An international, multi-institution effort has shown a significant speed-up in using quantum learning techniques to characterize physical systems. The researchers showed that while a classical, entanglement-free approach to these measurements would take 20 million years, their quantum, entanglement-enhanced approach took less than 15 minutes. Quantum learning advantage on a scalable photonic platform, appearing in Science, describes that by harnessing the unique quantum phenomenon of entanglement, they directly probed the properties of a quantum system in a way not possible with classical techniques.
“Quantum science has reached an extraordinary stage, where theorists can dream up a scheme for exploiting quantum entanglement to perform measurements that would otherwise be impossible, and a heroic team of experimentalists can swiftly turn that dream into reality,” John Preskill, a co-author on the paper.
This work represents a broad collaboration, demonstrating connections between Caltech researchers and alums along with international collaborators. The project began in 2022 between John Preskill and Liang Jiang (Caltech undergrad, returned as a Burke Postdoctoral Scholar, now faculty at University of Chicago) based on ideas from Hsin-Yuan (Robert) Huang (Caltech grad student, now PMA faculty). A theory paper Entanglement-Enabled Advantage for Learning a Bosonic Random Displacement Channel proposing an experiment was published in 2024.
The Science paper describes the successful execution of the experiment by Ulrik Andersen’s group at the Technical University of Denmark. The theory and experiment combined show that quantum entanglement provides an enormous advantage in learning properties of a process that applies phase space displacements to many photonic modes.
Additional Caltech authors on the paper include Sisi Zhou (former Postdoc, now faculty at Perimeter Institute) and Senrui Chen (former University of Chicago grad student, currently an IQIM Postdoc).
Find more info and the full papers:
Zheng-Hao Liu, Romain Brunel, Emil E. B. Østergaard, Oscar Cordero, Senrui Chen, Yat Wong, Jens A. H. Nielsen, Axel B. Bregnsbo, Sisi Zhou, Hsin-Yuan Huang, Changhun Oh, Liang Jiang, John Preskill, Jonas S. Neergaard-Nielsen, Ulrik L. Andersen, Quantum learning advantage on a scalable photonic platform, Science, 25 Sep 2025.
Changhun Oh, Senrui Chen, Yat Wong, Sisi Zhou, Hsin-Yuan Huang, Jens A.H. Nielsen, Zheng-Hao Liu, Jonas S. Neergaard-Nielsen, Ulrik L. Andersen, Liang Jiang, John Preskill. Entanglement-enabled advantage for learning a bosonic random displacement channel, Phys. Rev. Lett. 133, 230604 (2024).
The Science paper was also featured by:
University of Chicago: Multi-institution collaboration achieves quantum advantage in probing quantum systems
Technical University of Denmark: Proven quantum advantage: Researchers cut the time for a learning task from 20 million years to 15 minutes
Perimeter Institute: New experiment shows quantum advantage in learning about physical systems
