The atom-photon quantum interface, interconnecting long-lived matter states and flying photon modes, plays an important role in many quantum systems involving atom-photon interactions. However strong nonlinear atom-photon interaction on atomic resonance in a single-photon level often is accompanied with loss. In this talk I will review the recent progress in lossless on-resonance nonlinear atom-photon interfaces based on electromagnetically induced transparency, and the applications in narrowband entangled photon pair generation, photonic quantum memory, mirrorless optical parametric oscillation, and nontraditional quantum heat engine.

Shengwang Du, Professor of Physics in The Hong Kong University of Science and Technology. Prof Du's experimental research mainly focuses on atomic, molecular, and optical (AMO) physics. On the fundamental side, his group is exploring the field of quantum optics and probing the quantum nature of light quanta with cold atoms. Prof. Du is also interested in developing applied optical microscopy tools for nano-micro material and cell bioimaging. Prof. Du is a Fellow of The Optical Society (OSA).

Quantum computers can in principle solve certain problems faster than classical computers. Despite substantial progress in the past decades, building quantum machines that can actually outperform classical computers for some specific tasks—a milestone termed as “quantum supremacy”—remained challenging. Boson sampling has been considered as a strong candidate to demonstrate the “quantum supremacy”. The challenge for realizing a large-scale boson sampling mainly lies in the lack of perfect quantum light sources. To this end, using single semiconductor quantum dot deterministically coupled to elliptical micropillars, we produced polarized single photons with near-unity purity, indistinguishability for >1000 photons, and high extraction efficiency—all combined in a single device compatibly and simultaneously [PRL 116, 020401 (2016)]. We built boson sampling machines with increasingly large number of photons to race against classical computers [Nature Photonics 11, 365 (2017)]. We also developed SPDC entangled two-photon source with simultaneously a collection efficiency of 97% and an indistinguishability of 96% between independent photons [PRL 121, 250505 (2018)]. The probabilistic nature of SPDC could be overcome using cascaded transition of a single quantum dot embedded in a broadband microcavity [PRL 122, 113602 (2019)].

Chao-Yang Lu obtained his Bachelor's degree from the University of Science and Technology of China in 2004, and obtained his PhD in Physics from the Cavendish Laboratory, University of Cambridge in 2011. Shortly after being a Fellow of Churchill College, he returned to China and is currently a Professor of Physics at the University of Science and Technology of China, where he focuses on research on scalable quantum photonics, quantum computation, and quantum foundations. He published more than 70 articles in Reviews of Modern Physics, Science, Nature, Nature research journals, PNAS and PRL, with 8000 citations. His work on quantum teleportation was selected as by IOP Physics World as “Breakthrough of the Year 2015”. His work on single-photon source and boson sampling was selected by Optical Society of American as one of "Optics in 2016" and one of "Optics in 2017". He has been awarded Young Qianren Talent, Hong Kong Qiushi Outstanding Young Scholars, National Natural Science Fund for Exceptional Young Scholars, First-Class National Natural Science Prize, Nature's "Science Star of China", OSA Fellow, China's Youth Wusi Medal, Fresnel Prize from the European Physical Society, TR35 China, AAAS Cleveland Prize, and Huangkun Prize on Semiconductor Physics from the Chinese Physical Society.

Solid state semiconductor quantum dots (QDs) embedded in microcavities emitting at optical fiber communication wavelengths, particularly in the telecom C-band, which offers the lowest attenuation losses in silica fibers have a lot of potential as a single photon source platform due to their various advantages of favorable manipulation and integration with various photonic elements. Cavity QED platform consisting of QDs in photonic crystals (PhCs) emitting at the telecom wavelengths are also considered as highly attractive for future applications in the solid-state quantum information processing.
Here, we report our recent progress in telecom wavelengths single-photon emitters from single InP-based QDs. Low QD density is obtained by careful control of the QD growth using a special growth technique and temperature processing. These QDs proved to have a nearly perfect single-photon emission and good coherence properties with clear signature of Rabi oscillations and large g-factors. Low-temperature single-dot spectroscopy exhibits sharp excitonic emission lines from single QDs and vanishing fine-structure splittings. The fabrication of InP-based PhC microcavities embedded with QDs is discussed. The influence of geometrical parameters on the quality factor enhancement, light out-coupling and the mode profiles of InP-PhC cavities are investigated. Suitable PhC are designed using finite difference time domain (FDTD) simulations. Sharp cavity modes with high quality factors are presented.

