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arxiv: 2604.18924 · v2 · submitted 2026-04-21 · 🧮 math.NA · cs.NA· quant-ph

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Lindbladian Homotopy Analysis Method to Solve Nonlinear Partial Differential Equations

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Pith reviewed 2026-05-10 02:39 UTC · model grok-4.3

classification 🧮 math.NA cs.NAquant-ph
keywords Lindbladian dynamicshomotopy analysis methodnonlinear partial differential equationsquantum simulationdensity matrixBurgers equationlogarithmic scaling
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The pith

The Lindbladian homotopy analysis method solves nonlinear PDEs by converting them to linear systems that embed in density matrices with only logarithmic growth in Hilbert space dimension.

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

The paper presents LHAM as a quantum approach for nonlinear PDEs. It first uses the homotopy analysis method to turn the nonlinear equation into a sequence of linear PDEs. These are then assembled into a higher-dimensional block-triangular linear system that is placed inside a density matrix and evolved under Lindbladian dynamics. The central advantage claimed is that the needed Hilbert space dimension grows only logarithmically with the inverse of the target truncation error, in contrast to the polynomial growth of Carleman linearization or Koopman-von Neumann methods. A sympathetic reader would care because this scaling could make quantum simulation of nonlinear flows and similar problems feasible with far fewer qubits than current linearization techniques require.

Core claim

The original nonlinear problem is first converted to a recursive sequence of linear PDEs with the homotopy analysis method and reformulated as a higher-dimensional lower block triangular linear homogeneous autonomous system. The solution is then embedded in the density matrix and obtained through the Lindbladian dynamics simulation. Compared to other methods such as Carleman linearization and the Koopman-von Neumann approach where the dimension of Hilbert space increases polynomially with the inverse of truncation error, the Hilbert space dimension in LHAM increases only logarithmically. LHAM is demonstrated with nonlinear PDEs including Burgers' equation and reduced magnetohydrodynamics.

What carries the argument

Lindbladian homotopy analysis method, which reformulates the nonlinear PDE as a higher-dimensional lower block triangular linear system embedded in a density matrix for Lindbladian evolution.

Load-bearing premise

The nonlinear PDE can be converted to a recursive sequence of linear PDEs via homotopy analysis and faithfully embedded into a density matrix for Lindbladian simulation without significant convergence or accuracy loss.

What would settle it

For Burgers' equation, compute the effective Hilbert-space dimension needed to reach truncation error epsilon and check whether the dimension scales as log(1/epsilon) or faster.

Figures

Figures reproduced from arXiv: 2604.18924 by Eunsik Choi, Jungin E. Kim, Xueling Lu, Yan Wang.

Figure 1
Figure 1. Figure 1: RMS error of solving Burgers’ equation with LHAM 0      00 00 0 00  L      0 [PITH_FULL_IMAGE:figures/full_fig_p011_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Relative L2 norm error of solving Burgers’ equation with LHAM 4.2. Magnetohydrodynamics. Magnetohydrodynamics (MHD) is a model of electrically conducting fluids that treats charged particles as a continuous fluid. The reduced MHD equa￾tions, which are applicable for incompressible fluids, are described by a coupled system of nonlinear PDEs defined as (52) ∂ω ∂t = ν∇2ω −  ∂φ ∂x ∂ω ∂y − ∂φ ∂y ∂ω ∂x  +  ∂ξ… view at source ↗
Figure 3
Figure 3. Figure 3: Calculated u values from Burgers’ equation with FDM and LHAM at different truncation orders where ζ(x, y, t) is the current density. The linear components of Eq. (52) are the diffusive terms ν∇2ω and η∇2 ξ, while the nonlinear components describe fluid advection and magnetic coupling. The Hilbert space is defined as H = L 2 (Ω) × L 2 (Ω) on the periodic two-dimensional domain Ω = [0, 2π) 2 . After the func… view at source ↗
Figure 4
Figure 4. Figure 4: LHAM RMS error: reduced MHD equations. 0    0 00 0 00 0   L  [PITH_FULL_IMAGE:figures/full_fig_p013_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: LHAM relative L2 norm error: reduced MHD equations. 5. Conclusions Most of the existing linearization-based quantum nonlinear ODE/PDE solvers face the scal￾ability challenge since the state space dimension increases exponentially. In this paper, a new quantum method, LHAM, is proposed to solve nonlinear ODEs/PDEs. In LHAM, a linear homogeneous autonomous system is constructed and the dimension of the state… view at source ↗
Figure 6
Figure 6. Figure 6: ω field profile of LHAM and classical pseudo-spectral method re￾sults with the error. 0   [PITH_FULL_IMAGE:figures/full_fig_p014_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: ξ field profile of LHAM and classical pseudo-spectral method re￾sults with the error. which the introduced auxiliary spatial variables or solution fields increase the state dimension combinatorially, because of the secondary linearization. To simulate non-unitary dynamics in the linearized PDEs, as few as two ancilla qubits are needed for the Lindbladian dynamics simulation. In contrast, the required numbe… view at source ↗
read the original abstract

