I'm Junjie 俊杰.
CS + Maths @ UC Berkeley
My research centers on reinforcement learning, training language model agents, continual learning, and LLM evaluation.
More broadly, I am interested in language models and machine learning systems, and I am currently deepening my understanding of efficient inference.
Outside of research, I am drawn to investing and the venture capital world, and I am an avid reader. I also enjoy staying active through swimming, long-distance running, and racket sports like tennis, squash, and pickleball.
Currently
I am looking for roles in post-training research, machine learning engineering (MLE), and software engineering (SWE).
Research
RL for language models and agents; advised by Raluca Ada Popa & Ion Stoica.
I am forever thankful for the mentoring from Sijun Tan, Tianhao Wu, and Sida Li.
NLP Group; advised by Dan Jurafsky and mentored by Chen Shani, exploring whether post-training can steer language models toward concept-preserving reasoning.
Contributed to the Vulci project with Maurizio Forte, doing geophysical surveys and computer graphics; mentored by Nevio Danelon and Antonio Lopiano.
Internships
Built an evaluation harness for math reasoning that uses an automated Lean prover to auto-formalize natural-language math into Lean and machine-check the resulting proofs, enabling scalable, rigorous grading of model outputs.
First-authored "Towards Expert Financial QA via Self-Improving RAG" (AFA Workshop @ ICLR 2026).
Two rotations:
1) AI Product, building a Plaud-style voice-memory product with a memory layer over Mem0, Zep, and Letta, and audio-language models for detection and evaluation;
2) AI Infra on Xiaomi MiMo, the company's large language model lab, building pretraining data pipelines (deduplication and quality filtering) and internal tooling for data QA, validation, and dataset access.
Supported deal sourcing and due diligence for early-stage consumer investments, including Tea'stone, Pop Mart, Chi Forest, and Qiandama. Cowin is a private equity and venture capital firm founded in 2000, with about US$4.7 billion in AUM.