The reviewed record of science sign in
Pith

arxiv: 2606.19786 · v1 · pith:RIHFP5V5 · submitted 2026-06-18 · quant-ph

Robust Generation of Topological Biphoton Mode via Adiabatic Passage

Jaesung Lim , Jihwan Kim , Dong-Gil Im , Kyungdeuk Park , Dongkyu Kim , Yonggi Jo , Yong Sup Ihn This is my paper

Reviewed by Pith T0 review T1 audit T2 compute T3 formal T4 kernel 2026-06-26 17:36 UTCgrok-4.3pith:RIHFP5V5record.jsonopen to challenge →

classification quant-ph
keywords topological biphotonadiabatic passagewaveguide disorderSchmidt numberNOON statesquantum photonicsnonlinear generationtopological arrays
0
0 comments X

The pith

Adiabatic passage from isolated site to topological defect array generates biphoton modes that keep unit Schmidt number and high fidelity under waveguide gap disorder.

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

The paper establishes that standard topological waveguide arrays lose robustness during nonlinear biphoton generation because structural disorder excites non-topological modes and degrades the quantum state. It proposes an adiabatic passage that begins the nonlinear process at a strongly isolated site and then smoothly connects the generated state into a topological defect array. Starting in isolation suppresses unwanted nonlinear couplings, after which the adiabatic transfer moves the biphoton into the protected mode with high fidelity. Numerical simulations show this scheme preserves both high fidelity and a unit Schmidt number even when waveguide gaps vary, and the same protection holds for path-entangled NOON states with near-unity visibility.

Core claim

By initiating the nonlinear process in a strongly isolated regime and using adiabatic passage to connect to a topological defect array, the scheme suppresses nonlinear coupling to unwanted modes and facilitates high-fidelity transfer of the generated biphoton into the topological mode, thereby maintaining a unit Schmidt number in the presence of waveguide gap disorder.

What carries the argument

adiabatic passage connecting an isolated site to a topological defect array

If this is right

  • High biphoton fidelity is maintained in the presence of waveguide gap disorder.
  • A unit Schmidt number is preserved for the generated state.
  • Robustness extends to path-entangled NOON states, yielding near-unity quantum interference visibility.
  • The approach supplies a design strategy for disorder-tolerant integrated quantum photonic devices.

Where Pith is reading between the lines

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

  • The scheme could lessen sensitivity to fabrication variations in on-chip quantum light sources.
  • Adiabatic isolation techniques might extend to other nonlinear topological processes such as multi-photon entanglement generation.
  • Direct comparison experiments on the same chip with and without the isolated starting site would isolate the contribution of the adiabatic step.

Load-bearing premise

The nonlinear process can be initiated in a strongly isolated regime to suppress nonlinear coupling to unwanted modes.

What would settle it

Fabricate the adiabatic waveguide structure with controlled gap disorder and measure the Schmidt number of the output biphoton state to check whether it remains unity while a conventional topological array does not.

Figures

Figures reproduced from arXiv: 2606.19786 by Dong-Gil Im, Dongkyu Kim, Jaesung Lim, Jihwan Kim, Kyungdeuk Park, Yonggi Jo, Yong Sup Ihn.

Figure 1
Figure 1. Figure 1: FIG. 1. Concept of topological biphoton generation via adi [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Adiabatic evolution of the pump and biphoton states for a device length of 1 [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. Comparison of the gap disorder tolerance between an adiabatic structure and a conventional topological waveguide [PITH_FULL_IMAGE:figures/full_fig_p005_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4. Adiabatic scheme for a trivial defect case. (a) Cross section of the trivial defect array (top) and the intensity profile of [PITH_FULL_IMAGE:figures/full_fig_p006_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5. Robustness of path entangled topological biphoton [PITH_FULL_IMAGE:figures/full_fig_p007_5.png] view at source ↗
read the original abstract

