About me

I am a fifth-year Ph.D. candidate in the Department of Electrical Engineering and Computer Science at UC Berkeley. I am fortunate to be advised by Professor Jiantao Jiao and Professor Stuart Russell. Previously, I graduated from Yao Class at Tsinghua University.

My research centers on understanding and improving the reasoning capabilities of large language models (LLMs). I approach this through theoretically analyzing their foundations and limitations, and designing more effective training, inference and evaluation methods. My work spans different regimes of reasoning, ranging from implicit reasoning, where models produce answers without explicit thinking steps (e.g., the reversal curse, two-hop reasoning, out-of-context reasoning), to inference-time reasoning with intermediate outputs (e.g., chain of continuous thought, token assorted), and up to agentic reasoning, where models proactively use tools and gather information to solve complex problems (e.g., GSM-Agent).

I’m also broadly interested in AI safety, model identifiability, decision-making and reinforcement learning, especially in how these areas intersect with the development and evaluation of more reliable, efficient, and interpretable AI systems.

I am on the academic job market in 2025-2026!

Selected papers (full publication list)

GSM-Agent: Understanding Agentic Reasoning Using Controllable Environments

Hanlin Zhu*, Tianyu Guo*, Song Mei, Stuart Russell, Nikhil Ghosh, Alberto Bietti, Jiantao Jiao

preprint, 2025

Emergence of Superposition: Unveiling the Training Dynamics of Chain of Continuous Thought

Hanlin Zhu, Shibo Hao, Zhiting Hu, Jiantao Jiao, Stuart Russell, Yuandong Tian

preprint, 2025

Reasoning by Superposition: A Theoretical Perspective on Chain of Continuous Thought [slides]

Hanlin Zhu*, Shibo Hao*, Zhiting Hu, Jiantao Jiao, Stuart Russell, Yuandong Tian

Conference on Neural Information Processing Systems (NeurIPS), 2025

Methods and Opportunities at Small Scale (MOSS) Workshop, ICML 2025 (Oral)

Generalization or Hallucination? Understanding Out-of-Context Reasoning in Transformers

Yixiao Huang*, Hanlin Zhu*, Tianyu Guo*, Jiantao Jiao, Somayeh Sojoudi, Michael I. Jordan, Stuart Russell, Song Mei

Conference on Neural Information Processing Systems (NeurIPS), 2025

Towards a Theoretical Understanding of the ‘Reversal Curse’ via Training Dynamics

Hanlin Zhu*, Baihe Huang*, Shaolun Zhang, Michael Jordan, Jiantao Jiao, Yuandong Tian, Stuart Russell

Conference on Neural Information Processing Systems (NeurIPS), 2024

On Representation Complexity of Model-based and Model-free Reinforcement Learning

Hanlin Zhu*, Baihe Huang*, Stuart Russell

International Conference on Learning Representations (ICLR), 2024

Importance Weighted Actor-Critic for Optimal Conservative Offline Reinforcement Learning

Hanlin Zhu, Paria Rashidinejad, Jiantao Jiao

Conference on Neural Information Processing Systems (NeurIPS), 2023