Mohamed Benyoucef has received his PhD from the University of Bristol, United Kingdom and Habilitation from the University of Kassel, Germany. He is the Head of Nano Optics and Photonics Group, at University of Kassel and a member of the Centre of Interdisciplinary Nanostructure Science and Technology (CINSaT). He is actively involved in research network related to quantum communication and quantum technology. His research focuses on the development of novel and advanced quantum nanoarchitectures fabricated on Si, GaAs, and InP substrates using molecular beam epitaxy system and study their specific aspects of quantum optics using various spectroscopic techniques. Integration of III-V semiconductor light sources in silicon and processing of nanostructured surfaces for optical devices, which open new perspectives in photonics and quantum information technology.

Absorption, emission from matter and scattering of light comprise the majority of optical phenomena in our world. Single quantum emitters are elementary sources of light and also most sensitive probes of optical fields and material boundaries. Among various kinds of nanoscopic emitters, colloidal quantum dots (QDs) have gained great attention due to intense broad-band absorption, tunable narrow-band emission, solution processibility, and compatibility with photonic structures. In this presentation, on nano-controlled coupling of one colloidal quantum dot to a dielectric nanotip for single-mode outcoupling of the single photons We show in-situ deciphering the charging status, and precisely assessing the absorption cross section for neutral, positively-charged, and negatively-charged single core/shell CdSe/CdS QD. We demonstrate three-dimensional manipulation of the QD towards precise integration of nanophotonic structures and near-field imaging

Prof. Xue-Wen Chen graduated with Bachelor (2003) in Chu Kochen Honors College and Ph.D. (2008) in Optics both from Zhejiang University, China. He was a Postdoctoral fellow at the Laboratory for Physical Chemistry, Swiss Federal Institute of Technology Zurich (ETH Zurich) and a research scientist at the Max-Planck Institute for the Science of Light (MPL, Germany). In June 2014, He accepted the national “Thousand Plan (Youth)” award from China and joined the School of Physics Huazhong University of Science and Technology (HUST) as professor. His research interests include experimental and theoretical studies of solid-state quantum optics and photonics at the nanometer scale.

Controlling electron motion by strong electromagnetic field, occurring on the attosecond (10^-18 seconds) timescale, is the heart of “lightwave electronics”. Until so far, various light-field driven effect has been explored, such as sub-optical-cycle photoemission from metal tips, interband tunneling in dielectrics and semiconductors, and high harmonic generation from bulky or two dimensional crystals. However, much less is known about light-field driven effect from one dimensional quantum confined electronic states. Among various one dimensional nanomaterials, Carbon nanotube is a promising platform to achieve light-field driven electron dynamics, because their wide bandwidth light field enhancement and high damage threshold. Here, we show that the photoemission yield induced from carbon nanotubes by intense laser pulses exhibited 20 power law of the laser intensity. The photoemission in such regime induced by few-cycle laser pulses can be sensitively modulated by the carrier-envelope phase, with a total current modulation contrast up to 100%, indicating an access into deep light-field driven regime. We expect these results to provide design philosophy for light-wave electronics.

Dr. Qing Dai is a professor in Nanophotonics at National Center for Nanoscience and Technology (NCNST), China. He is a cofounder and director of the Division of Nanophotonics at NCNST. His current research focuses on Nanophotonics, including high quality nanomaterials and nanostructures design and fabrication; plasmonic properties and surface enhanced spectroscopy; high spatial nearfield optical characterization and ultrafast electron emission. He has published over 60 peer-reviewed papers in reputed international journals, including Nature Communications and Advanced Materials. He is a regular reviewer of various high-impact journals such as Nature Materials, Advanced Materials, Nanoscale, ACS Nano and Nano Letters.

