REVIEW 4 major objections 4 minor 29 references
Quantum Diffusion Model for Quark and Gluon Jet Generation
T0 review · 4 major / 4 minor · reviewed 2026-08-10 · deepseek-v4-flash
Pith's one-line read The paper claims that fully quantum and hybrid diffusion models generate quark and gluon jet images whose FID scores (2.7362 and 1.8123) are on par with a classical model's 1.8169.
desk verdict Applies quantum/hybrid DDPM-style models to CMS jets with open code, but the one-shot unitary 'noising' makes it an autoencoder in disguise, and the single-run FID does not support the competitiveness claim. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The load-bearing object is a one-shot random unitary scrambling step replacing the Gaussian noising process. A random unitary matrix is a reversible quantum operation, and sampling it uniformly from the space of quantum operations gives a scramble that is meant to destroy the original pixel structure the way repeated Gaussian noise would. The classical-to-quantum embedding uses $R_x$ rotation gates that encode groups of four pixels into four channels, and the denoising side uses a variational quantum circuit built from rotation and strongly entangling gates, kept identical across models, inserted inside a U-Net. The same circuit, with the number of layers as a tunable parameter, serves as the sole denoiser in the fully quantum model and as the middle layer of a convolutional U-Net in the hybrid model. Training minimizes the mean squared error between the model output and the clean image, which is the simplified diffusion objective.
What would settle it
Train this one-shot unitary quantum model and a conventional multi-step Gaussian diffusion model on identical 16x16 jet images, then measure whether the quantum model's samples remain distinguishable from the training set by a hold-out classifier and whether FID parity persists when the number of sampling steps and the amount of scrambling are varied; if the quantum model collapses to memorized or reconstructed examples, or if its samples are classified with near-perfect accuracy, the claim that it is a competitive diffusion model would be falsified.
Extended reading notes
Core claim
The central claim, stated on the paper's own terms, is empirical: a fully quantum diffusion model and a hybrid quantum-classical diffusion model generate quark and gluon jet images whose quality is competitive with a similar classical diffusion model. The forward diffusion process is changed from adding Gaussian noise over many timesteps to applying one random unitary matrix, sampled uniformly from the space of quantum operations, to each of four channels of an angle-encoded jet image; the denoising network is a U-Net whose core contains a variational quantum circuit with strongly entangling layers. After 50 epochs of training with mean squared error loss and the Adam optimizer, the final FID values are 1.8123 for the hybrid model, 2.7362 for the fully quantum model, and 1.8169 for the classical baseline. The authors therefore conclude that all or part of the deep neural network computations can in principle be moved to quantum processors without a performance trade-off. The paper does not claim a speedup; it claims parity in output quality.
Load-bearing premise
The load-bearing premise is that a single random reversible quantum operation applied to each channel behaves like the multi-step noise process of a diffusion model, an assumption the paper adopts from earlier work on arbitrary image transforms; if it fails, the competitive scores may reflect autoencoder-like reconstruction rather than genuine diffusion sampling.
Editorial extensions
If this is right
- If the parity result holds, quantum circuits can be placed inside the denoising stage of a diffusion model for physics data without a measurable drop in FID.
- The one-shot unitary forward process removes the need for many noising timesteps, because the random scramble is applied once per channel rather than iteratively.
- The single generated channel should extend to the full set of three subdetector channels per jet, a direction the paper explicitly leaves for future work.
- Moving the quantum layers to real quantum processors could reduce training time while keeping generative quality, though the paper supports this only as an implication, not by a runtime measurement.
- The FID plateau across all models suggests that data sparsity is the limiting factor, so keeping only the most prominent pixel values in a post-processing step could sharpen the generated jets.
Reading between the lines
- Editorial extension: because a unitary is invertible and preserves information, one application does not progressively destroy data the way Gaussian noise does; the reported FID parity may therefore be evidence of autoencoder-like reconstruction rather than diffusion sampling, a distinction the paper does not test.
- Editorial extension: a direct comparison with a classical one-shot denoiser trained on the same single-step scramble would isolate whether the quantum circuit adds capability beyond a classical network of comparable size.
- Editorial extension: a sharper evaluation would measure sample diversity and mode coverage, for example with a hold-out classifier trained to distinguish generated jets from training jets, since FID alone can miss memorization or collapse.
