Major obstacles against efficient long distance quantum communication are photon losses during transmission and the probabilistic nature of Bell measurement causing exponential scaling in time and resource with distance. To overcome these difficulties, while conventional quantum repeaters require matter-based operations with long-lived quantum memories, recent proposals have employed encoded multiple photons in entanglement, providing an alternative way for scalability. In pursuing scalable quantum communications, naturally arising questions are thus whether any ultimate limit exists in all-optical scalability, and whether and how it can be achieved. Motivated by these questions, we derive the fundamental limits of the efficiency and loss-tolerance of the Bell measurement with multiple photons, restricted not by protocols but by the laws of physics, i.e. linear optics and no-cloning theorem. We then propose a Bell measurement scheme with linear optics, which enables one to reach both the fundamental limits: one by linear optics and the other by the no-cloning theorem. The quantum repeater based on our scheme allows one to achieve fast and efficient quantum communication over arbitrary long distances, outperforming previous all-photonic and matter-based protocols. Our work provides a fundamental building block for quantum networks within but toward the ultimate limits of all-optical scalability.
Scalable iterative pruning of large language and vision models using block coordinate descent
Amazon Quantum Solutions Lab（亚马逊量子解决方案实验室）；AWS Center for Quantum Computing（AWS量子计算中心）；Fidelity Center for Applied Technology（富达应用技术中心）；AI Center of Excellence, FMR LLC（FMR LLC卓越人工智能中心）
Quantum Coulomb Blockade in Orbital Resolved Phosphorus Triple-Donor Molecule
Quantum / Nano-science and Technology Lab, Department of Physics, Indian Institute of Technology Roorkee（印度理工学院鲁尔基分校量子/纳米科学与技术实验室物理系）；Research Institute of Electronics, Shizuoka University（静冈大学电子研究所）；Centre of Nanotechnology, Indian Institute of Technology Roorkee（印度理工学院鲁尔基分校纳米技术中心）
A building block of quantum repeaters for scalable quantum networks
University of Science and Technology of China（中国科学技术大学）；Hefei National Research Center for Physical Sciences at the Microscale（合肥微尺度物质科学国家研究中心）；School of Physical Sciences, University of Science and Technology of China（中国科学技术大学物理学院）；Shanghai Research Center for Quantum Science（上海量子科学研究与创新中心）；CAS Center for Excellence in Quantum Information and Quantum Physics（中国科学院量子信息与量子物理学前沿卓越中心）；Hefei National Laboratory（合肥国家实验室）