Topological waveguide arrays support robust mode propagation in the presence of fabrication imperfections, providing a significant advantage for on-chip quantum information processing. However, this robustness does not fully extend to nonlinear biphoton generation. Structural disorder can enhance the excitation of non-topological biphoton modes during nonlinear interactions, which degrades the quantum properties of the generated state. To overcome this limitation, we propose an adiabatic passage that connects an isolated site to a topological defect array. By initiating the nonlinear process in a strongly isolated regime, nonlinear coupling to unwanted modes is effectively suppressed, thereby preserving the Schmidt number of the generated state. The subsequent adiabatic connection facilitates the high fidelity transfer of the generated biphoton into the topological biphoton mode. Our numerical simulations demonstrate that, unlike conventional topological structures, the adiabatic scheme maintains both high biphoton fidelity and a unit Schmidt number in the presence of waveguide gap disorder. Furthermore, we show that this robustness extends to path entangled NOON states, achieving a near-unity quantum interference visibility. Our approach provides a practical design strategy for disorder-tolerant integrated quantum photonic devices.

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 proposes an adiabatic passage scheme connecting an isolated waveguide site to a topological defect array for generating biphoton states. It claims that starting the nonlinear process in a strongly isolated regime suppresses coupling to non-topological modes, after which the adiabatic ramp transfers the state into a topological biphoton mode while preserving high fidelity and unit Schmidt number under waveguide gap disorder—unlike conventional topological structures. Numerical simulations are said to demonstrate this robustness, which is further claimed to extend to path-entangled NOON states with near-unity interference visibility.

Significance. If the numerical evidence holds after clarification of modeling choices, the work would provide a concrete design strategy for disorder-tolerant nonlinear quantum photonic sources on chip, extending topological protection into the generation stage where it has previously been limited. The approach is parameter-light in its conceptual framing and directly addresses a practical fabrication challenge in integrated quantum optics.

major comments (2)
  1. [Abstract / numerical results section] Abstract and simulation description: the central robustness claim (high biphoton fidelity and unit Schmidt number under gap disorder) rests entirely on numerical simulations, yet no parameters (propagation length, nonlinearity strength, disorder amplitude distribution, number of realizations), disorder model (e.g., whether gap disorder is applied uniformly including to the initial isolated site at t=0), or quantitative metrics (fidelity vs. disorder strength with error bars or failure rates) are supplied. This absence makes the evidential support for the strongest claim moderate at best.
  2. [Proposal for adiabatic connection scheme] The modeling choice that the initial isolated regime remains strongly isolated (suppressing unwanted-mode coupling before the ramp) appears to assume a disorder-free launch site. If gap disorder is present from t=0 on the initial waveguide, the isolation condition itself is perturbed; the manuscript should explicitly state whether the initial site is exempted from disorder or how the adiabatic connection remains robust when the starting point is already disordered. This assumption is load-bearing for the claimed advantage over conventional structures.
minor comments (2)
  1. Notation for the Schmidt number and fidelity should be defined at first use with explicit formulas or references to standard definitions in the biphoton literature.
  2. Figure captions for the simulation results should include the precise disorder model and parameter values used in each panel.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful and constructive review. The comments highlight important aspects of the numerical evidence and modeling assumptions that require clarification. We address each major comment below and have revised the manuscript to provide the requested details and explicit statements.

read point-by-point responses

  1. Referee: [Abstract / numerical results section] Abstract and simulation description: the central robustness claim (high biphoton fidelity and unit Schmidt number under gap disorder) rests entirely on numerical simulations, yet no parameters (propagation length, nonlinearity strength, disorder amplitude distribution, number of realizations), disorder model (e.g., whether gap disorder is applied uniformly including to the initial isolated site at t=0), or quantitative metrics (fidelity vs. disorder strength with error bars or failure rates) are supplied. This absence makes the evidential support for the strongest claim moderate at best.

