From game78518 at gmail.com Tue Feb 14 13:40:28 2017 From: game78518 at gmail.com (=?UTF-8?B?5rSq55Cu55yp?=) Date: Tue, 14 Feb 2017 13:40:28 +0800 Subject: [Theory-Talk] [Talk] 2017/02/15 Round Complexity in the Local Transformations of Quantum and Classical States Message-ID: *Topic?*Round Complexity in the Local Transformations of Quantum and Classical States *Speaker?*Prof. Min-Hsiu Hsieh (University of Technology Sydney) *Location?*Auditorium 106 at IIS new Building *Date?* 2017-02-15 (Wed) 14:00 ? 16:00 *Abstract:* A natural operational paradigm for distributed quantum and classical information processing involves local operations coordinated by multiple rounds of public communication. In this paper we consider the minimum number of communication rounds needed to perform the locality-constrained task of entanglement transformation and the analogous classical task of secrecy manipulation. Specifically we address whether bipartite mixed entanglement can always be converted into pure entanglement or whether unsecure classical correlations can always be transformed into secret shared randomness using local operations and a bounded number of communication exchanges. Our main contribution in this paper is an explicit construction of quantum and classical state transformations which, for any given r, can be achieved using r rounds of classical communication exchanges but no fewer. Our results reveal that highly complex communication protocols are indeed necessary to fully harness the information-theoretic resources contained in general quantum and classical states. The major technical contribution of this manuscript lies in proving lower bounds for the required number of communication exchanges using the notion of common information and various lemmas built upon it. We propose a classical analog to the Schmidt rank of a bipartite quantum state which we call the secrecy rank, and we show that it is a monotone under stochastic local classical operations. This is a joint work with Eric Chitambar. -------------- next part -------------- An HTML attachment was scrubbed... URL: From game78518 at gmail.com Tue Feb 14 19:29:37 2017 From: game78518 at gmail.com (=?UTF-8?B?5rSq55Cu55yp?=) Date: Tue, 14 Feb 2017 19:29:37 +0800 Subject: [Theory-Talk] [Talk] 2017/02/15 From Quantumness to Security Message-ID: Topic: From Quantumness to Security Speaker: Prof. Xiong-Feng Ma (Institute for Interdisciplinary Information Sciences) Date: 2017-02-15 (Wed) 16:00 ? 17:20 Location: Auditorium 106 at IIS new Building Host: Kai-Min Chung *Abstract:* Coherence and entanglement are two peculiar features of quantum theory. Coherence captures the phenomenon of coherent superposition of quantum states, while entanglement, ?the spooky action at a distance?, plays a crucial role in the nonlocality of quantum mechanics. In this talk, I shall present two links: between coherence and randomness in quantum random number generation, and between entanglement and security in quantum key distribution. Random numbers play an indispensable role in modern society in various arenas of finance, cryptography, and computation. Considering individual and coherent measurement of the correlated party, we show that the coherence of formation and the relative entropy of coherence measure the quantum randomness for these two situations, respectively. Furthermore, we calculate the gap between the two quantum randomness, which turns out to related another quantum correlation --- discord. In quantum information processing, entanglement becomes an important resource for various tasks, such as teleportation, quantum computation, and cryptography. Intuitively, entanglement means a strong nonlocal correlation between distant parties, which essentially offers a secure key generation tool. Various Bell?s inequality test experiments have proved that eavesdropping (as a local hidden variable) can be fundamentally ruled out. In this talk, I shall link the basic concept of entanglement with the security of key distribution. *BIO:* Xiongfeng Ma?s main research interest lies on quantum information and quantum optics, particularly in quantum cryptography and correlation. After obtaining his BSc at Peking University in 2003, Xiongfeng attended the University of Toronto for his PhD degree. From 2008 to 2011, he did his post-doc and visiting positions at the University of Waterloo, the University of Toronto, and the University of Leeds. In 2012, Xiongfeng joined Tsinghua University as an assistant professor. -------------- next part -------------- An HTML attachment was scrubbed... URL: