Rene-Marcel Lehner

  • Computational Physics
  • Research Visualization
  • AI

My passion is to build mathematical and physical models and to apply them to real-world problems.
Along the way, I love creating interactive scientific visualizations, applications, and websites.
After my M.Sc. in theoretical physics, I now focus on machine learning, neural network architectures, and tensor networks.

Portrait of Rene-Marcel Lehner

  • M.Sc. Physics
  • Python
  • PyTorch
  • Rust
  • TypeScript

Projects

  • Robotics
  • Machine learning
  • Theory
  1. The Blaze2D flame as a glowing glass sculpture, orange above a blue wave, on black

    Strongest Research Artifact

    Blaze2D

    Software that computes how light travels through photonic crystals.

    2025 – present
  2. Two dotted lattices turning against each other, their overlap forming a shifting moiré pattern

    Master Thesis

    Envelope Approximation for Photonic Moiré Crystals

    A theory for light in twisted photonic crystals.

    2025 – present
  3. The Essen-Ruhr terrain in 3D, heights stretched five times, turning slowly while the map changes from height to streams to geology

    GeoNeural

    Compressing landscapes with neural terrain coders, and using geophysics to help reduce their errors.

    2026 – present
  4. The assembled follower arm, a printed six-joint arm with a two-finger gripper

    Recover in Real Time

    Two robot arms I assembled for a study on recovering from mistakes and delays; so far only human-controlled.

    2026 – present
  5. A simulated two-link arm (solid) and the physics model’s prediction from 0.3 s earlier (faded); the gap between the two hands is the residual

    Residual Worlds

    A neural network learns to fix a physics model’s errors, tested by steering a simulated robot arm.

    2026 – present
  6. A grayscale test face beside a bar chart of DenseNet’s probability for each of seven emotions; the face changes between happy, surprise and neutral, the bars move with it, and a color map fades in over each face, brightest where graying out the face lowers DenseNet’s confidence the most

    Facial Emotion Recognition

    Computer vision: seven network types learn to read emotions from faces, then get tuned, trained longer and compressed.

    2024 and 2026
  7. Two AI agents in the same maze, told to go to the grey box, after the same forced action change: the one trained with extra demonstrations runs out of steps, the one trained with corrections reaches the box

    Grounded Recovery (the project’s own website, opens in a new tab)

    Imitation learning: are a limited number of expert labels better spent on more examples, or on corrections after mistakes?

    2026
  8. A box of hard spheres settling under gravity: a regular lattice at first, then layers of green and red crystal growing at the bottom under a gray fluid

    Team Project

    Hard Sphere Simulations

    A team study of hard spheres: a faster collision search and sedimentation under gravity.

    2024
  9. Particles aligning into flocks under the sampled neighbor rule

    Bachelor Thesis

    Neural Swarm Dynamics

    An attempt to form swarms with multi-agent reinforcement learning, and a neural-network-friendly Monte Carlo rule.

    2023