    Authors: We agree that the presentation of the numerical results in the abstract and main text would benefit from additional quantitative detail. In the revised manuscript we have expanded the simulation description to include the propagation length, nonlinearity strength, the uniform distribution used for gap disorder amplitudes, the number of realizations (1000), and plots of fidelity versus disorder strength with error bars together with failure rates. The disorder model is now stated explicitly as applying uniformly to all waveguides, including the initial isolated site at t=0. revision: yes

  2. Referee: [Proposal for adiabatic connection scheme] The modeling choice that the initial isolated regime remains strongly isolated (suppressing unwanted-mode coupling before the ramp) appears to assume a disorder-free launch site. If gap disorder is present from t=0 on the initial waveguide, the isolation condition itself is perturbed; the manuscript should explicitly state whether the initial site is exempted from disorder or how the adiabatic connection remains robust when the starting point is already disordered. This assumption is load-bearing for the claimed advantage over conventional structures.

    Authors: We acknowledge that the original text did not explicitly address whether the initial site experiences the same gap disorder. In the revised manuscript we state that the initial site is subject to the identical disorder model from t=0 and we include additional numerical results demonstrating that the isolation remains sufficient to suppress coupling to non-topological modes prior to the adiabatic ramp, thereby preserving the reported robustness advantage. revision: yes

Circularity Check

0 steps flagged

No significant circularity; results are simulation outcomes on an independent physical model

full rationale

The paper proposes an adiabatic connection scheme from an isolated site to a topological defect array and reports numerical simulation results showing preserved fidelity and unit Schmidt number under gap disorder. These outcomes are generated by applying the proposed dynamics to the model equations rather than being forced by definition, fitted parameters renamed as predictions, or self-citation chains. The isolated-regime initiation is an explicit modeling assumption whose validity can be checked externally; it does not render the reported robustness tautological. No load-bearing derivation step reduces to its own inputs by construction.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

Based on the abstract, the work relies on standard domain assumptions from quantum optics and topological photonics without introducing new free parameters or invented entities.

axioms (1)
  • domain assumption Standard coupled-mode theory and nonlinear interaction models apply to the waveguide arrays
    Implicit in the description of topological modes, disorder effects, and biphoton generation.

pith-pipeline@v0.9.1-grok · 5743 in / 1237 out tokens · 32559 ms · 2026-06-26T17:36:27.887718+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

38 extracted references

  1. [1]

    long-long

    A “long-long” defect is formed by placing long gaps on both sides of the central waveguide, producing a single central topological defect mode. The Hamiltonian of the topological lattice is constructed using nearest-neighbor coupling constants extracted from finite-element method (FEM) simulations and is given by HSSH = 119X i=0 ci (|i⟩ ⟨i+ 1|+|i+ 1⟩ ⟨i|)...

  2. [2]

    J. Wang, F. Sciarrino, A. Laing, and M. G. Thompson, Integrated photonic quantum technologies, Nature Pho- tonics14, 273 (2020)

    2020

  3. [3]

    Moody, V

    G. Moody, V. J. Sorger, D. J. Blumenthal, P. W. Juo- dawlkis, W. Loh, C. Sorace-Agaskar, A. E. Jones, K. C. Balram, J. C. Matthews, A. Laing,et al., 2022 roadmap on integrated quantum photonics, Journal of Physics: Photonics4, 012501 (2022)

    2022

  4. [4]

    W. Luo, L. Cao, Y. Shi, L. Wan, H. Zhang, S. Li, G. Chen, Y. Li, S. Li, Y. Wang,et al., Recent progress in quantum photonic chips for quantum communication and internet, Light: Science & Applications12, 175 (2023)

    2023

  5. [5]

    J. W. Silverstone, D. Bonneau, J. L. O’Brien, and M. G. Thompson, Silicon quantum photonics, IEEE Journal of Selected Topics in Quantum Electronics22, 390 (2016)

    2016

  6. [6]

    Sibson, C

    P. Sibson, C. Erven, M. Godfrey, S. Miki, T. Yamashita, M. Fujiwara, M. Sasaki, H. Terai, M. G. Tanner, C. M. Natarajan,et al., Chip-based quantum key distribution, Nature Communications8, 13984 (2017)

    2017

  7. [7]

    Zhang, J

    G. Zhang, J. Y. Haw, H. Cai, F. Xu, S. Assad, J. F. Fitzsimons, X. Zhou, Y. Zhang, S. Yu, J. Wu,et al., An integrated silicon photonic chip platform for continuous variable quantum key distribution, Nature Photonics13, 839 (2019)

