报告时间：9月8日下午4点

报告地点：近代物理系210会议室

报告人： 南方科技大学 李俊副研究员

报告题目： Experimental Implementation of Design Hamiltonian Approach to Quantum Pseudorandomness on a 12-spin System

报告摘要：The ability of creating pseudorandom quantum states/operators is crucial in many quantum information processing schemes. However, Realizing pseudorandom operations in practice is getting more challenging with the growing size of near-term controllable quantum systems. Recently, [Phys. Rev. X 7, 021006 (2017)] proposed a promising new approach to quantum pseudorandomness, i.e., to generate random unitary operations out of random Hamiltonian evolutions. This method has much less resource requirements compared with previous generation protocols, and thus brings us much closer to developing experimental tools to investigate quantum (pseudo)randomness. In this talk, I will report our experimental implementation of this design Hamiltonian approach, using techniques of nuclear magnetic resonance (NMR).  I will show that how we managed to create an appropriately constructed random Hamiltonian for producing highly random evolutions on a 12-spin NMR system. In our 12-spin molecule, to generate random dynamics over the system's vast degrees of freedom is a nontrivial task. We then used multiple-quantum techniques to measure spreading of quantum coherences, and so to probe the growth of quantum pseudorandomness. The measured multiple-quantum coherence spectra indicate that substantial quantum pseudorandomness have been achieved.

报告人简介：Jun Li obtained his Ph.D in physics at the University of Science and Technology of China, under the supervision of Prof. Xinhua Peng. After graduating in 2015, he first joined Beijing Computational Science Research Center and then visited Institute for Quantum Computing, University of Waterloo, Canada as a postdoctoral fellow. He is presently an associate research fellow in Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen. His research interests include quantum control, quantum simulation and nuclear magnetic resonance experiments, with particular emphasis on studying of complex dynamics behaviors that occur in spin systems, and developing of scalable approaches towards large-sized quantum system control.