- Editorial extension: because the experiments use simulators, the FID parity does not by itself imply any computational saving; the practical value depends on the speed and cost of future quantum hardware.
Signed reviews
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper proposes fully quantum, hybrid, and fully classical denoising diffusion models for CMS quark and gluon jet images. In the forward process, Gaussian noise is replaced by a single Haar-random unitary applied once per encoded channel; the denoiser is a U-Net with variational quantum circuit layers. Experiments on 1,000 16x16 ECAL jet images report final FID values of 1.8169 (classical), 1.8123 (hybrid), and 2.7362 (fully quantum), and the authors conclude that the quantum models are competitive with the classical model.
Significance. If the central claims hold, this would be a useful empirical demonstration of quantum circuits in a generative model for LHC data: the paper provides an open-source code repository and a direct comparison of classical, hybrid, and fully quantum variants on a physics dataset. However, the significance is currently limited by the absence of a derivation connecting the one-shot unitary forward process to a diffusion objective, by the lack of statistical uncertainty in the central FID comparison, and by the absence of any runtime or resource measurements supporting the stated computational motivation.
major comments (4)
- [§4.2, Eq. (5)] The quantum forward process is never defined as a conditional distribution q(x_t|x_0). Replacing Gaussian noise with Haar-random unitaries is not a noising operation unless a measurement is specified; if the unitary is followed by a computational-basis measurement, q becomes a discrete distribution, and if it is not, the denoiser input is a quantum state rather than the classical image the U-Net receives. In neither case is the KL divergence D_KL(q(x_T|x_0) || p(x_T)) in Eq. (5) shown to be finite or meaningful, and the one-shot unitary does not reproduce the multi-step schedule of Eqs. (1)-(3). The citation to cold diffusion [29] does not resolve this, because cold diffusion requires a sequence of degradation operators with increasing information loss; a unitary is invertible and norm-preserving. As written, the model is closer to an autoencoder that inverts a random linear map, so the central claim that the paper builds a quantum diffusion model is unsupported.
- [§5–§6, FID results] The empirical comparison rests on single FID numbers (1.8169, 1.8123, 2.7362) with no error bars, no number of random seeds, no held-out split, and no description of how many generated samples are used for FID or whether the evaluation set was seen during training. The fully quantum value is about 50% worse than the classical one, so the word “competitive” requires at least a statistical test or a predefined acceptance threshold. This is load-bearing because the abstract's claim is an empirical one.
- [§1, §6] The stated motivation is to mitigate the computational challenges of diffusion models, but the paper reports no wall-clock training time, no qubit counts or circuit depth, no simulation cost, and no comparison of quantum or hybrid training overhead against the classical baseline. Since all experiments are simulations, the concluding suggestion that computations can be offloaded to faster quantum processors to reduce training time is not supported by any measurement in the manuscript.
- [§4.2, §6] The paper does not compare against a non-diffusion baseline such as a classical autoencoder with the same U-Net. Since the one-shot unitary forward map is invertible, the reported FID could in principle be achieved by learning the inverse map plus training-set statistics; an autoencoder baseline would show whether the generative formulation is doing any work. This comparison is also needed to test the assertion in Section 4.2 that the choice of forward scrambling does not significantly impact model performance.
minor comments (4)
- [§8] The section heading “Data A vailability” contains a typo and an extra space; it should read “Data Availability.”
- [§2.3] The dataset description mentions ECAL, HCAL, and reconstructed tracks, but the experiments use only 1,000 ECAL-detected jets cropped to 16x16 pixels; please state explicitly whether the other subdetector channels are discarded and how the 1,000-jet subset is selected.
- [§2.2] The phrase “Haar measurement” is nonstandard: the Haar measure is a distribution over unitary matrices, not a measurement. Please clarify the intended terminology and define the operation precisely in the quantum forward process.
- [§1, Refs. [4,26]] Reference [26] is cited as an example of molecular biology applications, but the title concerns dental smile analysis; please correct the citation or adjust the example.