Quantum scientific computing is to solve engineering and science problems such as simulation and optimization on quantum computers. Solving ordinary and partial differential equations (PDEs) is essential in simulations. However, existing quantum approaches to solve nonlinear PDEs suffer from the issues of curse of dimensionality and convergence during the linearization process. In this paper, a Lindbladian homotopy analysis method (LHAM) is proposed as a quantum differential equation solver to simulate non-unitary and nonlinear dynamics. The original nonlinear problem is first converted to a recursive sequence of linear PDEs with the homotopy analysis method and reformulated as a higher-dimensional lower block triangular linear homogeneous autonomous system. The solution is then embedded in the density matrix and obtained through the Lindbladian dynamics simulation. Compared to other methods such as Carleman linearization and the Koopman-von Neumann approach where the dimension of Hilbert space increases polynomially with the inverse of truncation error, the Hilbert space dimension in LHAM increases only logarithmically. LHAM is demonstrated with nonlinear PDEs including Burgers' equation and reduced magnetohydrodynamics equations.

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 the Lindbladian Homotopy Analysis Method (LHAM) as a quantum solver for nonlinear PDEs. The nonlinear problem is converted via the homotopy analysis method into a recursive sequence of linear PDEs, reformulated as a higher-dimensional lower block-triangular linear homogeneous autonomous system, and embedded into a density matrix whose evolution is simulated under Lindbladian dynamics. The central claim is that the effective Hilbert-space dimension scales only logarithmically with the inverse truncation error, in contrast to the polynomial scaling of Carleman linearization and Koopman-von Neumann methods. The approach is illustrated on Burgers' equation and reduced magnetohydrodynamics equations.

Significance. If the logarithmic scaling can be placed on a rigorous footing with explicit error bounds, LHAM would represent a meaningful advance in quantum algorithms for nonlinear dynamics by alleviating the curse of dimensionality that affects existing linearization techniques. The combination of homotopy analysis with Lindbladian embedding is technically novel and could be useful for non-unitary quantum simulation tasks. The manuscript does not, however, supply machine-checked proofs, reproducible code, or falsifiable scaling predictions that would strengthen its contribution.

major comments (2)
  1. [Abstract] Abstract: the claim that 'the Hilbert space dimension in LHAM increases only logarithmically' with inverse truncation error is unsupported by any theorem, lemma, or explicit bound relating the number of homotopy terms (blocks) m to the truncation error ε. Without such a relation, the asserted advantage over Carleman linearization and Koopman-von Neumann methods cannot be verified.
  2. [Reformulation and embedding (Section 3)] The reformulation step: the manuscript states that the higher-dimensional block-triangular system 'exactly preserves the original dynamics' when embedded in the density matrix, yet provides no convergence analysis or error estimate for the embedding process itself. This assumption is load-bearing for the logarithmic-scaling claim and requires a quantitative bound.
minor comments (2)
  1. [Abstract and Introduction] The abstract and introduction would benefit from a brief statement of the specific convergence-control parameter used in the homotopy analysis and how its value is chosen for the numerical examples.
  2. [Method section] Notation for the block-triangular matrix and the Lindbladian generator should be introduced with an explicit equation number on first use to improve readability.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful and constructive review. The comments highlight important points regarding the rigor of our scaling claims and error analysis, which we will address in the revision. We outline our responses below.

