Jonathan Cassens

ML Engineer at Kpler, London

Jonathan Cassens

I build ML platforms and the models that run on them. Physicist by training. Matrices <3

Four histograms of momentum, total energy, beam radius and azimuthal angle. The orange WGAN-GP synthetic outline sits on top of the blue real Monte Carlo distribution in each panel, including the long tails.
My MRes project. A physics-constrained GAN (orange) reproducing Monte Carlo truth (blue) for the COMET particle beam, six species mixed.Code
01

Experience

  1. Now

    ML Engineer, Kpler

    Commodities tribe

    • Led the SageMaker evaluation end to end, through to reporting: training and serving models via MLflow, Studio spaces, image dependencies, and role and permission scoping.
    • Validated data access on the new CDC and dbt pipelines through Redshift.
    • Contributing to the move off Dataiku to our own ML platform and kpler CLI.
    • Improving the EBX, EBD and EBA models through feature engineering and model design.

    SageMaker · MLflow · Redshift · dbt · Kafka · S3 · Iceberg · IAM · PostgreSQL

  2. 2026

    AI Engineering Intern, Medly AI

    • Production pipelines for an AI tutor with 300k+ users.
    • A question difficulty transformer driving personalised question assignment.
    • An LLM student simulator and eval framework, plus SummaryEval, an LLM-judge quality gate.
  3. Feb to Jun 2026

    GenAI Alignment Engineer, Google via QualityAI

    • Physics data curation for LLM pedagogy alignment.
    • Failure-report triage pipeline: routing over 91% faster.
  4. Summer 2023

    Software Development Placement, Sky

    • React component refresh that cut content tagging time by 17%.

Education

  1. 2025 to 2026

    MRes Machine Learning and Big Data in the Physical Sciences

    Imperial College London

    Statistics, applied ML and accelerated processing. Research project: the particle beam GAN above.

  2. BSc, 2:1

    Theoretical Physics

    UCL

    Quantum mechanics, statistical and particle physics, computational physics, ML for physicists.

  3. Bootcamp

    Software Engineering

    Imperial College London. Full scholarship, 97th percentile.

02

Projects

MRes research · Physics · GANs · HPC

COMET particle beam GAN

A physics-constrained WGAN-GP that stands in for slow Monte Carlo simulation of the COMET beam. ROOT-to-parquet ingestion, HTCondor training, and C2ST, MMD and tail tests to prove the synthetic beam matches the real one. The figure at the top is its output.

200M+datapoints trained on
6particle species, mixed at the true ratio
  • Medly AI · Transformers · IRT

    Question difficulty transformer

    Predicts question difficulty so each student gets one pitched at the right level.

    ~90% in bracket · 99%+ within one

  • Trading · Game theory

    IMC Prosperity 04

    Market making, ETF arbitrage and game-theoretic allocation.

    Top 1% manual · top 2% algo

  • Hardware-aware ML

    Wildfire detection on an FPGA

    A pruned, INT4-quantised CNN deployed through ONNX and HLS4ML.

    405k params · ~94% recall

  • LLMs · Evals

    Context Pareto

    Accuracy against tokens for long-context compression strategies.

    Public

  • Monte Carlo · Football

    FPL modelling engine

    AI-native Monte Carlo simulation of my Fantasy Premier League team.

    ~500k global rank, climbing

  • Reinforcement learning

    Poker Q-learning leak finder

    Exploits opponent tendencies and finds leaks in my own play. 200k+ hands.

    +8 bb/100, simulated data only

  • RAG · Local LLMs

    arXiv Physics RAG

    Ask questions of physics papers with Ollama, ChromaDB and React.

    Public

  • Edge ML

    Model to Mask

    Taking neural networks and small language models to ASICs. A curiosity project.

    Public

  • Tooling

    WhatsApp bot remover

    Spots bots in group chats, deletes their messages and kicks them. Built for uni chats.

    Personal tool

Also on GitHub higgs-boson-classification electron-muon-scattering lstm-double-pendulum pca-mnist covid-19-predictor tenant-matchmaker-api

03

Stack

Platform and data
AWS, SageMaker, IAM, S3, Redshift, dbt, Iceberg, Kafka, PostgreSQL, Docker, HTCondor
ML and AI
PyTorch, TensorFlow, scikit-learn, transformers, GANs, LLMs, RAG, LLM evals, reinforcement learning
MLOps
MLflow, Weights & Biases, Git, CLI tooling, Dataiku (migrating away)
Languages
Python, SQL, JavaScript, React, Java, pandas, NumPy
Maths and physics
Statistics, item response theory, stochastic modelling, quantum information
Hardware-aware ML
FPGAs, HLS4ML, ONNX, pruning, quantisation, HPC
04

Outside work

  • Poker

    Former pro, then a dealer for a while. The statistics are what stuck.

  • Volleyball

    Ten years competitive, still in the London league. Two years as a volunteer coach, two promotions.

  • Reading

    AlphaSignal and TLDR to keep up. Standing opinion: DeepSeek is the GOAT, a Pareto legend.

  • Food

    My favourite hobby, by some distance. Hence the series below.

  • Games

    Chess, board games, video games, and FPL.

  • Outdoors

    Travelling and hiking, ideally towards somewhere good to eat.

A series

London lunch deals

Working through London's lunch deals one at a time. What is worth the walk, and what is a sad sandwich with a nice name.

  1. Coming soonThe first entries are on their way.
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Say hello

Happy to talk ML platforms, evals, physics, or where to get lunch.