Xia Keyu


Xia Keyu


OfficeC306 in New College Building

Email: keyu.xia@nju.edu.cn

Group web sitecwqed.nju.edu.cn

Research Field

Quantum optics, Quantum information, Quantum measurement and Micro/nanophotonics


Dr. Xia was awarded the “Optics” doctorate by Shanghai Institute of Optics and Fine Mechanics, CAS in 2017. He had been working in Max-Planck Institute for Nuclear Physics in Germany, Texas A&M University in USA, Macquarie University in Australia. His research interest includes the fields of quantum optics, quantum information and micro/nanophotonics. He has published more than 40 papers in the peer-reviewed journals, including Science, Nature Photonics, Physical Review Letters, Physical Review X etc., and 2 PCT patents. His research findings have been reported and viewed by magazines including Science, Nature, Nature Photonics and media Phys.Org. He and co-workers have published several high impact works, in particular, in chiral quantum optics and manipulation: (i) They theoretically proposed and demonstrated a proof-of-principle experiment to show the chiral susceptibility-momentum locking for constructing a chiral quantum optics and further demonstrated the non-magnetic optical isolation at room temperature. (ii) They proposed an optical medium with chiral Kerr nonlinearity to bypass the dynamic reciprocity in nonlinear optics for realizing optical isolators and circulators. (iii) They generated chiral vector vertex optical beams with orbital angular momentum on a photonic chip. They generalized the coupled-mode theory to be suitable for describing the generation and propagation of OAM optical beams. (iv) They proposed a practical protocol for single-photon isolation. Their protocol has been demonstrated by an experimental group in Vienna Center for quantum science and technology. (v) Based on the chiral optical four-wave-mixing process, they proposed a method for quantum non-demolition measurement of a traveling single photon. One of his achievements was awarded the honor of “Top 10 progresses of optics in China (basic research)” in 2018. Besides, Dr. Xia also has been serving as a reviewer for more than 10 internationally reputable journals including PRL, PRLPRA/BPRAppliedOptics ExpressJOSAB, and J. Phys. B.

Some representative achievements:

[1] Yuan Chen, Ke-Yu Xia*, Wei-Guan Shen, Jun Gao, Zeng-Quan Yan, Zhi-Qiang Jiao, Jian-Peng Dou, Hao Tang, Yan-Qing Lu*, and Xian-Min Jin*"Vector Vortex Beam Emitter Embedded in a Photonic Chip", Phys. Rev. Lett., 124, 153601 (2020). This work derived and proved the relation between the parameters of laser written optical waveguides and the laser energy, and provided the general coupled-mode theory formed in tensors suitable for describing the motion of the OAM optical beams.

[2] Shicheng Zhang, Yiqi Hu, Gongwei Lin, Yueping Niu, Keyu Xia*, Jiangbin Gong and Shangqing Gong, "Thermal-motion-induced non-reciprocal quantum optical system", Nat. Photonics, 12, 744-748 (2018). This work theoretically proposed and experimentally demonstrated the chiral susceptibility-momentum locking as a mechanism for building a chiral quantum optical system and further reported the magnetic-free optical isolation at room temperature. The work was selected as the “Top 10 progresses of optics in China (basic research) ”.

[3] 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). This work proposed an optical medium with chiral Kerr nonlinearity to bypass the dynamic reciprocity and to realize magnetic-free optical isolators and circulators at room temperature.

[4] Tao Li, Adam Miranowicz*, Xuedong Hu, Keyu Xia*, and Franco Nori*, "Quantum memory and gates using a \Lambda-type quantum emitter coupled to a chiral waveguide", Phys. Rev. A 97, 062318 (2018). Based on the chiral cavity quantum electrodynamics, this work proposed single-photon quantum memory and quantum gates.

[5] Keyu Xia*, Mattias Johnsson, Peter L. Knight and Jason Twamley,“Cavity-free scheme for nondestructive detection of a single optical photon”Phys. Rev. Lett., 116, 023601 (2016). This work proposed a protocol to conduct the quantum non-demolition measurement of a traveling single photon. It is reported by the magazine Science that “The proposed technique could offer a simpler route for implementing such quantum non-demolition detection strategies necessary for successful quantum information processing”.

[6] Keyu Xia, Yingbo He, Hongming Shen, Yuqing Cheng, Qihuang Gong and Guowei Lu, “Plasmonic nano-resonator enhanced one-photon luminescence from single gold nanorods”, Proc. of SPIE Micro+Nano Materials, Devices, and Systems, 9668, 96685B (2015). This conference presentation provided a plasmonic nanoresonator model for understanding the photoluminescence from a single gold nanoparticle. It also conceived the concept of “temperature nanometer” and “nanooven” and experimentally demonstrated the former part.

[7] Keyu Xia*, Guowei Lu, Gongwei Lin, Yuping Cheng, Yueping Niu, Shangqing Gong and Jason Twamley, “Reversible nonmagnetic single-photon isolation using unbalanced quantum coupling”, Phys. Rev. A 90(4), 043802(2014). This work presented a cavity/waveguide QED based proposal for single-photon isolation. The concept was experimentally demonstrated by the Vienna Center for Quantum Science and Technology, and was highly valued by a review in Nature.

[8] Keyu Xia and Jörg Evers, “Ground state cooling of a nanomechanical resonator in the nonresolved regime via quantum interference”, Phys. Rev. Lett., 103(22), 227203(2009). This work is the first proposal using the quantum interference to enhance the efficiency of laser cooling of a nanomechanical resonator.

Opening positions: Call for applicants for postdoctoral positions. The group can recruit 1-2 doctor students per year, and 1-3 master students per year.