Upcoming Talks:
I. Title: 基于“测量-重置”的量子比特复用的复杂性和形式化验证
Date: 2022年10月14日
Time: 9：30-10：30
摘要
量子比特数量是当前量子器件的主要局限之一，如何用尽可能少的量子比特完成相同的计算任务是一类重要的问题。这一报告中，我们重新探讨基于测量-重置的量子线路宽度优化方法，利用量子比特依赖图研究该线路优化问题的复杂性、启发式算法和形式化验证。
个人简介
蒋瀚如，BIMSA助理研究员。主要研究领域为程序设计语言、形式化方法和量子计算。
II. Title: 一般量子态生成和量子电路优化的复杂性刻画
Date: 2022.10.07
Time: 09:30-10:30
Venue: 清华大学近春园西楼1楼第1会议室 Seminar room 1 on the first floor of Jinchunyuan West Building at Tsinghua University
Zoom: 559 700 6085 （PW: BIMSA）
量子算法在通用数字量子计算机上的实现一般是通过标准量子电路。随着越来越多的量子比特集成，我们在不远的将来面临大量寿命有限的量子比特。如何利用这些量子比特完成尽可能多的量子电路是一个基本的问题。在这个报告中，我们汇报最近在一般量子态生成和量子电路的优化，在任意给定数量的辅助量子比特下，给出最优的量子电路。
Past 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）
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.
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.
