Zixuan Zhang

Zixuan Zhang

Anthropic Research Fellow · AI Security · Agentic RL · Learning Theory

I'm a final-year Ph.D. student in the H. Milton Stewart School of Industrial and Systems Engineering (ISyE) at Georgia Tech, advised by Prof. Tuo Zhao, and currently a Research Fellow in the Anthropic Fellows Program.

My research aims to make large-scale AI systems reliable and interpretable: quantitative threat models for AI safety and security; large-scale RL post-training for LLM agents, from environment infrastructure to training that stays efficient and stable over long horizons; and statistical and optimization theory of diffusion models and deep networks.

Portrait of Zixuan Zhang

01Research

Exfiltration scaling lawDrag ↔
Pretraining short medium long
Safety & Security

Quantitative threat models

Measuring how well safeguards hold up against realistic attacks, such as weight exfiltration under egress limits.

Current project ↓
Decoupled agentic RL
Rollouts busy –Sync · stages take turns
Agents & Environments

Environments for agents

Environments, sandboxes, and rollout infra that keep LLM serving, agent rollouts, and training decoupled.

strands-env ↗
Stable vs. unstable RL
RL & Reward

Stable RL, robust rewards

Long-horizon RL that stays stable, and reward and oversight signals that hold up under optimization.

Related papers ↓
Reverse diffusion onto a manifoldNoise
Theory

Guarantees for modern models

Statistical and optimization guarantees for LLMs and diffusion models.

Related papers ↓

02Experience

Anthropic Fellows Program

Aug 2026 – now
Research Fellow

How well do egress limits protect model weights from exfiltration?

3,000+compress-then-retrain attacks
dense + MoEtarget model ladders
  • Threat model: compute an attacker recovers under egress and retraining budgets.
  • Agent swarm that proposes and runs attacks in byte/FLOP-metered sandboxes.
  • Interpretable scaling laws for the required egress limit. Paper in prep.

Amazon · Stores Foundational AI (Rufus)

Jan – Jul 2026
Applied Scientist Intern

Agent RL post-training on a 100B+ MoE base.

3,000+concurrent rollouts
+7.8MCP-Atlas
+9.8Tau2-Retail
  • Led agent RL for tool use and terminal coding; decoupled rollouts via strands-env.
  • Steered recipe and infra from reward, rollout, and KL/entropy diagnostics.
  • Built MCP, user-sim, and terminal environments plus a sandbox service on AWS EKS.

Microsoft Research

Jun 2024 – Jun 2025
Research Scientist Intern

Memory-efficient LLM optimization and structured MoE compression.

03Publications

Full list on Google Scholar

04Talks

  • 2025 A Minimalist Example of Edge-of-Stability and Progressive Sharpening INFORMS Applied Probability Society Conference, Atlanta Slides
  • 2025 Robust Reinforcement Learning from Corrupted Human Feedback International Conference on Continuous Optimization (ICCOPT), Los Angeles Slides
  • 2024 Sample Complexity of Diffusion Models for Learning Distributions on Low Dimensional Manifolds INFORMS Annual Meeting, Seattle Slides

05Education

  • Georgia Institute of TechnologyPh.D. in Machine Learning · Advisor: Tuo Zhao
    2022 – now
  • University of Science and Technology of ChinaB.S. in Statistics
    2018 – 2022
Honors
  • 2025Alice and John Jarvis Paper Award, Georgia Tech
  • 2024NeurIPS Travel Grant
  • 2022Stewart Topper Fellowship, Georgia Tech
Teaching
  • Summer 2025Basic Statistical Methods (ISYE 3030)Instructor
  • Fall 2023Computational Data Analysis (CSE/ISYE 6740)Teaching Assistant
  • Summer 2023Probability with Applications (ISYE 2027)Teaching Assistant