
• Date: Sat, 20 Jun 2026 21:53:12 GMT
• Title: Geometry-Controlled Exceptional Points in Helicoidal Orbital-Angular-Momentum Photonics
• Abstract summary: Exceptional points (EPs) are non-Hermitian spectral singularities where eigenvalues and eigenvectors coalesce.<n>We propose a geometry-controlled route to EPs in orbital-angular-momentum (OAM) photonics.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Exceptional points (EPs) are non-Hermitian spectral singularities where eigenvalues and eigenvectors coalesce. We propose a geometry-controlled route to EPs in orbital-angular-momentum (OAM) photonics. In an effective torsion-free helicoidal background, the twist supplies a signed, real chiral splitting between opposite-OAM modes, while openness, gain, loss, leakage, or channel coupling, supplies the non-Hermiticity. The EP is reached when the geometric detuning compensates for a residual mode splitting and the linewidth contrast meets the non-Hermitian balance condition; the twist rate is thus the control parameter, not the source of non-Hermiticity. We obtain the OAM slope both for a confined quantum problem and, in the paraxial regime, for a helically twisted guide, and embed the OAM doublet in a multimode mode-space model to show that the EP survives spectator modes. Eigenvalue coalescence, phase-rigidity collapse, linear EP tracking with residual detuning, and branch exchange under geometric encircling provide falsifiable signatures. An OAM-resolved input-output response maps these onto spectroscopy-level observables, including spectral maps and three-dimensional Riemann-surface visualizations. A device-level paraxial simulation of two distinct photonic platforms, one reciprocal and one asymmetric-coupling Wiersig-type platform, reproduces the predicted exceptional point and its linear geometric tracking.

Related papers

• A Gauge-Covariant Geometric Framework for Non-Hermitian Quantum Systems [0.0]
  We develop a comprehensive, gauge-covariant geometric framework for non-Hermitian quantum systems.<n>We show that the non-Hermitian geometric curvature originates from the non-commutativity of the stretching components at the operator level.<n>We also examine physical realizations of this model, including the non-Hermitian Su--Schrieffer--Heeger (SSH) and Hatano--Nelson (HN)
  arXiv  Detail & Related papers  (2026-06-14T16:58:04Z)
• Programmable spectral symmetries in an anisotropic quantum Rabi simulator [23.8573887639585]
  We realize a programmable anisotropic quantum Rabi model in a superconducting processor.<n>We show that anisotropy reconstructs the spectrum and turns complete collapse-revival dynamics into incomplete revivals even near degeneracy.
  arXiv  Detail & Related papers  (2026-06-03T17:08:27Z)
• Multiple Bulk-Boundary Correspondences and Anomalous Modes in a Non-Hermitian Creutz Ladder [6.984646820509479]
  We study a non-Hermitian Creutz ladder that incorporates both gain-loss and nonreciprocity.<n>We construct multiple BBCs involving scale-free, normal and anomalous skin modes, as well as topological zero-energy modes.
  arXiv  Detail & Related papers  (2026-05-01T11:48:57Z)
• Symmetry-protected topology and deconfined solitons in a multi-link $\mathbb{Z}_2$ gauge theory [45.88028371034407]
  We study a $mathbbZ$ lattice gauge theory defined on a multi-graph with links that can be visualized as great circles of a spherical shell.<n>We show that this leads to state-dependent tunneling amplitudes underlying a phenomenon analogous to the Peierls instability.<n>By performining a detailed analysis based on matrix product states, we prove that charge deconfinement emerges as a consequence of charge-fractionalization.
  arXiv  Detail & Related papers  (2026-03-02T22:59:25Z)
• Unveiling the Self-Orthogonality at Exceptional Points in Driven $\mathcal{PT}$-Symmetric Systems [79.16635054977068]
  We explore the effect of self-orthogonality at exceptional points (EPs) in non-Hermitian Parity-Time-symmetric systems.<n>Using a driven three-band lattice model, we show that the Rabi frequency diverges as the system approaches an EP due to the coalescence of eigenstates.
  arXiv  Detail & Related papers  (2025-07-14T12:53:10Z)
• Controlling Excitation Localization in Waveguide QED Systems [0.4999814847776098]
  We study localization and long-time population trapping in quantum emitters coupled to a waveguide.<n>We find two distinct mechanisms that give rise to localization: geometry-induced subradiance and disorder-induced Anderson-like confinement.<n>These results establish geometry and disorder as complementary tools for engineering long-lived quantum states in waveguide QED systems.
  arXiv  Detail & Related papers  (2025-05-27T08:24:51Z)
• Effects of detuning on $\mathcal{PT}$-symmetric, tridiagonal, tight-binding models [0.0]
  Non-Hermitian, tight-binding $mathcalPT$-symmetric models are extensively studied in the literature. Here, we investigate two forms of non-Hermitian Hamiltonians to study the $mathcalPT$-symmetry breaking thresholds and features of corresponding surfaces of exceptional points (EPs) Taken together, our results provide a detailed understanding of detuned tight-binding models with a pair of gain-loss potentials.
  arXiv  Detail & Related papers  (2023-02-26T01:36:59Z)
• Regression of high dimensional angular momentum states of light [47.187609203210705]
  We present an approach to reconstruct input OAM states from measurements of the spatial intensity distributions they produce. We showcase our approach in a real photonic setup, generating up-to-four-dimensional OAM states through a quantum walk dynamics.
  arXiv  Detail & Related papers  (2022-06-20T16:16:48Z)
• Noise-resilient Edge Modes on a Chain of Superconducting Qubits [103.93329374521808]
  Inherent symmetry of a quantum system may protect its otherwise fragile states. We implement the one-dimensional kicked Ising model which exhibits non-local Majorana edge modes (MEMs) with $mathbbZ$ parity symmetry. MEMs are found to be resilient against certain symmetry-breaking noise owing to a prethermalization mechanism.
  arXiv  Detail & Related papers  (2022-04-24T22:34:15Z)
• Geometric phase in a dissipative Jaynes-Cummings model: theoretical explanation for resonance robustness [68.8204255655161]
  We compute the geometric phases acquired in both unitary and dissipative Jaynes-Cummings models. In the dissipative model, the non-unitary effects arise from the outflow of photons through the cavity walls. We show the geometric phase is robust, exhibiting a vanishing correction under a non-unitary evolution.
  arXiv  Detail & Related papers  (2021-10-27T15:27:54Z)
• Observation of Hermitian and Non-Hermitian Diabolic Points and Exceptional Rings in Parity-Time symmetric ZRC and RLC Dimers [62.997667081978825]
  We show how appears non-Hermitian degeneracy points in the spectrum and how they are protected against a Hermitian perturbation. This work opens a gold road for investigations on topological electrical circuits for robust transport of information at room temperature.
  arXiv  Detail & Related papers  (2020-04-17T15:51:49Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.