Linear operations on an N-dimensional vector are a powerful tool both for quantum optics and for classical optical information processing. Based on orbital angular momentum (OAM) states, the concepts of “quasi-angle” state and “quasi-OAM” state are introduced to form the high-dimensional optical Hilbert space and a linear states transformation method have been proposed.
Furthermore, we have proposed and demonstrated a non-cascaded approach to perform arbitrary unitary and non-unitary linear operations for N-dimensional phase-coherent spatial modes. Our approach is a simple, fixed, error-tolerant and scalable scheme based on meticulously designed phase gratings. According to experimental results, the unitary transformation matrix has been realized with dimensionalities ranging from 7 to 24 with corresponding fidelities from 95.1% to 82.1%. Besides the unitary operations, non-unitary operators can also be implemented. As a concrete example, a 4╳16 matrix is presented for the state tomography of a 4-level quantum system, with a fidelity of 94.9%.

Dr. Xue Feng received his BS, MS and PhD degrees from Tsinghua University in 1999, 2002 and 2005, respectively. Since 2005, he has been a faculty in Department of Electronic Engineering, Tsinghua University, Beijing, China.
Dr. Xue Feng has published more than 150 papers on academic journals and conferences with topics of optoelectronic devices. From 2009, he is dedicated to the integrated optoelectronic devices with nano/micro structures. The main research interests include integrated photonic orbital angular momentum emitter, new photonic functional devices and photonic integrated circuit.

Ultrahighly-sensitive photodetectors are desirable for optoelectronics. In this paper, three types of ultrahighly-sensitive photodetectors are developed. First is transfer-free graphene/Cu2O quantum dot photodetector. Graphene attracts great attention due to its outstanding electrical, optical and mechanical properties, which make it appealing in optoelectronics and photodetection applications. An internal current gain mechanism is proposed based on a 2D/0D photodetection system. Carrier density in the 2D material can be amplified by Fermi level modulation when a 0D quantum dot absorbs photons. An ultrahigh responsivity over 1010 A W-1 and fW light detectivity at room temperature are achieved by a transfer-free hybrid graphene/Cu2O quantum dot photodetector. In order to verify the internal current gain mechanism, ultrahigh sensitivity of ~109 A W-1 is also achieved in graphene/GaN quantum dot photodetector system. The third type of ultrahighly-sensitive photodetector is conventional avalanche photodiode operating in the Geiger mode, which is also called single-photon avalanche diode (SPAD), with the single photon sensitivity. We solved the confliction between photon detection efficiency and timing jitter, which is ~20% and ~22ps, respectively.

Professor Xia Guo is from Beijing University of Posts and Telecommunications. Her research interest is mainly the development of semiconductor optoelectronic devices, including single photon avalache photodiodes, vertical-cavity surface-emitting diodes, and light-emitting diodes. She has presided over more than 20 scientific research projects, such as the key projects of the National Natural Science Foundation and the national key R&D projects. She has published more than 100 SCI papers in academic journals.

Evidence for Bell’s nonlocality is so far mainly restricted to microscopic systems, where the elements of reality that are negated predetermine results of measurements to within one spin unit. Any observed nonlocal effect (or lack of classical predetermination) is then limited to no more than the difference of a single photon or electron being detected or not (at a given detector). In this paper, we analyze experiments that report Einstein-Podolsky-Rosen (EPR) steering form of nonlocality for mesoscopic photonic or Bose-Einstein condensate (BEC) systems. Using an EPR steering parameter, we show how the EPR nonlocalities involved can be quantified for four-mode states, to give evidence of nonlocal effects corresponding to a two-mode number difference of 105 photons, or of several tens of atoms (at a given site). We also show how the variance criterion of Duan-Giedke-Cirac and Zoller for EPR entanglement can be used to determine a lower bound on the number of particles in a pure two-mode EPR entangled or steerable state, and apply to experiments.

