报告时间：7月9日上午10点半

报告地点：近代物理系210会议室

报告人： 新加坡南洋理工大学 顾麦然教授

报告题目：Quantum Plug n' Play: Modular Computation in a Quantum World

报告摘要：When Google upgrades their hardware, applications that make use of Google services continue to operate without needing an update. This modular architecture plays an essential role in modern technology. It allows a client, Alice, to make use of computations done on a remote server, without knowing any details regarding how this computation was made. This modularity is enabled by an interface – an established set of rules that specifies how Alice delivers input to the server, and how the server returns relevant output to Alice. Once agreed, Alice can design technology that makes use of the server's functions as subroutines, while remaining completely ignorant on how the server implements such functions. Such interfaces are now industry standard. Known as APIs (application program interface), their adoption is almost universal – from specifying how we interface with graphics cards to the IBM quantum computer.

So far, all such interfaces assume information exchanged between server and client goes through classical channels, limiting the scope of collaborative quantum computing. What happens when these interfaces allow Alice to exchange quantum systems with the server?

In this presentation, I will introduce a way to formalize modular quantum computing in the quantum regime. I discuss conditions where this modularity is unattainable and how such constraints can affect many existing quantum algorithms. I then describe how this formalism can guide us in developing new algorithms that do admit modular designs. I show how this methodology leads to two new quantum algorithms -- modular DQC1 and modular factoring. The former can evaluate the normalized modulus of the trace of a completely unknown unitary process, the latter can perform the full functionality of factoring with a polynomial reduction in the number of elementary gates over standard quantum algorithms.

Reference: New Journal of Physics 20.1 013004 (2018)

报告人简介：Mile Gu is a National Research Foundation Fellow, and holds dual positions the Complexity Institute at Nanyang Technological University and the Centre for Quantum Technologies. He currently heads the quantum and complexity science initiative - which explores how quantum technologies can help us understand the science of complex systems (www.quantumcomplexity.org). Gu has made significant contributions to the interface of quantum and complexity science, including five in various Nature/Science suite journals, and 9 in a combination of Physical Review Letters and Physical Review X. Prior to his current appointment, Gu obtained his Ph.D. at the University of Queensland, and spent 3 years conducting research at the Institute for Interdisciplinary Information Sciences Tsinghua University under the China Thousand Talents Program.