Speaker: 代昊博士，北京雁栖湖应用数学研究院

Title: Uncovering Non-Gaussianity through Multi-Copy Symmetries

Language: Chinese

Time & Venue: 2026.09.24 11:00-12:00 南楼N620

Abstract: Gaussian states are central to continuous-variable quantum information because they are experimentally accessible and fully characterized by first and second moments. However, non-Gaussianity is essential for universal quantum computation, yet difficult to detect due to the nonconvex structure of Gaussian set. We introduce a group-theoretic, multi-copy framework to detect non-Gaussianity. The key observation is that orthogonal copy-mixing operations commute with identical Gaussian unitaries, while displacements reduce the symmetry to transformations preserving a collective mode. This leads to exact expectation-value identities that all Gaussian states satisfy, and any violation certifies non-Gaussianity. The protocol is experimentally implementable using a threecopy Fourier tritter and photon-number-resolved detection, and it naturally extends to multimode systems.