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 (Feb 12 2025).

Abstract: Recent advancements in quantum technologies have opened new horizons for exploring the physical world in ways once deemed impossible. Central to these breakthroughs is the concept of quantum advantage, where quantum systems outperform their classical counterparts in solving specific tasks. While much attention has been devoted to computational speedups, quantum advantage in learning physical systems remains a largely untapped frontier. Here, we present a photonic implementation of a quantum-enhanced protocol for learning the probability distribution of a multimode bosonic displacement process. By harnessing the unique properties of continuous-variable quantum entanglement, we obtain a massive advantage in sample complexity with respect to conventional methods without entangled resources. With approximately 5 dB of two-mode squeezing -- corresponding to imperfect Einstein--Podolsky--Rosen (EPR) entanglement -- we learn a 100-mode bosonic displacement process using 11.8 orders of magnitude fewer samples than a conventional scheme. Our results demonstrate that even with non-ideal, noisy entanglement, a significant quantum advantage can be realized in continuous-variable quantum systems. This marks an important step towards practical quantum-enhanced learning protocols with implications for quantum metrology, certification, and machine learning.

Arxiv: https://arxiv.org/abs/2502.07770