read point-by-point responses
  1. Referee: [Abstract] Abstract: the claim that 'the Hilbert space dimension in LHAM increases only logarithmically' with inverse truncation error is unsupported by any theorem, lemma, or explicit bound relating the number of homotopy terms (blocks) m to the truncation error ε. Without such a relation, the asserted advantage over Carleman linearization and Koopman-von Neumann methods cannot be verified.

    Authors: We agree that the manuscript lacks an explicit theorem or lemma establishing a general relation between m and ε. The logarithmic scaling is motivated by the block-triangular reformulation, in which the effective dimension grows linearly with m, together with the fast practical convergence of the homotopy series (often requiring only modest m for small ε, as shown numerically for Burgers' equation and reduced MHD). However, this does not yet constitute a rigorous bound. In the revised manuscript we will add a dedicated subsection deriving truncation-error estimates for the homotopy series under standard assumptions on the convergence-control parameter, including conditions under which m = O(log(1/ε)) holds, thereby placing the claimed advantage on firmer footing. revision: yes

  2. Referee: [Reformulation and embedding (Section 3)] The reformulation step: the manuscript states that the higher-dimensional block-triangular system 'exactly preserves the original dynamics' when embedded in the density matrix, yet provides no convergence analysis or error estimate for the embedding process itself. This assumption is load-bearing for the logarithmic-scaling claim and requires a quantitative bound.

    Authors: The block-triangular reformulation is constructed to be algebraically exact for the infinite homotopy series, and the subsequent embedding into Lindbladian evolution on the density matrix is a mathematically equivalent representation of the linear system. We acknowledge, however, that the manuscript provides no quantitative error propagation analysis for the finite truncation at m terms. In the revision we will insert a convergence-analysis paragraph (or short subsection) that bounds the total discrepancy between the original nonlinear solution and the truncated Lindbladian trajectory, explicitly relating the embedding error to the homotopy truncation error and confirming that the overall scaling remains logarithmic when the new bounds are satisfied. revision: yes

Circularity Check

0 steps flagged

No circularity: derivation builds on independent HAM and Lindbladian primitives without self-referential reduction

full rationale

The paper's chain converts a nonlinear PDE to a recursive sequence of linear PDEs via the homotopy analysis method, stacks them into a block-triangular linear system, and embeds the result in a density matrix whose evolution is governed by Lindbladian dynamics. None of these steps defines the target quantity (logarithmic Hilbert-space scaling) in terms of itself, fits a parameter to a subset and renames the fit as a prediction, or relies on a load-bearing self-citation whose content is unverified. The scaling comparison with Carleman/Koopman-von Neumann is asserted on the basis of the construction rather than derived from a fitted or self-referential quantity, so the derivation remains self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

1 free parameters · 2 axioms · 0 invented entities

The approach rests on standard assumptions from homotopy analysis and open quantum systems plus an ad hoc reformulation step whose validity is not independently evidenced in the abstract.

free parameters (1)
  • homotopy convergence control parameter
    Standard in homotopy analysis methods to ensure series convergence; value is typically chosen or fitted per problem.
axioms (2)
  • domain assumption Solutions to the sequence of linear PDEs exist and the homotopy series converges to the nonlinear solution
    Invoked when converting the original nonlinear problem to recursive linear PDEs.
  • ad hoc to paper The higher-dimensional block triangular reformulation exactly preserves the original dynamics when embedded in the density matrix
    Central step allowing Lindbladian simulation; introduced in the method description.

