【报告题目一】Quantum clock synchronization without synchronized clocks
【报告人】Tim Byrnes 教授，New York University (NY)
【时间】5月10日（星期五）上午 9: 00-10:00
A major outstanding problem for many quantum clock synchronization protocols is the hidden assumption of a common phase reference between the parties to be synchronized. In general, the definition of the quantum states between two parties do not have consistent phase definitions, which can lead to an unknown systematic error. We show that despite prior arguments to the contrary, it is possible to remove this unknown phase via entanglement purification. This closes the loophole for entanglement based quantum clock synchronization protocols, which is a non-local approach to synchronize two clocks independent of the properties of the intervening medium. Starting with noisy Bell pairs, we show that the scheme produces a singlet state for any combination of (i) differing basis conventions for Alice and Bob; (ii) an overall time offset in the execution of the purification algorithm; and (iii) the presence of a noisy channel. Error estimates reveal that better performance than existing classical Einstein synchronization protocols should be achievable using current technology.
 Ebubechukwu O. Ilo-Okeke, Louis Tessler, Jonathan P. Dowling and Tim Byrnes, npj Quantum Information 4, 40 (2018).
 R. Jozsa, D. S. Abrams, J. P. Dowling, and C. P. Williams, Phys. Rev. Lett. 85, 2010 (2000).
【编辑概况】Tim Byrnes is Assistant Professor of Physics at NYU Shanghai. He is also Visiting Assistant Professor at the National Institute of Informatics in Tokyo, Japan. He holds a PhD from the University of New South Wales in Sydney, Australia.
Professor Byrnes' research interests are in quantum information technologies, condensed matter physics, and AMO (atomic, molecular, optical) physics. Specifically, he is interested in various applications of Bose-Einstein condensates to quantum information. He is also interested in the interface of physics and biology and emergent phenomena.
Tim Byrnes completed his Ph.D. at the University of New South Wales in Sydney, Australia in the fields of condensed matter physics and high energy physics under the supervision of Prof. Chris Hamer. During this time he worked on applications of DMRG (Density Matrix Renomalization Group), a powerful method for solving 1D quantum many-body problems, to lattice gauge theories. He then moved to Tokyo, Japan to commence a postdoctoral fellowship with Prof. Yoshihisa Yamamoto in the field of quantum information at the National Institute of Informatics and the University of Tokyo. There he worked on topics related to quantum simulation, such as methods of solving lattice gauge theories on a quantum computer, and semiconductor implementations of a quantum simulator. He has worked on the theory of Bose-Einstein condensation in exciton-polariton systems, such as the BEC-BCS crossover and applications to the generation of non-classical light.
He is now Assistant Professor at NYU Shanghai, where he examines Bose-Einstein condensates for various applications in quantum information technology.
【报告题目二】Nature vs. Nurture in Complex (and Not-So-Complex) Systems
【报告人】Daniel Stein 教授，New York University Shanghai
【时间】5月10日（星期五）上午 10: 00-11:00
Understanding the dynamical behavior of many-particle systems following a deep quench is a central issue in both statistical mechanics and complex systems theory. One of the basic questions centers on the issue of predictability: given a system with a random initial state evolving through a well-defined stochastic dynamics, how much of the information contained in the state at future times depends on the initial condition (``nature'') and how much on the dynamical realization (``nurture'')? We discuss this question and present both old and new results for both homogeneous and random systems in low and high dimension.
【编辑概况】Daniel L. Stein is Professor of Physics and Mathematics at New York University. From 2006-2012 he served as NYU Dean of Science. Prior to coming to NYU, he served on the faculties at Princeton University and at the University of Arizona, where he was Head of the Department of Physics for a decade. He received his Ph.D. In Physics from Princeton University in 1979.
His research is in the fields of theoretical condensed matter physics, statistical mechanics, and biological physics. It focuses primarily on randomness and disorder in condensed matter systems, with an emphasis on magnetic materials and on stochastic processes leading to rare nucleation events. In addition, he has worked on topics as diverse as protein biophysics, biological evolution, amorphous semiconductors, superconductors and superfluids, liquid crystals, neutron stars, and the interface between particle physics and cosmology.
His awards include a Princeton University C.E. Proctor Fellowship, an Alfred P. Sloan Fellowship, University of Arizona College of Science Distinguished Teaching Award, Commission on the Status of Women Vision 2000 Award, election as a Fellow of the American Physical Society, election as a Fellow of the American Association for the Advancement of Science, the U.S. Air Force Exemplary Civilian Service Medal, and a John Simon Guggenheim Foundation Fellows.