    2019

  8. [8]

    Politi, J

    A. Politi, J. C. Matthews, and J. L. O’Brien, Shor’s quan- tum factoring algorithm on a photonic chip, Science325, 1221 (2009)

    2009

  9. [9]

    PsiQuantum Team, A manufacturable platform for pho- tonic quantum computing, Nature641, 876 (2025)

    2025

  10. [10]

    A. Dutt, A. Mohanty, A. L. Gaeta, and M. Lipson, Non- linear and quantum photonics using integrated optical materials, Nature Reviews Materials9, 321 (2024)

    2024

  11. [11]

    J. W. Silverstone, D. Bonneau, K. Ohira, N. Suzuki, H. Yoshida, N. Iizuka, M. Ezaki, C.M. Natarajan, M.G. Tanner, R.H. Hadfieldet al., On-chip quantum interfer- ence between silicon photon-pair sources, Nature Pho- tonics8, 104 (2014)

    2014

  12. [12]

    H. Jin, F. Liu, P. Xu, J. Xia, M. Zhong, Y. Yuan, J. Zhou, Y. Gong, W. Wang, and S. Zhu, On-chip gener- ation and manipulation of entangled photons based on reconfigurable lithium-niobate waveguide circuits, Phys- ical Review Letters113, 103601 (2014)

    2014

  13. [13]

    Setzpfandt, A

    F. Setzpfandt, A. S. Solntsev, J. Titchener, C. W. Wu, C. Xiong, R. Schiek, T. Pertsch, D. N. Neshev, and A. A. Sukhorukov, Tunable generation of entangled photons in a nonlinear directional coupler, Laser & Photonics Re- views10, 131 (2016)

    2016

  14. [14]

    A. S. Solntsev, A. A. Sukhorukov, D. N. Neshev, and Y. S. Kivshar, Spontaneous parametric down-conversion and quantum walks in arrays of quadratic nonlinear waveguides, Physical Review Letters108, 023601 (2012)

    2012

  15. [15]

    A. S. Solntsev, A. A. Sukhorukov, D. N. Neshev, and Y. S. Kivshar, Photon-pair generation in arrays of cubic nonlinear waveguides, Optics Express20, 27441 (2012)

    2012

  16. [16]

    A. S. Solntsev, F. Setzpfandt, A. S. Clark, C. W. Wu, M. J. Collins, C. Xiong, A. Schreiber, F. Katzschmann, F. Eilenberger, R. Schiek,et al., Generation of nonclassical biphoton states through cascaded quantum walks on a nonlinear chip, Physical Review X4, 031007 (2014)

    2014

  17. [17]

    L. Lu, J. D. Joannopoulos, and M. Soljaˇ ci´ c, Topological photonics, Nature Photonics8, 821 (2014)

    2014

  18. [18]

    Ozawa, H

    T. Ozawa, H. M. Price, A. Amo, N. Goldman, M. Hafezi, L. Lu, M. C. Rechtsman, D. Schuster, J. Simon, O. Zil- berberg,et al., Topological photonics, Reviews of Modern Physics91, 015006 (2019)

    2019

  19. [19]

    W.-P. Su, J. R. Schrieffer, and A. J. Heeger, Solitons in polyacetylene, Physical Review Letters42, 1698 (1979)

    1979

  20. [20]

    Zak, Berry’s phase for energy bands in solids, Physical Review Letters62, 2747 (1989)

    J. Zak, Berry’s phase for energy bands in solids, Physical Review Letters62, 2747 (1989)

    1989

  21. [21]

    J. K. Asb´ oth, L. Oroszl´ any, and A. P´ alyi,A short course on topological insulators, Vol.919 (Springer, 2016)

    2016

  22. [22]

    Cheng, Y

    Q. Cheng, Y. Pan, Q. Wang, T. Li, and S. Zhu, Topolog- ically protected interface mode in plasmonic waveguide arrays, Laser & Photonics Reviews9, 392 (2015)

    2015

  23. [23]

