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Comparative study of discrete Boltzmann model and Navier-Stokes

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Journal of physics: Conference Series 2018年第1期1113卷

作者： Yudong Zhang Aiguo Xu Guangcai Zhang Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing 100088 China Key Laboratory of Transient Physics Nanjing University of Science and Technology Nanjing 210094 China Center for Applied Physics and Technology MOE Key Center for High Energy Density Physics Simulations College of Engineering Peking University Beijing 100871 China

Discrete Boltzmann model (DBM) is a type of coarse-grained mesoscale kinetic model derived from the Boltzmann equation. Physically, it is roughly equivalent to a hydrodynamic model supplemented by a coarse-grained model for the relevant thermodynamic non-equilibrium (TNE) behaviours. The Navier-Stokes (NS) model is a traditional macroscopic hydrodynamic model based on continuity hypothesis and conservation laws. In this study, the two models are compared from two aspects, physical capability and computational cost, by simulating two kinds of flow problems including the thermal Couette flow and a Mach 3 step problem. In the cases where the TNE effects are weak, both the two models give accurate results for the hydrodynamic behaviour. Besides, DBM can provide more detailed non-equilibrium information, while the NS is more efficient if concern only the density, momentum, energy and their derived quantities. It is concluded that, if the TNE effects are strong or are to be investigated, the NS is insufficient while DBM is a good choice. While in the cases where the TNE effects are weak and only the macro flow fields are to be studied, the NS is more preferable.

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Framework for complex quantum state generation and coherent control based on on-chip frequency combs

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Framework for complex quantum state generation and coherent ...

Frontiers in Optics, FIO 2018

作者： Roztocki, Piotr Reimer, Christian Sciara, Stefania Cortés, Luis Romero Zhang, Yanbing Wetzel, Benjamin Islam, Mehedi Cino, Alfonso Chu, Sai T. Little, Brent E. Moss, David J. Caspani, Lucia Azaña, José Kues, Michael Morandotti, Roberto INRS-EMT 1650 Boulevard Lionel-Boulet VarennesQCJ3X 1S2 Canada John A. Paulson School of Engineering and Applied Sciences Harvard University Cambridge02138 United States Department of Energy Information Engineering and Mathematical Models University of Palermo Palermo Italy School of Mathematical and Physical Sciences University of Sussex Falmer BrightonBN 1 9RH United Kingdom Department of Physics and Material Science City University of Hong Kong Tat Chee Avenue Hong Kong Hong Kong State Key Laboratory of Transient Optics and Photonics Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Science Xi'an China Centre for Micro Photonics Swinburne University of Technology HawthornVIC3122 Australia Institute of Photonics Department of Physics University of Strathclyde GlasgowG1 1RD United Kingdom School of Engineering University of Glasgow Rankine Building Oakfield Avenue GlasgowG12 8LT United Kingdom Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Chengdu610054 China National Research University of Information Technologies Mechanics and Optics St. Petersburg Russia

Integrated frequency combs introduce a scalable framework for the generation and manipulation of complex quantum states (including multi-photon and high-dimensional states), using only standard silicon chip and fiber ... 详细信息

ISBN: (纸本)9781943580460

关键词： Coherent states Fiber to chip coupling Frequency combs Light sources Quantum information processing Quantum optics

Beam dynamics in disordered PT-symmetric optical lattices based on eigenstate analyses

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Physical Review A 2017年第3期95卷 033804-033804页

作者： Xiankun Yao Xueming Liu State Key Laboratory of Transient Optics and Photonics Xi’an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi’an 710119 China State Key Laboratory of Modern Optical Instrumentation Department of Optical Engineering Zhejiang University Hangzhou 310027 China School of Physics and Electronic Science Hunan University of Science and Technology Xiangtan 411201 People's Republic of China

Wave functions will experience a localization process when evolving in disordered lattices. Here, we have demonstrated the effects of disordered PT-symmetric potentials on wave-function characteristics in optics based on eigenstate analyses. In weak-disorder cases, by using the tight-binding approximation method, a conclusion is obtained that the increasing of the imaginary part of potential can enhance the diffraction, while the increasing disorder will block the diffraction and lead to localization. In the general case, band theory is used for band-structure analysis of three bands. We find that the disorder has a smaller effect on the higher-order band, which is proved by the beam evolutions. Our work may be instructive for realizing beam path control by manipulating the strengths of disorder and gain and/or loss of lattice.