Circularity Check
No significant circularity: the central competitiveness claim rests on an external FID benchmark, not on a fitted constant or a self-citation chain.
full rationale
The paper's central claim is empirical: fully quantum and hybrid models achieve FID scores of 2.7362 and 1.8123, respectively, compared with 1.8169 for a classical model on CMS quark-gluon jet images. These scores are measured with an external metric (FID) against an external dataset, and no equation in the paper reduces these numbers to a fitted parameter or to the model's own assumptions. The forward process uses Haar random unitaries inspired by reference [15] and justified by reference [29], but even if this is conceptually questionable as a diffusion noising process, it is an imported design choice rather than a circular reduction: the competitive result does not follow by construction from that choice. The only self-citations, [7] and [24], appear in background enumerations of generative diffusion applications and variational quantum circuit uses; they are not load-bearing for the benchmark result. No uniqueness theorem or author-imported ansatz is invoked to force the conclusion. Any concern about whether a one-shot unitary can serve as a valid forward diffusion process is a validity/correctness issue, not a circularity issue.
Assumptions & free parameters
free parameters (5)
- VQC layer count =
not reported
- Qubit count per channel =
not reported
- Quantum embedding grouping =
groups of four pixels, four channels
- Dataset crop and subset =
1000 jets cropped to 16x16 pixels
- Training epochs =
50
assumptions (5)
- domain assumption Arbitrary unitary noising can serve as the forward diffusion process, and a VQC denoiser can learn the reverse
- ad hoc to paper A single Haar unitary applied once per channel is equivalent in effect to a multi-step noising schedule
- domain assumption Angle encoding with Rx rotations preserves the information needed for jet generation, and measurement statistics are sufficient
- domain assumption FID on 16x16 pixel images is a valid quality metric for this task
- domain assumption Classical simulators of quantum circuits faithfully represent the proposed quantum models
Cite this review
Pith. "Pith review of Quantum Diffusion Model for Quark and Gluon Jet Generation." pith.science (2026). https://pith.science/paper/XVP6SMKV
@misc{pith2026241221082,
author = {Pith},
title = {Pith review of: Quantum Diffusion Model for Quark and Gluon Jet Generation},
year = {2026},
howpublished = {\url{https://pith.science/paper/XVP6SMKV}},
note = {Machine review of arXiv:2412.21082}
}
read the original abstract
Diffusion models have demonstrated remarkable success in image generation, but they are computationally intensive and time-consuming to train. In this paper, we introduce a novel diffusion model that benefits from quantum computing techniques in order to mitigate computational challenges and enhance generative performance within high energy physics data. The fully quantum diffusion model replaces Gaussian noise with random unitary matrices in the forward process and incorporates a variational quantum circuit within the U-Net in the denoising architecture. We run evaluations on the structurally complex quark and gluon jets dataset from the Large Hadron Collider. The results demonstrate that the fully quantum and hybrid models are competitive with a similar classical model for jet generation, highlighting the potential of using quantum techniques for machine learning problems.
Figures
Figures from the paper (3 more)
Reference graph
Works this paper leans on
-
[29]
Cold diffusion: Inverting arbitrary image transforms without noise
Arpit Bansal, Eitan Borgnia, Hong-Min Chu, Jie Li, Hamid Kazemi, Furong Huang, Micah Goldblum, Jonas Geiping, and Tom Goldstein. Cold diffusion: Inverting arbitrary image transforms without noise. In Advances in Neural Information Processing Systems, volume 36, 2024. 8
work page 2024
-
[15]