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Forward citations

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Reference graph

Works this paper leans on

38 extracted references · 7 canonical work pages · cited by 1 Pith paper

  1. [1]

    Quantum algorithm for nonlinear differential equations.arXiv preprint arXiv:2011.06571, 2020

    Seth Lloyd, Giacomo De Palma, Can Gokler, Bobak Kiani, Zi -W en Liu, Milad Marvian, Felix Tennie, and Tim Palmer. Quantum algorithm for nonlinear differential eq uations. arXiv preprint arXiv:2011.06571 , 2020

  2. [2]

    Embedding classical dynamics in a quantum computer

    Dimitrios Giannakis, Abbas Ourmazd, Philipp Pfeffer, J¨ org Schumacher, and Joanna Slawinska. Embedding classical dynamics in a quantum computer. Physical Review A , 105(5):052404, 2022

  3. [3]

    Linea r embedding of nonlinear dynamical systems and prospects for efficient quantum algorithms

    Alexander Engel, Graeme Smith, and Scott E Parker. Linea r embedding of nonlinear dynamical systems and prospects for efficient quantum algorithms. Physics of Plasmas , 28(6):062305, 2021

  4. [4]

    Efficient quantum algorithm for dissipative nonline ar differential equations

    Jin-Peng Liu, Herman Øie Kolden, Hari K Krovi, Nuno F Lour eiro, Konstantina Trivisa, and Andrew M Childs. Efficient quantum algorithm for dissipative nonline ar differential equations. Proceedings of the National Academy of Sciences , 118(35):e2026805118, 2021

  5. [5]

    Carleman li nearization approach for chemical kinetics integration toward quantum computation

    Takaki Akiba, Youhi Morii, and Kaoru Maruta. Carleman li nearization approach for chemical kinetics integration toward quantum computation. Scientific Reports , 13(1):3935, 2023

  6. [6]

    Qu antum algorithm for lattice boltzmann (qalb) simulation of incompressible fluids with a nonlinear collis ion term

    W ael Itani, Katepalli R Sreenivasan, and Sauro Succi. Qu antum algorithm for lattice boltzmann (qalb) simulation of incompressible fluids with a nonlinear collis ion term. Physics of Fluids , 36(1), 2024

  7. [7]

    Quantum al gorithms for nonlinear dynamics: Revisiting carleman linearization with no dissipative conditions

    Hsuan-Cheng W u, Jingyao W ang, and Xiantao Li. Quantum al gorithms for nonlinear dynamics: Revisiting carleman linearization with no dissipative conditions. SIAM Journal on Scientific Computing , 47(2):A943– A970, 2025

  8. [8]

    Quantum and classical alg orithms for nonlinear unitary dynamics

    Noah Brustle and Nathan Wiebe. Quantum and classical alg orithms for nonlinear unitary dynamics. Quan- tum, 9:1741, 2025

  9. [9]

    Quantum carleman lineariza- tion efficiency in nonlinear fluid dynamics

    Javier Gonzalez-Conde, Dylan Lewis, Sachin S Bharadwaj , and Mikel Sanz. Quantum carleman lineariza- tion efficiency in nonlinear fluid dynamics. Physical Review Research, 7(2):023254, 2025

  10. [10]

    Koopman–von neumann approach to quantum s imulation of nonlinear classical dynamics

    Ilon Joseph. Koopman–von neumann approach to quantum s imulation of nonlinear classical dynamics. Physical Review Research, 2(4):043102, 2020

  11. [11]

    On applications of qu antum computing to plasma simulations

    Ilya Y Dodin and Edward A Startsev. On applications of qu antum computing to plasma simulations. Physics of Plasmas , 28(9), 2021

  12. [12]

    Quantum algorithms for computing observables of nonlinear partial differential equations.arXiv preprint arXiv:2202.07834, 2022

    Shi Jin and Nana Liu. Quantum algorithms for computing o bservables of nonlinear partial differential equations. arXiv preprint arXiv:2202.07834 , 2022

  13. [13]

    Time complexity analysis o f quantum algorithms via linear representations for nonlinear ordinary and partial differential equations

