Q2B26 Copenhagen | Milan Liepelt, New Technologies Development Lead, ARTIDIS

Q2B26 Copenhagen | Milan Liepelt, New Technologies Development Lead, ARTIDIS

🎙 Milan Liepelt 👥 6K 📅 October 12, 2026 ⏱ 16 min 👁 90 📄 original study 🧭 2026-10-15
Available in: English (current) Français

Keywords

quantum GANdata augmentationspectral biashybrid quantum-classicaltraining stability

Summary

In this talk presented at Q2B26 Copenhagen, Milan Liepelt from ARTIDIS describes a journey of designing a hybrid quantum GAN for medical data augmentation. The architecture combines an autoencoder with a GAN, where the generator is a parameterized quantum circuit. Initial experiments revealed a surprising exponential scaling of the required classical discriminator size relative to the quantum generator size, hinting at a potential quantum advantage. However, this result did not hold when the autoencoder was modified, and a persistent performance gap remained. Liepelt then found a paper on spectral amplitude principles that explains fundamental differences between classical and quantum neural network training: classical networks exhibit spectral bias (learning low frequencies first) while quantum networks prioritize highest amplitude frequencies from the start. This explained the training instability and the stagnation observed. By measuring the discriminator’s bandwidth and applying interventions—training a small discriminator for longer and using random Fourier features—training was stabilized, achieving competitive results. The talk concludes that quantum GANs may excel on datasets with large spectral bandwidth, a promising avenue for future work.

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Critical Evaluation

Value of the Information & Strength of the Argument

The talk provides a well-structured narrative with empirical evidence. The initial surprising result is rigorously tested and eventually explained through a theoretical framework. The reasoning is logical: from observation of exponential scaling to hypothesis about spectral bias, then to validation via bandwidth measurement and successful interventions. The argument is convincing because it alternates between experiments and theoretical interpretation, and the interventions demonstrably fix the training issues. The presentation is clear and the scientific method is applied appropriately.

Scientific Rigor, Source Quality, Title Accuracy

The speaker cites two key sources: a paper from CERN for the GAN architecture and a paper on spectral amplitude principles, though specific references are not fully given. The description includes a link to the Q2B conference website as a supplementary resource. The title is functional but lacks descriptive detail; the description provides a better summary. The talk is presented at a professional conference, indicating a certain level of scrutiny, but it is not peer-reviewed. The methodology appears rigorous, with repeated experiments and careful controls, though the description of the experiments could be more detailed.

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Title / Content Match

The title accurately identifies the speaker, event, and topic, while the description provides a more specific subtitle about the content.

Quality & Reliability

8/10

The talk presents original experimental results with reproducible evidence, though it is not peer-reviewed. The methodology is transparent and the reasoning from spectral bias principles to interventions is sound. Minor limitations include the lack of full references to cited papers.

Key Moments

Cited Sources

  • Q2B Conference website — Official conference page for Q2B26 Copenhagen
  • CERN paper on autoencoder-based GAN — Architecture for the hybrid quantum GAN was first published from CERN, as mentioned in the talk
  • Spectral amplitude principles for dynamics of quantum neural networks — Paper that provides the theoretical basis for the observed spectral mismatch

Contribution & Novelties

The talk offers an original contribution by connecting spectral bias theory to the practical challenge of stabilizing quantum GAN training. It provides empirical evidence that the mismatch between classical and quantum training principles can be exploited to design better hybrid models. The proposed interventions (carefully sized and trained discriminators, random Fourier features) are practical and potentially transferable. The work also suggests that quantum generators are particularly suited for data with large spectral bandwidth, which is an open question.

Pour aller plus loin :

  • Quantum machine learning — Discusses the broader field and challenges.
  • Generative adversarial network — Foundational concept for GANs.
  • Spectral bias in neural networks — Overview of the phenomenon central to the talk.
  • Parameterized quantum circuit — The architecture used for the quantum generator.

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Radar Profile

The radar profile shows high technical level and reliability relative to the moderate amount of information, indicating a dense, specialized presentation with strong methodological grounding.

Reliability 8/10