I am currently an AI research scientist at Meta GenAI Llama team. Previously, I was a postdoctoral associate at MIT CSAIL. I obtained my Ph.D and MS from Carnegie Mellon University, focusing on Machine Learning and statistics. My research was awarded the Qualcomm Innovation Fellowship (QIF 2022). Previously, I received my bachelor's from Fudan University.
I currently lead the reinforcement learning (RL) effort in Large Language Models (LLMs) post-training. My work centers on:
Most recent publications on Google Scholar.
MoDoMoDo: Multi-Domain Data Mixtures for Multimodal LLM Reinforcement Learning
Yiqing Liang, Jielin Qiu, Wenhao Ding, Zuxin Liu, James Tompkin, Mengdi Xu, Mengzhou Xia, Zhengzhong Tu, Laixi Shi, Jiacheng Zhu
arXiv preprint 2025
@misc{liang2025modomodo, title={MoDoMoDo: Multi-Domain Data Mixtures for Multimodal LLM Reinforcement Learning}, author={Yiqing Liang and Jielin Qiu and Wenhao Ding and Zuxin Liu and James Tompkin and Mengdi Xu and Mengzhou Xia and Zhengzhong Tu and Laixi Shi and Jiacheng Zhu}, year={2025}, eprint={2505.24871}, archivePrefix={arXiv}, primaryClass={cs.LG} }
Compress then Serve: Serving Thousands of LoRA Adapters with Little Overhead
Rickard Brüel Gabrielsson, Jiacheng Zhu, Onkar Bhardwaj, Leshem Choshen, Kristjan Greenewald, Mikhail Yurochkin, Justin Solomon
ICML 2025
@misc{brelgabrielsson2024compress, title={Compress then Serve: Serving Thousands of LoRA Adapters with Little Overhead}, author={Rickard Brüel-Gabrielsson and Jiacheng Zhu and Onkar Bhardwaj and Leshem Choshen and Kristjan Greenewald and Mikhail Yurochkin and Justin Solomon}, year={2025}, eprint={2407.00066}, archivePrefix={arXiv}, primaryClass={cs.DC} }
LLM Merging: Building LLMs Efficiently through Merging
Derek Tam, Margaret Li, Prateek Yadav, Rickard Brøel Gabrielsson, Jiacheng Zhu, Kristjan Greenewald, Mikhail Yurochkin, Mohit Bansal, Colin Raffel, Leshem Choshen
NeurIPS 2024 Competition
@inproceedings{tam2024llm, title={LLM Merging: Building LLMs Efficiently through Merging}, author={Derek Tam and Margaret Li and Prateek Yadav and Rickard Brøel Gabrielsson and Jiacheng Zhu and Kristjan Greenewald and Mikhail Yurochkin and Mohit Bansal and Colin Raffel and Leshem Choshen}, booktitle={Advances in Neural Information Processing Systems}, year={2024} }
MMSum: A Dataset for Multimodal Summarization and Thumbnail Generation of Videos
Jielin Qiu, Jiacheng Zhu, William Han, Aditesh Kumar, Karthik Mittal, Claire Jin, Zhengyuan Yang, Linjie Li, Jianfeng Wang, Ding Zhao, Bo Li, Lijuan Wang
CVPR 2024 Highlight
@inproceedings{qiu2024mmsum, title={MMSum: A Dataset for Multimodal Summarization and Thumbnail Generation of Videos}, author={Qiu, Jielin and Zhu, Jiacheng and Han, William and Kumar, Aditesh and Mittal, Karthik and Jin, Claire and Yang, Zhengyuan and Li, Linjie and Wang, Jianfeng and Zhao, Ding and others}, booktitle={Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition}, pages={21909--21921}, year={2024} }
Asymmetry in Low-Rank Adapters of Foundation Models
Jiacheng Zhu, Kristjan Greenewald, Kimia Nadjahi, Haitz Sáez de Ocáriz Borde, Rickard Brüel Gabrielsson, Leshem Choshen, Marzyeh Ghassemi, Mikhail Yurochkin, Justin Solomon
ICML 2024
@article{zhu2024asymmetry, title={Asymmetry in Low-Rank Adapters of Foundation Models}, author={Jiacheng Zhu and Kristjan Greenewald and Kimia Nadjahi and Haitz Sáez de Ocáriz Borde and Rickard Brüel Gabrielsson and Leshem Choshen and Marzyeh Ghassemi and Mikhail Yurochkin and Justin Solomon}, year={2024}, }
Functional optimal transport: map estimation and domain adaptation for functional data
Jiacheng Zhu*, Aritra Guha*, Dat Do*, Mengdi Xu, XuanLong Nguyen, Ding Zhao.