    Shi Jin, Nana Liu, and Yue Yu. Time complexity analysis o f quantum algorithms via linear representations for nonlinear ordinary and partial differential equations. Journal of Computational Physics , 487:112149, 2023

  14. [14]

    Variational quantum algorithms for nonlinear problems

    Michael Lubasch, Jaewoo Joo, Pierre Moinier, Martin Ki ffner, and Dieter Jaksch. Variational quantum algorithms for nonlinear problems. Physical Review A , 101(1):010301, 2020

  15. [15]

    Solving nonlinear differential equations with differentiable quantum circuits

    Oleksandr Kyriienko, Annie E Paine, and Vincent E Elfvi ng. Solving nonlinear differential equations with differentiable quantum circuits. Physical Review A , 103(5):052416, 2021

  16. [16]

    Variational quantum algorithms for computational fluid dynamics

    Dieter Jaksch, Peyman Givi, Andrew J Daley, and Thomas R ung. Variational quantum algorithms for computational fluid dynamics. AIAA journal , 61(5):1885–1894, 2023

  17. [17]

    On quantum bsde solver fo r high-dimensional parabolic pdes

    Howard Su and Huan-Hsin Tseng. On quantum bsde solver fo r high-dimensional parabolic pdes. In 2025 IEEE International Conference on Quantum Computing and Eng ineering (QCE) , volume 2, pages 205–

  18. [18]

    On the homotopy analysis method for nonlin ear problems

    Shijun Liao. On the homotopy analysis method for nonlin ear problems. Applied mathematics and compu- tation, 147(2):499–513, 2004

  19. [19]

    Quantum homoto py perturbation method for nonlinear dissipative ordinary differential equations

    Cheng Xue, Yu-Chun W u, and Guo-Ping Guo. Quantum homoto py perturbation method for nonlinear dissipative ordinary differential equations. New Journal of Physics , 23(12):123035, 2021

  20. [20]

    Quantum homotopy analysis method with quantum-compatible linearization for nonlinear part ial differential equations

    Cheng Xue, Xiao-Fan Xu, Xi-Ning Zhuang, Tai-Ping Sun, Y un-Jie W ang, Ming-Yang Tan, Chuang-Chao Ye, Huan-Yu Liu, Yu-Chun W u, Zhao-Yun Chen, and Guo-Ping Guo . Quantum homotopy analysis method with quantum-compatible linearization for nonlinear part ial differential equations. Science China Physics, Mechanics & Astronomy , 68(10):104702, 2025. 16 CHOI, ET AL

  21. [21]

    Quantum homotopy algorithm for solving nonlinear pdes and flow probl ems

    Sachin S Bharadwaj, Balasubramanya Nadiga, Stephan Ei denbenz, and Katepalli R Sreenivasan. Quantum homotopy algorithm for solving nonlinear pdes and flow probl ems. arXiv preprint arXiv:2512.21033 , 2025

  22. [22]

    HAM-Schr¨ odingerisation: A generic fram ework of quantum simulation for any nonlinear pdes

    Shijun Liao. HAM-Schr¨ odingerisation: A generic fram ework of quantum simulation for any nonlinear pdes. Advances in Applied Mathematics and Mechanics , 18(1):1–10, 2026

  23. [23]

    Linear combination o f hamiltonian simulation for nonunitary dynamics with optimal state preparation cost

    Dong An, Jin-Peng Liu, and Lin Lin. Linear combination o f hamiltonian simulation for nonunitary dynamics with optimal state preparation cost. Physical Review Letters , 131(15):150603, 2023

  24. [24]

    Quantum simulation of part ial differential equations: Applications and detailed analysis

    Shi Jin, Nana Liu, and Yue Yu. Quantum simulation of part ial differential equations: Applications and detailed analysis. Physical Review A , 108(3):032603, 2023

  25. [25]

    Quantum simulation of part ial differential equations via schr¨ odingerization

    Shi Jin, Nana Liu, and Yue Yu. Quantum simulation of part ial differential equations via schr¨ odingerization. Physical Review Letters , 133(23):230602, 2024

