Quantum Information Seminar量子信息讨论班

Organizer:Zhengwei Liu 刘正伟(BIMSA&Tsinghua University)
Time:09:30-12:15 Fri. 2022.09.23
Venue:559 700 6085 (PW: BIMSA);JCY-1

Upcoming Talks:

        Title: Fundamental Limitation on the Detectability of Entanglement


Speaker:    Zhenhuan Liu


Date:    2022.09.23

Time:    09:30-12:15

Venue: JCY-1

Zoom:    559 700 6085   (PW: BIMSA


Abstract:  

Entanglement detection is essential in quantum information science and quantum many-body physics. It has been proved that entanglement exists almost surely for a random quantum state, while the realizations of effective entanglement criteria usually consume exponential resources, and efficient criteria often perform poorly without prior knowledge. This fact implies a fundamental limitation might exist in the detectability of entanglement. In this work, we formalize this limitation as a fundamental trade-off between the efficiency and effectiveness of entanglement criteria via a systematic method to theoretically evaluate the detection capability of entanglement criteria. For a system coupled to an environment, we prove that any entanglement criterion needs exponentially many observables to detect the entanglement effectively when restricted to single-copy operations. Otherwise, the detection capability of the criterion will decay double-exponentially. Furthermore, if multi-copy joint measurements are allowed, the effectiveness of entanglement detection can be exponentially improved, which implies a quantum advantage in entanglement detection problems.
(Ref: Pengyu Liu, Zhenhuan Liu, Shu Chen, Xiongfeng Ma. arXiv:2208.02518)


Speaker Intro:

Zhenhuan Liu is a PhD candidate in the Institute for Interdisciplinary Information Science, Tsinghua University. He got his bachelor’s degree from the School of Physics, Peking University, in 2020 and started doctoral research on quantum information science. His research interests include quantum foundation, entanglement detection, and quantum system benchmarking.





Past talks:


Title:Quantum soundness of the tensor code test

Speaker: Zhengfeng Ji 季铮锋(Tsinghua University)

Abstract摘要:

Tensor codes provide a simple family of combinatorial constructions of locally testable codes that generalize the family of Reed-Muller codes. The natural test for tensor codes, the axis-parallel line vs. point test, plays an essential role in constructions of probabilistically checkable proofs. The quantum soundness of tensor code test is an essential component of the MIP* = RE theorem as it naturally generalize the low indivitual degree test. In this talk, we will discuss the proof ideas behind the quantum soundness analysis, its use in the MIP* = RE proof, and several interesting related open problems.

Profile简介:

Zhengfeng Ji is currently a professor in the Department of Computer Science and Technology, Tsinghua University. His research studies quantum computing from a computer science perspective, recently focusing on the quantum algorithm and complexity theory, quantum cryptography, and quantum software.