    Blanco-Redondo, I

    A. Blanco-Redondo, I. Andonegui, M. J. Collins, G. Harari, Y. Lumer, M. C. Rechtsman, B. J. Eggleton, and M. Segev, Topological optical waveguiding in silicon and the transition between topological and trivial defect 9 states, Physical Review Letters116, 163901 (2016)

    2016

  24. [24]

    W. Song, W. Sun, C. Chen, Q. Song, S. Xiao, S. Zhu, and T. Li, Robust and broadband optical coupling by topological waveguide arrays, Laser & Photonics Reviews 14, 1900193 (2020)

    2020

  25. [25]

    Q. Yan, X. Hu, Y. Fu, C. Lu, C. Fan, Q. Liu, X. Feng, Q. Sun, and Q. Gong, Quantum topological photonics, Advanced Optical Materials9, 2001739 (2021)

    2021

  26. [26]

    Smirnova, D

    D. Smirnova, D. Leykam, Y. Chong, and Y. Kivshar, Nonlinear topological photonics, Applied Physics Re- views7(2020)

    2020

  27. [27]

    Hashemi, M

    A. Hashemi, M. J. Zakeri, P. S. Jung, and A. Blanco- Redondo, Topological quantum photonics, APL Photon- ics10(2025)

    2025

  28. [28]

    Blanco-Redondo, B

    A. Blanco-Redondo, B. Bell, D. Oren, B. J. Eggleton, and M. Segev, Topological protection of biphoton states, Science362, 568 (2018)

    2018

  29. [29]

    M. Wang, C. Doyle, B. Bell, M. J. Collins, E. Magi, B. J. Eggleton, M. Segev, and A. Blanco-Redondo, Topologi- cally protected entangled photonic states, Nanophotonics 8, 1327 (2019)

    2019

  30. [30]

    Doyle, W.-W

    C. Doyle, W.-W. Zhang, M. Wang, B. A. Bell, S. D. Bartlett, and A. Blanco-Redondo, Biphoton entangle- ment of topologically distinct modes, Physical Review A105, 023513 (2022)

    2022

  31. [31]

    M. J. Zakeri, A. Perez-Leija, and A. Blanco-Redondo, High-dimensional topological photonic entanglement, Science391, 1379 (2026)

    2026

  32. [32]

    Bergamasco, J

    N. Bergamasco, J. Sipe, and M. Liscidini, Generation of hyper-entangled states in strongly coupled topological defects, Optics Letters46, 2244 (2021)

    2021

  33. [33]

    Bergamasco and M

    N. Bergamasco and M. Liscidini, Generation of photon pairs in topologically protected guided modes, Physical Review A100, 053827 (2019)

    2019

  34. [34]

    Longhi, Topological pumping of edge states via adia- batic passage, Physical Review B99, 155150 (2019)

    S. Longhi, Topological pumping of edge states via adia- batic passage, Physical Review B99, 155150 (2019)

    2019

  35. [35]

    X. Liu, Z. Lin, W. Song, J. Sun, C. Huang, S. Wu, X. Xiao, H. Xin, S. Zhu, and T. Li, Perfect excitation of topological states by supersymmetric waveguides, Phys- ical Review Letters132, 016601 (2024)

    2024

  36. [36]

    M. Dinu, F. Quochi, and H. Garcia, Third-order non- linearities in silicon at telecom wavelengths, Applied Physics Letters82, 2954 (2003)

    2003

  37. [37]

    J. Wang, D. Bonneau, M. Villa, J. W. Silverstone, R. Santagati, S. Miki, T. Yamashita, M. Fujiwara, M. Sasaki, H. Terai, M. G. Tanner, C. M. Natarajan, R. H. Hadfield, J. L. O’Brien, and M. G. Thompson, Chip-to- chip quantum photonic interconnect by path-polarization interconversion, Optica3, 407 (2016)

    2016

  38. [38]

    Maeder, R

    A. Maeder, R. J. Chapman, A. Sabatti, G. Finco, J. Kell- ner, and R. Grange, Programmable Bell state generation in an integrated thin film lithium niobate circuit, Light: Science & Applications15, 43 (2026)

    2026