  26. [26]

    Design ing a nearly optimal quantum algorithm for linear differential equations via lindbladians

    Zhong-Xia Shang, Naixu Guo, Dong An, and Qi Zhao. Design ing a nearly optimal quantum algorithm for linear differential equations via lindbladians. Physical Review Letters , 135(12):120604, 2025

  27. [27]

    Usage of the homotopy analysis method for solving the nonlinear and linear integral equati ons of the second kind

    Edyta Hetmaniok, Damian S/suppress lota, Tomasz Trawi´ nski, and Roman Witu/suppress la. Usage of the homotopy analysis method for solving the nonlinear and linear integral equati ons of the second kind. Numerical Algorithms , 67(1):163–185, 2014

  28. [28]

    A quantum algorithm to solve nonlinear differential equations.arXiv preprint arXiv:0812.4423, 2008

    Sarah K Leyton and Tobias J Osborne. A quantum algorithm to solve nonlinear differential equations. arXiv preprint arXiv:0812.4423 , 2008

  29. [29]

    Koopman operator in systems and control , volume 484

    Alexandre Mauroy, Y Susuki, and Igor Mezic. Koopman operator in systems and control , volume 484. Springer, 2020

  30. [30]

    Koopman spectral linearizati on vs

    Dongwei Shi and Xiu Yang. Koopman spectral linearizati on vs. carleman linearization: A computational comparison study. Mathematics, 12(14):2156, 2024

  31. [31]

    Challenges for quantum computation of nonlinear dynamical systems using linear representations

    Yen Ting Lin, Robert B Lowrie, Denis Aslangil, Yi˘ git Su ba¸ sı, and Andrew T Sornborger. Challenges for quantum computation of nonlinear dynamical systems usi ng linear representations. arXiv preprint arXiv:2202.02188, 2022

  32. [32]

    Barren plateaus in quantum neural network training landscapes

    Jarrod R McClean, Sergio Boixo, Vadim N Smelyanskiy, Ry an Babbush, and Hartmut Neven. Barren plateaus in quantum neural network training landscapes. Nature communications, 9(1):4812, 2018

  33. [33]

    Quantum algorithm for linear differential equations with exponentially improved dependence on precision

    Dominic W Berry, Andrew M Childs, Aaron Ostrander, and G uoming W ang. Quantum algorithm for linear differential equations with exponentially improved dependence on precision. Communications in Mathematical Physics , 356(3):1057–1081, 2017

  34. [34]

    Compac t quantum algorithms for time-dependent dif- ferential equations

    Sachin S Bharadwaj and Katepalli R Sreenivasan. Compac t quantum algorithms for time-dependent dif- ferential equations. Physical Review Research, 7(2):023262, 2025

  35. [35]

    Hamiltonian Simulation Using Linear Com- binations of Unitary Operations

    Andrew M Childs and Nathan Wiebe. Hamiltonian simulati on using linear combinations of unitary oper- ations. arXiv preprint arXiv:1202.5822 , 2012

  36. [36]

    Hu and S

    Qitong Hu and Shi Jin. Amplitude-phase separation towa rd optimal and fast-forwardable simulation of non-unitary dynamics. arXiv preprint arXiv:2602.09575 , 2026

  37. [37]

    Generic and scalable different ial-equation solver for quantum scientific com- puting

    Jinhwan Sul and Yan W ang. Generic and scalable different ial-equation solver for quantum scientific com- puting. Physical Review A , 111(1):012625, 2025

  38. [38]

    Simulating open qu antum systems using hamiltonian simulations

    Zhiyan Ding, Xiantao Li, and Lin Lin. Simulating open qu antum systems using hamiltonian simulations. PRX quantum , 5(2):020332, 2024. Appendix A. Duhamel’s Principle for Non-Hermitian Time Evolution The nonlinear partial differential equation (PDE) is written with an init ial value such as Eq. (1). In general, non-Hermitian M can be decomposed as Hermitia...