Dr. Qiongyi He is a “Talent-100” Professor at Peking University. She joined the faculty of Institute of Modern Optics at Peking University in January 2012, after carrying postdoctoral at University of Queensland and Swinburne University of Technology in Australia, undertaking Australian Postdoctoral Fellowship (APD) and Discovery Early Career Research Award (DECRA). She received the “Excellent Young Scholar Award” granted by National Natural Science Foundation of China (NSFC) and “The Changjiang (Yangtze River) Youth Scholar Award” selected by Ministry of Education of China in 2017. Her research interests lie in the fields of theory and applications of general quantum correlations for quantum information science.

Fabry-Perrot (FP) microcavities with metal or DBR (distributed Bragg reflector)-coated mirrors provide an excellent platform for investigating the collective behavior of confined 2-dimensional photons and polaritons. The TE-TM mode splitting in such cavities acts as an effective magnetic field, leading to photonic spin-orbit (SO) coupling effect that the pseudospin of cavity photons changes anisotropically with their momenta. Such mechanism has led to interesting observations including optical spin-Hall effect, magnetic-monopole-like half solitons, spinor condensate with half-quantum circulation, and polaritonic topological insulators.
In this paper, we report the SO coupling effect in an open-access microcavity consisting of planar and concave DBR-coated cavity mirrors separated by a micro-sized gap. A combination of the SO coupling and the lateral photonic potential gives rise to new eigenstates of spin vortices and optical Skyrmions. We show that those states provide vector vortex beam lasing with ultrasmall mode volume, whose pseudospin features can be tuned by varying the cavity length. Furthermore, by incorporating optically-active organic microcrystals inside the FP microcavity, we show the direct measurement of pseudospin-dependent Berry curvature and quantum metric in geometrically nontrivial bands preserving time reversal symmetry. These studies show promising applications in high-efficiency quantum light sources and pseudo-spin mediated topological photonic devices.

Feng Li got his bachelor's and master's degree at Tianjin University in China in 2006 and 2008. He got his PhD at CNRS and the University of Nice Sophia-Antipolis in France in 2013, supported by the European Marie-Curie ITN project CLERMONT4. Then he worked as a research associate at the University of Sheffield in UK from January 2014 to May 2017. Feng Li joined Xi'an Jiaotong University (China) as a professor in June 2017, with main research interest in light-matter interaction in microcavities and nanostructures.

In this talk, we will review our recent efforts on hybrid integration of quantum dot single photon sources on silicon photonics circuits, as a first step toward large scale photonic quantum information processors. We employed transfer printing for assembling the III-V semiconductor based emitters on the CMOS-processed photonic chips. The pick-and-place assembly process enables placing pre-selected quantum-dot single photon guns on desired positions in the circuits. This may allow for overcoming the difficulties in the heterogeneous integration process associated with the inherit randomness in emission wavelengths and positions of self-assembled quantum dots. We will also show that the integrated quantum dot emitter can couple to the underlying silicon waveguide with a theoretical efficiency close to unity. The use of a carefully-designed photonic crystal nanobeam cavity is the key to achieve this high efficiency. Experimentally, we observed a high coupling efficiency over 70%. Another interesting topic to be discussed is the realization of a quantum-dot-based cavity quantum electrodynamics system on a silicon chip, which was in strong coupling regime and exhibited an anti-crossing between the quantum dot and cavity mode.

Yasutomo Ota received a B.E. (2006) in Mechanical Engineering from Osaka Prefecture University and a M.E (2008) and a Ph.D. (2011) in Electrical Engineering from The University of Tokyo. He joined Institute for Nano Quantum Information Electronics, The University of Tokyo as a project assistant professor in 2011 and has been a project associate professor since 2016. His research interest lies in, but not limited to light-matter interactions in photonic nanostructures.

