报告时间：11月22日 周四 下午4:00
报告题目： Tomography is necessary for universal entanglement detection with single-copy observable
Entanglement, one of the central mysteries of quantum mechanics, plays an essential role in numerous applications of quantum information theory. A natural question of both theoretical and experimental importance is whether universal entanglement detection is possible without full state tomography. In this work, we prove a no-go theorem that rules out this possibility for any non-adaptive schemes that employ single-copy measurements only. We also examine in detail a previously implemented experiment, which claimed to detect entanglement of two-qubit states via adaptive single-copy measurements without full state tomography. By performing the experiment and analyzing the data, we demonstrate that the information gathered is indeed sufficient to reconstruct the state. These results reveal a fundamental limit for single-copy measurements in entanglement detection, and provides a general framework to study the detection of other interesting properties of quantum states, such as the positivity of partial transpose and the k-symmetric extendibility.
俞能昆，悉尼科技大学高级讲师，分别于2008年和2013年于清华大学计算机科学与技术系取得本科和博士学位，主要研究方向为量子计算和量子信息。目前已经在ACM Symposium on Theory of Computing，Physical Review Letters，IEEE Transaction on Information Theory 等会议和期刊发表多篇论文。