Jiachen Sun

Cartoon avatar illustration

Hi 👋, I'm a senior machine learning scientist at LinkedIn's Core AI team (Dec 2024 – present). My work centers on large language models, agentic reinforcement learning, fine‑tuning and benchmarking. I'm broadly interested in computer vision, vision–language models, and adversarial & trustworthy ML for real‑world LLM applications.

I earned my Ph.D. in Computer Science & Engineering at the University of Michigan, advised by Prof. Z. Morley Mao. Prior to that, I received a B.S.E. in Information Engineering from Shanghai Jiao Tong University (graduated with honor, top 5%) and studied at the University of Washington.

You can reach me at jcsun0806@gmail.com. This webpage was 99.9% generated by agentic AI.

Research

I love building reliable and efficient machine‑learning systems that can be deployed in the wild. My work spans from pre- and post-training large language models to designing multimodal perception systems for autonomous vehicles and robotics. I’m particularly excited about:

  • Large Language Models & Agents: I am currently focusing on agentic reinforcement learning for LinkedIn flagship applications.
  • Vision–Language Models: building VLM agents and hardening them against visual prompt injection.
  • MultiModal Perception: fusing camera, LiDAR and other sensors for robust 3D understanding and collaborative vehicular perception.
  • Adversarial & Trustworthy ML: certified robustness and adversarial attacks/defenses for real-world deep learning models.

What's New

[2025.01]
🎉 Two papers accepted at ICLR 2025: Label‑Free Coreset Selection with Proxy Training Dynamics and Cocoon: Robust Multi‑Modal Perception with Uncertainty‑Aware Sensor Fusion.
[2024.11]
🚗 Our collaborative perception work Boosting Collaborative Vehicular Perception on the Edge with Vehicle‑to‑Vehicle Communication was accepted at ACM SenSys 2024.
[2024.07]
🌍 Our multimodal driving assistant Dolphins: Multimodal Language Model for Driving has been accepted to ECCV 2024.
[2024.12]
💼 After a year as a machine learning scientist at TikTok, I joined LinkedIn’s Core AI team.
[2023.10-12]
🎓 I completed my Ph.D. in Computer Science & Engineering at the University of Michigan and started working at TikTok.

Honors & Awards

2024

Spotlight Bonus & Outstanding Employee Award, TikTok

2023

Rackham Student Travel Grant

2022

SRML Workshop Best Paper Award

2020

ACM MobiCom & MobiSys Travel Grant (Virtual)

2017–2018

Outstanding Research Scholarship of SJTU (top 1%)

2017

Outstanding Winner & INFORMS Award in Mathematical Contest in Modeling

2016–2017

Academic Excellence Scholarship of SJTU, A Class (top 1%)

2014–2016

Academic & Honor Scholarships of Zhiyuan College and SJTU

Selected Publications

See full list at Google Scholar.

ICLR 2025
ELFS illustration

Label‑Free Coreset Selection with Proxy Training Dynamics

H. Zheng, E. Tsai, Y. Lu, Jiachen Sun, B. R. Bartoldson, B. Kailkhura, A. Prakash

In Proceedings of ICLR 2025 (Acceptance Rate 32.0%)

ICLR 2025
Cocoon illustration

Cocoon: Robust Multi‑Modal Perception with Uncertainty‑Aware Sensor Fusion

M. Cho, Y. Cao, Jiachen Sun, Q. Zhang, M. Pavone, J. J. Park, H. Yang, Z. Mao

In Proceedings of ICLR 2025 (Acceptance Rate 32.0%)

USENIX Security 2024
Data fabrication illustration

On Data Fabrication in Collaborative Vehicular Perception: Attacks and Countermeasures

Q. Zhang, S. Jin, Jiachen Sun, R. Zhu, X. Zhang, Q. Chen, Z. Mao

In Proceedings of USENIX Security 2024

ECCV 2024
Hierarchical memory network illustration

Data Condensation with Hierarchical Memory Network

H. Zheng, Jiachen Sun, C. Xiao, Z. Mao, A. Prakash

In Proceedings of ECCV 2024

ECCV 2024
Dolphins illustration

Dolphins: Multimodal Language Model for Driving

Y. Ma, Y. Cao, Jiachen Sun, M. Pavone, C. Xiao

In Proceedings of ECCV 2024 (Acceptance Rate 27.9%)

SenSys 2024
Collaborative vehicular perception illustration

Boosting Collaborative Vehicular Perception on the Edge with Vehicle‑to‑Vehicle Communication