关键词： Light propagation, transmission & absorption Optical coherence Photonic crystals

On-chip frequency combs and telecommunications signal processing meet quantum optics

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Frontiers of Optoelectronics 2018年第2期11卷 134-147页

作者： Christian REIMER Yanbing ZHANG Piotr ROZTOCKI Stefania SCIARA Luis Romero CORTES Mehedi ISLAM Bennet FISCHER Benjamin WETZEL Alfonso Carmelo CINO Sai Tak CHU Brent LITTLE David MOSS Lucia CASPANI Jose AZANA Michael KUES Roberto MORANDOTTI Institut National de la Recherche Scientifique - Centre Energie Matrriaux et Telecommunications (INRS-EMT) 1650 Boulevard Lionel-Boulet Varennes Qurbec J3X 1S2 Canada Department of Energy Information Engineering and Mathematical Models University of Palermo Palermo Italy Department of Physics & Astronomy University of Sussex Falmer Brighton BN1 9QH UK Department of Physics and Material Science City University of Hong Kong Tat Chee Avenue Hong Kong China State Key Laboratory of Transient Optics and Photonics Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi'an 710119 China Centre for Micro Photonics Swinburne University of Technology Hawthorn Victoria 3122 Australia Institute of Photonics Department of Physics University of Strathclyde Glasgow G1 1RD UK School of Engineering University of Glasgow Rankine Building Oakfield Avenue Glasgow G 12 8LT UK Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Chengdu 610054 China National Research University of Information Technologies Mechanics and Optics St Petersburg 197101 Russia

Entangled optical quantum states are essential towards solving questions in fundamental physics and are at the heart of applications in quantum information science. For advancing the research and development of quantum technologies, practical access to the generation and manipulation of photon states carrying significant quantum resources is required. Recently, integrated photonics has become a leading platform for the compact and cost- efficient generation and processing of optical quantum states. Despite significant advances, most on-chip non- classical light sources are still limited to basic bi-photon systems formed by two-dimensional states （i.e., qubits）. An interesting approach beating large potential is the use of the time or frequency domain to enabled the scalable on- chip generation of complex states. In this manuscript, we review recent efforts in using on-chip optical frequency combs for quantum state generation and telecommunica- tions components for their coherent control. In particular, the generation of bi- and multi-photon entangled qubit states has been demonstrated, based on a discrete time domain approach. Moreover, the on-chip generation of high-dimensional entangled states （quDits） has recentlybeen realized, wherein the photons are created in a coherent superposition of multiple pure frequency modes. The time- and frequency-domain states formed with on-chip frequency comb sources were coherently manipulated via off-the-shelf telecommunications compo- nents. Our results suggest that microcavity-based entangled photon states and their coherent control using accessible telecommunication infrastructures can open up new venues for scalable quantum information science.

关键词： nonlinear optics quantum optics entangledphotons

Photonic single sideband RF generator based on an integrated optical micro-ring resonator

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arXiv 2018年

作者： Xu, Xingyuan Wu, Jiayang Tan, Mengxi Nguyen, Thach G. Chu, Sai T. Little, Brent E. Morandotti, Roberto Mitchell, Arnan Moss, David J. Centre for Micro-Photonics Swinburne University of Technology HawthornVIC3122 Australia School of Engineering RMIT University MelbourneVIC3001 Australia Department of Physics and Material Science City University of Hong Kong Tat Chee Avenue Hong Kong State Key Laboratory of Transient Optics and Photonics Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Science Xi'an China INSR-Énergie Matériaux et Télécommunications 1650 Boulevard Lionel-Boulet VarennesQCJ3X 1S2 Canada Research University of Information Technologies Mechanics and Optics St. Petersburg Russia Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Chengdu610054 China

We demonstrate narrowband orthogonally polarized optical RF single sideband generation as well as dual-channel equalization based on an integrated dual-polarization-mode high-Q microring resonator. The device operates in the optical communications band and enables narrowband RF operation at either 16.6 GHz or 32.2 GHz, determined by the free spectral range and TE/TM mode interval in the resonator. We achieve a very large dynamic tuning range of over 55 dB for both the optical carrier-to-sideband ratio and the dual-channel RF equalization. Copyright © 2018, The Authors. All rights reserved.

关键词： Optical resonators

Tunable RF and microwave photonic sideband generator based on cascaded 49GHz and 200GHz integrated ring resonators

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arXiv 2018年

作者： Xu, Xingyuan Wu, Jiayang Jia, Linnan Tan, Mengxi Nguyen, Thach G. Chu, Sai T. Little, Brent E. Morandotti, Roberto Mitchell, Arnan Moss, David J. Centre for Micro-Photonics Swinburne University of Technology HawthornVIC3122 Australia RMIT University MelbourneVIC3001 Australia Department of Physics and Material Science City University of Hong Kong Hong Kong State Key Laboratory of Transient Optics and Photonics Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Science Xi'an China INRS-Énergie Matériaux et Télécommunications 1650 Boulevard Lionel-Boulet VarennesQCJ3X 1S2 Canada National Research Uni of Information Technologies Mechanics and Optics St. Petersburg Russia Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Chengdu610054 China

We demonstrate a continuously RF tunable orthogonally polarized optical single sideband (OP-OSSB) generator based on dual cascaded micro-ring resonators. By splitting the input double sideband signal into an orthogonally polarized carrier and lower sideband via TE- and TM-polarized MRRs, an OP-OSSB signal is generated. A large tuning range of the optical carrier to sideband ratio of up to 57.3 dB is achieved by adjusting the polarization angle of the input light. The operation RF frequency of the OP-OSSB generator can be continuously tuned with a 21.4 GHz range via independent thermal control of the two MRRs. Our device represents a competitive approach towards OP-OSSB generation with wideband tunable RF operation, and is promising for photonic RF signal transmission and processing in radar and communication systems. Copyright © 2018, The Authors. All rights reserved.