Heisenberg's uncertainty relation is one of basic principle in quantum mechanics, which gives a fundamental limitation for joint measurements of two incompatible quantum observables. We experimentally test the error-tradeoff uncertainty relation by using a continuous-variable Einstein-Podolsky-Rosen (EPR) entangled state. We also experimentally test the error-disturbance uncertainty relation for different Gaussian states by using a heterodyne measurement system. Our experimental results demonstrate that Heisenberg's error-tradeoff uncertainty relation is violated in some cases, while the Ozawa's and Brainciard's error-tradeoff uncertainty relation for continuous variables are valid. Our work is helpful not only in understanding fundamentals of physical measurement but also in developing continuous variable quantum information technology.

Xiaolong Su is currently a professor at State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-electronics, Shanxi University. His research interest is focused on quantum information with continuous variables and hybrid quantum information processing. He has published over 50 papers on scientific journals, including Nature Communications, Phys. Rev. Lett., et. al. He is the winner of National Science Fund for Excellent Young Scholars in 2015 and Youth Sanjin Scholar in Shanxi Provience.

Semiconductor perovskite nanocrystals (NCs) have just emerged as a novel type of semiconductor nanostructure capable of emitting single photons without the influence of dark-exciton emission. Moreover, the suppressions of both the photoluminescence (PL) blinking and spectral diffusion effects were successfully demonstrated in single perovskite NCs. In this talk, we will show our recent progress made on the optical studies of single perovskite CsPbI3 NCs at the cryogenic temperature, focusing mainly on the bright-exciton fine-structure splitting (FSS), coherent optical property and the electrical manipulation. First, the bright-exciton FSS is manifested as either a doublet or a triplet PL peak, which should correspond to the weak and strong quantum confinement in a single CsPbI3 NC according to our experimental and theoretical investigations. Second, the first-order photon correlation and PL excitation measurements are performed on single CsPbI3 NCs, which allow us to further realize the quantum interference measurement to yield an exciton dephasing time of about 10 ps. Third, strong quantum-confined Stark effect is observed in single CsPbI3 NCs upon being biased by an external electrical field, with the FSS value being greatly reduced to signify potential emission of polarization-entangled photon pairs. The above achievements will surely advance single perovskite NCs into the quantum information regime, opening up an alternative yet prospective research direction beyond their traditional applications such as in optoelectronic devices and bioimaging.

Dr. Xiaoyong Wang obtained his bachelor's and master's degrees of optical engineering from Tianjing University, China, and his doctoral degree in physics from University of Arkansas at Fayetteville, US. After doing his postdoctoral researches from University of Texas at Austin and University of Rochester in the US, Dr. Xiaoyong Wang took a full professor position in the School of Physics at Nanjing University, China, and is now the chair for the department of optical science.

Orbital angular momentum (OAM) arising from the helical phase structure of a photon could be used to encode a qubit or a qudit. It plays an important role for the photonic quantum information processing since it could result in some unique functions such as entanglement with high momentum and in high dimension. In this talk, I will start with a brief introduction to OAM and a short review of the recent advances in OAM application in quantum information processing. Then, I will in particular talk about our work of applications of quantum entanglement with OAM. By simultaneously manipulating OAM and Spin angular momentum (SAM), we implemented the first quantum teleportation of multiple DoFs of a single photon [Nature 518, 516-519 (2015)]. Then, together with the high-brightness photon entanglement source for ten-photon entanglement [Phys. Rev. Lett. 117, 210502 (2016)], we successfully demonstrated the 18-qubit entanglement with six photons' three degrees of freedom including SAM, OAM and path [Phys. Rev. Lett. 120, 260502 (2018)].

