When chiral light meets chiral matter: optical nonreciprocity and isolation （当手性光遇上手性物质——光非互易与光隔离）

Wednesday 19 Jun 2019, 14:30 → 16:30 Asia/Shanghai

B326 (IHEP)

光隔离在激光防护、集成光学和量子信息处理中有重要应用。传统光隔离是通过块体磁光材料外加强磁场来实现，或者利用光学非线性材料或对材料施加时变调控。光——物质量子相互作用为调控光子传播提供了有力手段。我们基于手性腔和波导量子电动力学原理设计了光隔离器和环形器[1-4]。利用单个原子与手性回音壁模式光学微腔和手性光波导非对称耦合，构建了无磁场单光子隔离器和环形器[1, 2]。提出的方案被维也纳量子科技中心实验实现[1]，最近将报道的单光子隔离带宽提高了三个量级[2]。提出利用热原子系综与环形腔强耦合时微观热运动引起的多普勒频移诱导原子手性极化，并实验演示了常温非互易光传输和光隔离[3]。通过热原子系统构建手性交叉克尔光学非线性，突破了非线性光隔离中的动态互易限制，取得了常温光隔离和光环形器[4]。研究成果有望在量子信息处理得到广泛应用。 Abstract: Optical isolation promises very important applications in protecting lasers from damage by backscatter of light, integrated photonics, and quantum information processing. Conventional methods to achieve optical isolation typically requires the application of an external strong magnetic field to a bulky magneto-optical material, or optical nonlinear medium or tempo-spatial modulation of material. The light-matter quantum interaction provides a power tool to control the propagation of light. Here, we present four schemes for optical isolators and circulators, based on the chiral WGM cavity/waveguide QED [1-4]. By coupling a single quantum emitter asymmetrically to a chiral optical cavity or a chiral waveguide, we propose methods for the optical isolator and circulator at the single-photon level [1, 2]. The Vienna Center for Quantum Science and Technology experimentally demonstrated all our concepts in [1]. The second work [2] improves the nonreciprocal band for optical isolation by three orders in comparison with the world record so far. By inserting an ensemble of warm Rb atoms in a three-mirror ring resonator, we achieved a collectively strong coupling between atoms and the resonator mode. Making use of the microscopic Doppler shift of atomic resonance frequencies due to the thermal motion of atoms, we experimentally created a chiral susceptibility of atoms for the probe light. Furthermore, we achieved the optical nonreciprocal propagation and isolation at room temperature [3]. We also propose a method to create a chiral cross-Kerr optical nonlinearity in an ensemble of Rb atoms, implanted in a 1D waveguide. This chiral XKerr nonlinearity overcomes the dynamical reciprocity problem in nonlinear optics and allow one to realize optical isolators and circulators at room temperature. Our achievements may promise many applications of optical nonreciprocal devices in quantum information processing. 夏可宇介绍 夏可宇，南京大学现代工程与应用科学学院光学工程系教授。2007年中科院上海光机所获“光学”博士学位。先后在德国马克思—普朗克研究所、美国德克萨斯农工大学和澳大利亚麦考瑞大学工作。主要研究基于腔和波导量子力学的量子技术，包括超导量子电路、量子网络、量子测量及量子非线性光学等。在包括Science，Nature Photonics，PRL，PRX等国际著名学术期刊发表论文40篇。工作被《Science》、《Nature Photonics》和Phys.Org等媒体报道。提出的单光子量子隔离方案被著名的奥地利维也纳量子科技中心在Science和PRX上的文章实验验证。发表在Nature Photonics上的工作“Thermal-motion-induced non-reciprocal quantum optical system”被选为“2018中国光学十大进展——基础研究类”。 Profile of Professor Xia Dr. Keyu Xia is currently a full professor working at the College of Engineering and Applied Sciences in Nanjing University. He received his Doctoral degree of “Optics” in 2007 from Shanghai Institute of Optics and Fine Mechanics, CAS. He has been working in Max-Planck Institute for Nuclear Physics in Germany, Texas A&M University in USA, and Macquarie University in Australia. In 2017, he joined Nanjing University as a professor. Dr. Xia concentrates on the field of quantum optics and quantum information, in particular, superconducting quantum circuits, quantum network, quantum metrology and quantum nonlinear optics. He has 40 peer-reviewed publications in the top-level journals including Science, Nature Photonics, PRL, PRX and so on. His works have been reported by Science Magazine, Nature Photonics and media Phys.Org. The theoretical proposals for single-photon isolation have been realized by Prof. Arno Rauschenbeutel’s experimental group in Vienna Center of Quantum Science and Technology. His recent work of “Thermal-motion-induced quantum optical system”, published in Nature Photonics, is selected as “Top-10 progresses of Optics in China in 2018-Fundamental Research”. [1] Keyu Xia et al., “Reversible nonmagnetic single-photon isolation using unbalanced quantum coupling”, Phys. Rev. A 90, 043802 (2014). [2] Lei Tang et al., “On-chip chiral single-photon interface: isolation and unidirectional emission”, arXiv:1811.02957. [3] Shicheng Zhang et al., “Thermal-motion-induced non-reciprocal quantum optical system”, Nature Photon. 12, 744-748 (2018). [4] Keyu Xia, Franco Nori, and Min Xiao, “Cavity-free optical isolators and circulators using a chiral cross-Kerr nonlinearity”, Phys. Rev. Lett. 121, 203602 (2018).