R. Zhu, X. Zhu, A. Zhang, X. Zhang, Jiachen Sun, F. Qian, H. Qiu, Z. Mao, M. Lee

In Proceedings of ACM SenSys 2024

arXiv 2024
SmoothVLM illustration

SmoothVLM: Safeguarding Vision–Language Models Against Patched Visual Prompt Injectors

Jiachen Sun, C. Wang, Y. Zhang, C. Xiao

arXiv preprint arXiv:2405.10529 (2024)

ICLR 2024
CALICO illustration

CALICO: Self‑Supervised Camera–LiDAR Contrastive Pre‑training for BEV Perception

Jiachen Sun, H. Zheng, Q. Zhang, A. Prakash, Z. Mao, C. Xiao

In Proceedings of ICLR 2024 (Acceptance Rate 26.0%)

ACM MM 2023
VPA illustration

VPA: Fully Test‑Time Visual Prompt Adaptation

Jiachen Sun, M. Ibrahim, M. Hall, I. Evtimov, Z. Mao, C. Ferrer, C. Hazirbas

In Proceedings of ACM MultiMedia 2023 (Acceptance Rate 29.2%)

ICML 2023
Diffusion purification illustration

A Critical Revisit of Adversarial Robustness in 3D Point Cloud Recognition with Diffusion‑Driven Purification

Jiachen Sun, J. Wang, W. Nie, Z. Yu, Z. Mao, C. Xiao

In Proceedings of ICML 2023 (Acceptance Rate 27.9%)

CVPR 2022
Trajectory robustness illustration

On Adversarial Robustness of Trajectory Prediction for Autonomous Vehicles

Q. Zhang, S. Hu, Jiachen Sun, Q. Chen, Z. Mao

In Proceedings of CVPR 2022 (Acceptance Rate 25.3%)

ECCV 2022
Spectral smoothing illustration

A Spectral View of Randomized Smoothing under Common Corruptions: Benchmarking and Improving Certified Robustness

Jiachen Sun, A. Mehra, B. Kailkhura, P. Chen, D. Hendrycks, J. Hamm, Z. Mao

In Proceedings of ECCV 2022 (Acceptance Rate 28.0%)

NeurIPS 2021
Self-supervision 3D illustration

Adversarially Robust 3D Point Cloud Recognition Using Self‑Supervisions

Jiachen Sun, Y. Cao, C. Choy, Z. Yu, A. Anandkumar, Z. Mao, C. Xiao

In Proceedings of NeurIPS 2021 (Acceptance Rate 26.0%)

BMVC 2021
DeepSym illustration

On Adversarial Robustness of 3D Point Cloud Classification under Adaptive Attacks

Jiachen Sun, K. Koenig, Y. Cao, Q. Chen, Z. Mao

In Proceedings of BMVC 2021 (Acceptance Rate 35.9%)

MobiCom 2021
Edge-assisted multi-vehicle perception illustration

EMP: Edge‑Assisted Multi‑Vehicle Perception

X. Zhang, A. Zhang, Jiachen Sun, X. Zhu, Y. Guo, Q. Feng, Z. Mao

In Proceedings of ACM MobiCom 2021 (Acceptance Rate 20.0%)

USENIX Security 2021
DOS vulnerabilities illustration

Automatic Discovery of Denial‑of‑Service Vulnerabilities in Connected Vehicle Network Stack

S. Hu, Q. Chen, Jiachen Sun, Y. Feng, Z. Mao, H. Liu

In Proceedings of USENIX Security 2021 (Acceptance Rate 19.0%)

USENIX Security 2020
LiDAR attack illustration

Towards Robust LiDAR‑based Perception in Autonomous Driving: General Black‑box Adversarial Sensor Attack and Countermeasures

Jiachen Sun, Y. Cao, Q. Chen, Z. Mao

In Proceedings of USENIX Security 2020 (Acceptance Rate 13.3%)

MobiSys 2020
MPBond illustration

MPBond: Efficient Network‑Level Collaboration Among Personal Mobile Devices

X. Zhu, Jiachen Sun, X. Zhang, Y. Guo, F. Qian, Z. Mao

In Proceedings of ACM MobiSys 2020 (Acceptance Rate 19.4%)

INFOCOM 2019
Anomaly detection illustration

Detecting Anomaly in Large‑Scale Network Using Mobile Crowdsourcing

Y. Li, Jiachen Sun, W. Huang, X. Tian

In Proceedings of IEEE INFOCOM 2019 (Acceptance Rate 19.7%)

MobiCom 2018
Ghostbuster illustration

Ghostbuster: Detecting the Presence of Hidden Eavesdroppers

A. Chaman, J. Wang, Jiachen Sun, H. Hassanieh, R. Choudhury

In Proceedings of ACM MobiCom 2018 (Acceptance Rate 22.4%)