Xi-Lin Wang now is a professor at Nanjing University. His research interest focus on quantum optics and quantum information with orbital angular momentum. His contribution as the main author include: the first quantum teleportation with multiple degrees of freedom, which was elected as “Breakthrough of the Year 2015” by IOP Physics World; the first ten-photon entanglement, refreshing the world record; and the first 18-qubit entanglement with six photons' three degrees of freedom, which was reported by Phys. Org. with a title of “18-qubit entanglement sets new record”. He has so far published 30 articles in peer-reviewed journals, including 1 in Nature, 10 in Physical Review Letters, and his publications have attracted more than 1200 SCI citations.

Entanglement is explored within the framework of quantum resource theories, which can also be used to investigate other non-classical features of quantum mechanics in a systematic way. A concept underlying many facets of non-classicality, including entanglement, is the superposition principle. Since a quantum system naturally decoheres in the presence of unavoidable interactions between the system and its environment, superposition is itself a resource, which is studied in the recently developed resource theory of quantum coherence. In this talk, I will review the experimental progress in measurement of quantum coherence, interconversion between quantum coherence and quantum correlation, and the applications of quantum coherence resource theory.

Dr. Guoyong xiang, professor of physics, have received his Ph.D. degree from University of Science and Technology of China (USTC) in 2005. Dr. Xiang is an experimental physicist and his research interest is focused on quantum information, quantum precision measurement and fundamental problems of quantum mechanics. Dr. Xiang was supported by National Natural Science Foundation--Outstanding Youth Foundation.

Einstein-Podolsky-Rosen (EPR) steering describes the ability of one observer to nonlocally steer the other observer's state through local measurement. EPR steering stands between entanglement and Bell nonlocality in the hierarchy, which provides a novel insight into quantum nonlocality. In this report, I will introduce our recent works on the experimental investigation of EPR steering. Based on the All-Versus-Nothing proof, we demonstrate an EPR steering game. We then provide a necessary and sufficient condition for EPR steering and clearly demonstrate the distinguished one-way EPR steering. We further implement the task of subchannel discrimination where the probabilities of correct discrimination are clearly enhanced by exploiting steerable states. Our woks provide a particularly strong perspective for understanding EPR steering and have potential applications in asymmetric quantum information processing.

Jin-Shi Xu received his Ph.D. degree in optics from University of Science and Technology of China (USTC) in 2009. He became a professor in USTC since 2016. He was awarded the national best PhD thesis prize in 2011 and Wang Daheng optics prize in 2015. He was supported by the National Science Fund for Distinguished Young Scholars. His current research interests include linear optical quantum simulation, spin-photon interface and fundamental quantum physics.

Distributing quantum information using photons through quantum channels is essential for building future quantum networks. The scalability needed for such quantum networks can be realized by employing photonic quantum bits (qubits) that are multiplexed into time and/or frequency, and light-matter interfaces that are able to store and process such qubits with large time-bandwidth product and multimode capacities. Despite important progress in developing such devices, the demonstration of these capabilities using nonclassical light remains challenging. Here, employing the atomic frequency comb quantum memory protocol in a cryogenically cooled (800 mK) erbium-doped optical fibre, we report the quantum storage of heralded single photons at a telecom-wavelength (1.53 m) with a time-bandwidth product approaching 800. Furthermore, we demonstrate frequency-multimode storage and memory-based spectral-temporal photon manipulation. Notably, our demonstrations rely on fully integrated quantum technologies operating at telecommunication wavelengths. With improved storage efficiency (by cooling the erbium-doped optical fibre to 10 mK), our light-matter interface would become a useful quantum device in future quantum networks.

Dr. Qiang Zhou is a professor at the University of Electronic Science and Technology, with research interests in quantum information technologies, quantum internet, light-matter interface, quantum devices, nonlinear optics, nano-photonics and quantum photonics. He received the B.S. degree from University of Electronic Science and Technology in Optoelectronic Information and the Ph.D. degree from Tsinghua University in Electronic Science and Technology. He was awarded the 2011-Tsinghua outstanding doctoral thesis prize for his work in fibre based quantum light source. He has authored more than 50 papers in referred journals and conferences. He presented more than 10 talks (including 5 invited talks) in international conferences. He is a principal investigator for National Key R&D Program of China.