讲座题目： Propagation of quantum signal in plasmonic waveguides

报告人：任希锋 副教授

主持人：王鲁橹 讲师

时 间：2014年12月2日（周二）上午10：30-11：30

地 点：主楼1214

报告简介：

Quantum photonic integrated circuit (QPIC) based on dielectric waveguides has been widely used in linear optical quantum computation. Recently, surface plasmon was introduced to this area since it can confine and manipulate light beyond the diffraction limit. Here, on-chip quantum interference of two single surface plasmons is realized with dielectric loaded surface plasmon polariton waveguides. The high visibility larger than 90% not only proves the Bosonic nature of single plasmons, but also is feasible for realizing basic quantum logic gates in linear optical quantum computation. The effect of intrinsic losses in plasmonic waveguides on quantum information processing is also discussed. Even though the influence is negligible in this experiment, our studies reveal that loss can reduce the quantum interference visibility dramatically in some cases, which means quantum coherence must be carefully considered when designing QPIC devices.

We also demonstrate for the first time the maintaining of quantum polarization entanglement in a nanoscale hybrid plasmonic waveguide composed of a fiber taper and a silver nanowire. The transmitted state throughout the waveguide has a fidelity of 0.932 with the maximally polarization entangled state Φ+. Furthermore, the Clauser, Horne, Shimony, and Holt (CHSH) inequality test performed, resulting in value of 2:495±0:147 >2, demonstrates the violation of the hidden variable model. Since the plasmonic waveguide confines the effective mode area to subwavelength scale, it may be used as near-field quantum probe in a quantum near-field micro/nano-scope, which can realize high spatial resolution, ultra-sensitive, fiber-integrated, and plasmon-enhanced detection, as well as bridge nanophotonics and quantum optics.

报告人简介：

任希锋，中国科学技术大学副教授。分别于2001年和2006年在中国科学技术大学获得学士和博士学位，2006年至2006年在中国科学技术大学中国科学院量子信息实验室从事博士后研究，之后加入光学与光学工程系工作。2012年至2013年到美国普渡大学交流访问一年。2011年获教育部新世纪优秀人才称号。

任希锋副教授一直从事量子信息和表面等离子体光学的理论及实验研究，已经在国内外重要学术刊物上发表论文相关学术论文五十余篇，论文总引用四百余次。作为负责人承担过973课题，基金委面上等多个科研项目。目前主要从事量子集成光学芯片方面的研究，主要内容包括：1，量子表面等离子体光学，研究表面等离子体激元的量子效应，例如传输量子信号，作为光学天线改善单光子源性能等；2，量子集成光学芯片中的量子信息处理，例如新型集成光学器件的设计和加工，集成量子逻辑门的实现等。