JMLR 2024
@article{zhu2024functional, title={Functional optimal transport: map estimation and domain adaptation for functional data}, author={Jiacheng Zhu and Aritra Guha and Dat Do and Mengdi Xu and XuanLong Nguyen and Ding Zhao}, journal={Journal of Machine Learning Research}, year={2024} }
Interpolation for Robust Learning: Data Augmentation on Wasserstein Geodesics
Jiacheng Zhu, Jielin Qiu, Aritra Guha, Zhuolin Yang, XuanLong Nguyen, Bo Li, Ding Zhao
ICML 2023
@InProceedings{pmlr-v202-zhu23i, title = {Interpolation for Robust Learning: Data Augmentation on {W}asserstein Geodesics}, author = {Zhu, Jiacheng and Qiu, Jielin and Guha, Aritra and Yang, Zhuolin and Nguyen, Xuanlong and Li, Bo and Zhao, Ding}, booktitle = {Proceedings of the 40th International Conference on Machine Learning}, pages = {43129--43157}, year = {2023}, editor = {Krause, Andreas and Brunskill, Emma and Cho, Kyunghyun and Engelhardt, Barbara and Sabato, Sivan and Scarlett, Jonathan}, volume = {202}, series = {Proceedings of Machine Learning Research}, month = {23--29 Jul}, publisher = {PMLR}, pdf = {https://proceedings.mlr.press/v202/zhu23i/zhu23i.pdf}, url = {https://proceedings.mlr.press/v202/zhu23i.html}, abstract = {We propose to study and promote the robustness of a model as per its performance on a continuous geodesic interpolation of subpopulations, e.g., a class of samples in a classification problem. Specifically, (1) we augment the data by finding the worst-case Wasserstein barycenter on the geodesic connecting subpopulation distributions. (2) we regularize the model for smoother performance on the continuous geodesic path connecting subpopulation distributions. (3) Additionally, we provide a theoretical guarantee of robustness improvement and investigate how the geodesic location and the sample size contribute, respectively. Experimental validations of the proposed strategy on four datasets including CIFAR-100 and ImageNet, establish the efficacy of our method, e.g., our method improves the baselines' certifiable robustness on CIFAR10 upto 7.7%, with 16.8% on empirical robustness on CIFAR-100. Our work provides a new perspective of model robustness through the lens of Wasserstein geodesic-based interpolation with a practical off-the-shelf strategy that can be combined with existing robust training methods.} }
Curriculum Reinforcement Learning using Optimal Transport via Gradual Domain Adaptation
Peide Huang, Mengdi Xu, Jiacheng Zhu, Laixi Shi, Ding Zhao
NeurIPS 2022
@inproceedings{ huang2022curriculum, title={Curriculum Reinforcement Learning using Optimal Transport via Gradual Domain Adaptation}, author={Peide Huang and Mengdi Xu and Jiacheng Zhu and Laixi Shi and Fei Fang and Ding Zhao}, booktitle={Advances in Neural Information Processing Systems}, editor={Alice H. Oh and Alekh Agarwal and Danielle Belgrave and Kyunghyun Cho}, year={2022}, url={https://openreview.net/forum?id=_cFdPHRLuJ} }
Task-Agnostic Online Reinforcement Learning with an Infinite Mixture of Gaussian Processes
Mengdi Xu, Wenhao Ding, Jiacheng Zhu, Zuxin Liu, Baiming Chen, Ding Zhao
NeurIPS 2020
@article{xu2020task, title={Task-agnostic online reinforcement learning with an infinite mixture of gaussian processes}, author={Xu, Mengdi and Ding, Wenhao and Zhu, Jiacheng and Liu, Zuxin and Chen, Baiming and Zhao, Ding}, journal={Advances in Neural Information Processing Systems}, volume={33}, pages={6429--6440}, year={2020} }
NeurIPS / ICLR / ICML / AISTATS(Top reviewer 2023) / AAAI / CHIL / MLHC / ML4H
Journal ReviewerTPAMI / TMLR / RA-L / IEEE T-ITS / IEEE T-IV