Dimitri Kusnezov (The Hon. Dr.) is an American theoretical physicist and university professor who served as the fifth Under Secretary for Science and Technology at the U.S. Department of Homeland Security (2022–2025) and as the first Deputy Under Secretary for Artificial Intelligence and Technology at the U.S. Department of Energy (2018–2020). Through six administrations, he led large S&T organizations supporting high consequence, mission-critical decisions across U.S. nuclear weapons and national security, open science, law enforcement, and emergency management. His work emphasized emerging technologies—including AI, quantum, biosecurity, autonomous systems, and high-performance computing—translating first-of-kind capabilities from research into real-world operations. He has published 160+ papers and articles and edited two books, and has extensive experience managing the risks that come with high-hazard efforts where mistakes carry real operational and reputational consequences. Kusnezov began his career as a professor of theoretical physics at Yale University, working in quantum many-body theory and complex systems, having received his PhD and MA degrees from Princeton University in theoretical physics and AB degrees with highest honors in Physics and in Pure Mathematics from UC Berkeley.

With over a decade of experience in semiconductor physics and circuit design, he led an R&D team for quantum tech for 5 years at a Fortune 500 company. His work spans algorithm development for quantum machine learning and quantum CAE. He bridges technology and business to support the adoption and social implementation of advanced technologies, while also leading global collaboration projects with US quantum HW vender. Since 2020, he has served as a collaborative researcher at the Quantum Computing Center, Keio University, and currently also serves as a visiting researcher at AIST G-QuAT. He holds a Ph.D. in Engineering.