Generative quantum machine learning via denoising diffusion probabilistic models
Bingzhi Zhang, Peng Xu, Xiaohui Chen, and Quntao Zhuang. Generative quantum machine learning via denoising diffusion probabilistic models. In Physical Review Letters, volume 132, number 10, pages 100602, 2024. 7 Quantum Diffusion Model for Quark and Gluon Jet Generation A PREPRINT
work page 2024
-
[28]
Towards Efficient Quantum Hybrid Diffusion Models
Francesca De Falco, Andrea Ceschini, Alessandro Sebastianelli, Bertrand Le Saux, and Massimo Panella. Towards Efficient Quantum Hybrid Diffusion Models. In arXiv preprint arXiv:2402.16147, 2024
arXiv 2024
-
[1]
Hanqun Cao, Cheng Tan, Zhangyang Gao, Yilun Xu, Guangyong Chen, Pheng-Ann Heng, and Stan Z. Li. A survey on generative diffusion models. In IEEE Transactions on Knowledge and Data Engineering , volume 36, number 7, pages 2814–2830, 2024
work page 2024
-
[2]
Diffusion models beat gans on image synthesis
Prafulla Dhariwal and Alexander Nichol. Diffusion models beat gans on image synthesis. In Advances in Neural Information Processing Systems, volume 34, pages 8780–8794, 2021
2021
-
[3]
Diffused heads: Diffusion models beat gans on talking-face generation
Michał Stypułkowski, Konstantinos V ougioukas, Sen He, Maciej Zi˛ eba, Stavros Petridis, and Maja Pantic. Diffused heads: Diffusion models beat gans on talking-face generation. In Proceedings of the IEEE/CVF Winter Conference on Applications of Computer Vision (WACV), pages 5091–5100, 2024
work page 2024
-
[4]
Tan, Chia-Jung Hsu, and Ye Zhu
Duo Xu, Jonathan C. Tan, Chia-Jung Hsu, and Ye Zhu. Denoising diffusion probabilistic models to predict the density of molecular clouds. In The Astrophysical Journal, volume 950, number 2, pages 146, 2023
work page 2023
-
[5]
Qiu, Marian Axente, Chih-Wei Chang, Junbo Peng, Ashish B
Shaoyan Pan, Tonghe Wang, Richard L.J. Qiu, Marian Axente, Chih-Wei Chang, Junbo Peng, Ashish B. Patel, Joseph Shelton, Sagar A. Patel, Justin Roper, and others. 2D medical image synthesis using transformer-based denoising diffusion probabilistic model. In Physics in Medicine & Biology , volume 68, number 10, pages 105004, 2023
work page 2023
Show all 29 references
-
[6]
Graph denoising diffusion for inverse protein folding
Kai Yi, Bingxin Zhou, Yiqing Shen, Pietro Liò, and Yuguang Wang. Graph denoising diffusion for inverse protein folding. In Advances in Neural Information Processing Systems , volume 36, 2024
2024
-
[7]
Toomey, Hanna Parul, and Sergei Gleyzer
Pranath Reddy, Michael W. Toomey, Hanna Parul, and Sergei Gleyzer. A conditional diffusion model for super- resolution of gravitational lensing data. In arXiv preprint arXiv:2406.08442, 2024
2024 arXiv
-
[8]
Improved denoising diffusion probabilistic models
Alexander Quinn Nichol and Prafulla Dhariwal. Improved denoising diffusion probabilistic models. InInternational Conference on Machine Learning, pages 8162–8171, 2021
2021
-
[9]
Denoising diffusion implicit models
Jiaming Song, Chenlin Meng, and Stefano Ermon. Denoising diffusion implicit models. In arXiv preprint arXiv:2010.02502, 2020
2010 arXiv
-
[10]
Denoising diffusion restoration models
Bahjat Kawar, Michael Elad, Stefano Ermon, and Jiaming Song. Denoising diffusion restoration models. In Advances in Neural Information Processing Systems , volume 35, pages 23593–23606, 2022
2022
-
[11]
Sohaib Alam, Guillermo Alonso-Linaje, B
Ville Bergholm, Josh Izaac, Maria Schuld, Christian Gogolin, Shahnawaz Ahmed, Vishnu Ajith, M. Sohaib Alam, Guillermo Alonso-Linaje, B. AkashNarayanan, Ali Asadi, and others. Pennylane: Automatic differentiation of hybrid quantum-classical computations. In arXiv preprint arXiv...
2018 arXiv
-
[12]
Quantum machine learning: a classical perspective
Carlo Ciliberto, Mark Herbster, Alessandro Davide Ialongo, Massimiliano Pontil, Andrea Rocchetto, Simone Severini, and Leonard Wossnig. Quantum machine learning: a classical perspective. In Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences , v...