关键词： Optical resonators

Discrete Boltzmann Modeling of Compressible Flows

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arXiv 2017年

作者： Xu, Aiguo Zhang, Guangcai Zhang, Yudong Institute of Applied Physics and Computational Mathematics Beijing100088 China Center for Applied Physics and Technology MOE Key Center for High Energy Density Physics Simulations College of Engineering Peking University Beijing100871 China Key Laboratory of Transient Physics Nanjing University of Science and Technology Nanjing210094 China Graduate School China Academy of Engineering Physics Beijing100088 China

Mathematically, the typical difference of Discrete Boltzmann Model (DBM) from the traditional hydrodynamic one is that the Navier-Stokes (NS) equations are replaced by a discrete Boltzmann equation. But physically, this replacement has a significant gain: a DBM is roughly equivalent to a hydrodynamic model supplemented by a coarse-grained model of the Thermodynamic Non-Equilibrium (TNE) effects, where the hydrodynamic model can be and can also beyond the NS. Via the DBM, it is convenient to perform simulations on systems with flexible Knudsen number. The observations on TNE are being obtaining more applications with time. Copyright © 2017, The Authors. All rights reserved.

关键词： Navier Stokes equations

A Radio Frequency Channelizer based on Cascaded Integrated Micro-ring Resonator Optical Comb Sources and Filters

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arXiv 2018年

作者： Xu, Xingyuan Wu, Jiayang Nguyen, Thach G. Chu, Sai T. Little, Brent E. Morandotti, Roberto Mitchell, Arnan Moss, David J. Centre for Micro-Photonics Swinburne University of Technology HawthornVIC3122 Australia School of Engineering RMIT University MelbourneVIC3001 Australia Department of Physics and Material Science City University of Hong Kong Tat Chee Avenue Hong Kong Hong Kong State Key Laboratory of Transient Optics and Photonics Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Science Xi'an China INSR-Énergie Matériaux et Télécommunications 1650 Boulevard Lionel-Boulet VarennesQCJ3X 1S2 Canada National Research University of Information Technologies Mechanics and Optics St. Petersburg Russia Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Chengdu610054 China

We report a broadband RF channelizer based on an integrated optical frequency Kerr micro-comb source, with an RF channelizing bandwidth of 90 GHz, a high RF spectral slice resolution of 1.04 GHz, and experimentally verify the RF performance up to 19 GHz. This approach to realizing RF channelizers offers reduced complexity, size, and potential cost for a wide range of applications to microwave signal detection. Copyright © 2018, The Authors. All rights reserved.

关键词： Optical resonators

Photonic RF and microwave reconfigurable filters and true time delays based on an integrated optical Kerr frequency comb source

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arXiv 2018年

作者： XU, XINGYUAN WU, JIAYANG NGUYEN, THACH G. SHOEIBY, MEHRDAD CHU, SAI T. LITTLE, BRENT E. MORANDOTTI, ROBERTO MITCHELL, ARNAN MOSS, DAVID J. Centre for Micro-Photonics Swinburne University of Technology HawthornVIC3122 Australia RMIT University MelbourneVIC3001 Australia Department of Physics and Material Science City University of Hong Kong Tat Chee Avenue Hong Kong China State Key Laboratory of Transient Optics and Photonics Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Science Xi'an China INRS-Énergie Matériaux et Télécommunications 1650 Boulevard Lionel-Boulet VarennesQCJ3X 1S2 Canada National Research University of Information Technologies Mechanics and Optics St. Petersburg Russia Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Chengdu610054 China

We demonstrate advanced transversal radio frequency (RF) and microwave functions based on a Kerr optical comb source generated by an integrated micro-ring resonator. We achieve extremely high performance for an optical true time delay aimed at tunable phased array antenna applications, as well as reconfigurable microwave photonic filters. Our results agree well with theory. We show that our true time delay would yield a phased array antenna with features that include high angular resolution and a wide range of beam steering angles, while the microwave photonic filters feature high Q factors, wideband tunability, and highly reconfigurable filtering shapes. These results show that our approach is a competitive solution to implementing reconfigurable, high performance and potentially low cost RF and microwave signal processing functions for applications including radar and communication systems. Copyright © 2018, The Authors. All rights reserved.

关键词： Optical resonators