2018
-
[13]
An introduction to quantum machine learning
Maria Schuld, Ilya Sinayskiy, and Francesco Petruccione. An introduction to quantum machine learning. In Contemporary Physics, volume 56, number 2, pages 172–185, 2015
2015
-
[14]
Denoising diffusion probabilistic models
Jonathan Ho, Ajay Jain, and Pieter Abbeel. Denoising diffusion probabilistic models. In Advances in Neural Information Processing Systems, volume 33, pages 6840–6851, 2020
2020
-
[16]
Deep unsupervised learning using nonequilibrium thermodynamics
Jascha Sohl-Dickstein, Eric Weiss, Niru Maheswaranathan, and Surya Ganguli. Deep unsupervised learning using nonequilibrium thermodynamics. In International Conference on Machine Learning , pages 2256–2265, 2015
2015
-
[17]
Der massbegriff in der theorie der kontinuierlichen gruppen
Alfred Haar. Der massbegriff in der theorie der kontinuierlichen gruppen. In Annals of Mathematics, volume 34, number 1, pages 147–169, 1933
1933
-
[18]
Quantum machine learning
Jacob Biamonte, Peter Wittek, Nicola Pancotti, Patrick Rebentrost, Nathan Wiebe, and Seth Lloyd. Quantum machine learning. In Nature, volume 549, number 7671, pages 195–202, 2017
2017
-
[19]
Nielsen and Isaac L
Michael A. Nielsen and Isaac L. Chuang. Quantum Computation and Quantum Information. Cambridge University Press, 2002
2002
-
[20]
Variational quantum circuits for deep reinforcement learning
Samuel Yen-Chi Chen, Chao-Han Huck Yang, Jun Qi, Pin-Yu Chen, Xiaoli Ma, and Hsi-Sheng Goan. Variational quantum circuits for deep reinforcement learning. In IEEE access, volume 8, pages 141007–141024, 2020
2020
-
[21]
Variational quantum circuits for machine learning
Israel Griol-Barres, Sergio Milla, Antonio Cebrián, Yashar Mansoori, and José Millet. Variational quantum circuits for machine learning. an application for the detection of weak signals. In Applied Sciences, volume 11, number 14, pages 6427, 2021
2021
-
[22]
Variational quantum generators: Generative adversarial quantum machine learning for continuous distributions
Jonathan Romero and Alán Aspuru-Guzik. Variational quantum generators: Generative adversarial quantum machine learning for continuous distributions. In Advanced Quantum Technologies, volume 4, number 1, pages 2000003, 2021
2021
-
[23]
Variational Quantum Circuits Enhanced Generative Adversarial Network
Runqiu Shu, Xusheng Xu, Man-Hong Yung, and Wei Cui. Variational Quantum Circuits Enhanced Generative Adversarial Network. In arXiv preprint arXiv:2402.01791, 2024
2024 arXiv
-
[24]
Quantum Vision Transformers for Quark–Gluon Classification
Mar´cal Comajoan Cara, Gopal Ramesh Dahale, Zhongtian Dong, Roy T Forestano, Sergei Gleyzer, Daniel Justice, Kyoungchul Kong, Tom Magorsch, Konstantin T Matchev, Katia Matcheva, and others. Quantum Vision Transformers for Quark–Gluon Classification. In Axioms, volume 13, numbe...
2024
-
[25]
Burkle, S
Michael Andrews, John Alison, Sitong An, B. Burkle, S. Gleyzer, M. Narain, M. Paulini, B. Poczos, and E. Usai. End-to-end jet classification of quarks and gluons with the CMS Open Data. In Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectromete...
2020
-
[26]
Mirror, Mirror on the Wall: Automating Dental Smile Analysis with AI in Smart Mirrors
Mariia Baidachna, Haneen Fatima, Rahaf Omran, Nour Ghadban, Muhammad Ali Imran, Ahmad Taha, and Lina Mohjazi. Mirror, Mirror on the Wall: Automating Dental Smile Analysis with AI in Smart Mirrors. In Computing&AI Connect, volume 1, number 1, pages 1–10. Scifiniti, 2024
-
[27]
GANs trained by a two time-scale update rule converge to a local Nash equilibrium
Martin Heusel, Hubert Ramsauer, Thomas Unterthiner, Bernhard Nessler, and Sepp Hochreiter. GANs trained by a two time-scale update rule converge to a local Nash equilibrium. In Advances in Neural Information Processing Systems, volume 30, 2017
2017
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