The rapid development in the digital circuit design enhances the applications on very large scale integration era. Encoders are one among the digital circuits found in all communication systems. The polar encoding is ...The rapid development in the digital circuit design enhances the applications on very large scale integration era. Encoders are one among the digital circuits found in all communication systems. The polar encoding is mainly meant for its channel achieving property. It finds its application in communications, sensing and information theory. This coding proposed by Erdal Arikan is significant because of its zero error floors and simple architecture for hardware implementation. In this paper, a folded polar encoder is designed to start from the fully parallel architecture and proceeds with its data flow graph, delay requirement calculation, lifetime analysis and register allocation, which results in a very large scale integration architecture with minimum hardware utilization. The results are simulated for 4 and 8 parallel folded 32-bit polar encoder using Xilinx 14.6 ISIM and implemented in Virtex 5 field programmable gate array. A comparison is made on fully parallel and various folding techniques based on their resource utilization.展开更多
Polarization coding is a specific encoding method by using the polarization state of optical signal carrying coded in- formation. It focuses on nonlinear effects, polarization mode dispersion and other issues in high-...Polarization coding is a specific encoding method by using the polarization state of optical signal carrying coded in- formation. It focuses on nonlinear effects, polarization mode dispersion and other issues in high-speed fiber-optic communi- cations. This paper presents a measurement method for polarization state based on elastic-optic modulator. This method not only retains the original advantages of elastic-optic modulator for polarization measurement, but also overcomes the defects of existing methods including high modulation frequency and invalid collection by using array detector. Matlab simulation and experimental verification scheme are given. The feasibility of this method is verified through theoretical analysis, and simulation and experimental results are carried out. The error analysis of the measurement results shows that the method can meet the measurement requirements and provide conditions for using the polarization encoding in high-speed communication.展开更多
Quantum communication networks,such as quantum key distribution(QKD)networks,typically employ the measurement-resend mechanism between two users using quantum communication devices based on different quantum encoding ...Quantum communication networks,such as quantum key distribution(QKD)networks,typically employ the measurement-resend mechanism between two users using quantum communication devices based on different quantum encoding types.To achieve direct communication between the devices with different quantum encoding types,in this paper,we propose encoding conversion schemes between the polarization bases(rectilinear,diagonal and circular bases)and the time-bin phase bases(two phase bases and time-bin basis)and design the quantum encoding converters.The theoretical analysis of the encoding conversion schemes is given in detail,and the basis correspondence of encoding conversion and the property of bit flip are revealed.The conversion relationship between polarization bases and time-bin phase bases can be easily selected by controlling a phase shifter.Since no optical switches are used in our scheme,the converter can be operated with high speed.The converters can also be modularized,which may be utilized to realize miniaturization in the future.展开更多
Integration of phase-change materials(PCMs)created a unique opportunity to implement reconfigurable photonics devices that their performance can be tuned depending on the target application.Conventional PCMs such as G...Integration of phase-change materials(PCMs)created a unique opportunity to implement reconfigurable photonics devices that their performance can be tuned depending on the target application.Conventional PCMs such as Ge-Sb-Te(GST)and Ge-Sb-Se-Te(GSST)rely on melt-quench and high temperature annealing processes to change the organization of the molecules in the materials’crystal.Such a reorganization leads to different optical,electrical,and thermal properties which can be exploited to implement photonic memory cells that are able to store the data at different resistance or optical transmission levels.Despite the great promise of conventional PCMs for realizing reconfigurable photonic memories,their slow and extremely power-hungry thermal mechanisms make scaling the systems based on such devices challenging.In addition,such materials do not offer a stable multi-level response over a long period of time.To address these shortcomings,the research carried out in this study shows the proof of concept to implement next-generation photonic memory cells based on two-dimensional(2D)birefringence PCMs such as SnSe,which offer anisotropic optical properties that can be switched ferroelectrically.We demonstrate that by leveraging the ultrafast and low-power crystallographic direction change of the material,the optical polarization state of the input optical signal can be changed.This enables the implementation of next-generation high-speed polarization-encodable photonic memory cells for future photonic computing systems.Compared to the conventional PCMs,the proposed SnSe-based photonic memory cells offer an ultrafast switching and low-loss optical response relying on ferroelectric property of SnSe to encode the data on the polarization state of the input optical signal.Such a polarization encoding scheme also reduces memory read-out errors and alleviates the scalability limitations due to the optical insertion loss often seen in optical transmission encoding.展开更多
Full waveform inversion(FWI)is an extremely important velocity-model-building method.However,it involves a large amount of calculation,which hindsers its practical application.The multi-source technology can reduce th...Full waveform inversion(FWI)is an extremely important velocity-model-building method.However,it involves a large amount of calculation,which hindsers its practical application.The multi-source technology can reduce the number of forward modeling shots during the inversion process,thereby improving the efficiency.However,it introduces crossnoise problems.In this paper,we propose a sparse constrained encoding multi-source FWI method based on K-SVD dictionary learning.The phase encoding technology is introduced to reduce crosstalk noise,whereas the K-SVD dictionary learning method is used to obtain the basis of the transformation according to the characteristics of the inversion results.The multiscale inversion method is adopted to further enhance the stability of FWI.Finally,the synthetic subsag model and the Marmousi model are set to test the effectiveness of the newly proposed method.Analysis of the results suggest the following:(1)The new method can effectively reduce the computational complexity of FWI while ensuring inversion accuracy and stability;(2)The proposed method can be combined with the time-domain multi-scale FWI strategy flexibly to further avoid the local minimum and to improve the stability of inversion,which is of significant importance for the inversion of the complex model.展开更多
For the requirement of quantum photonic integration in on-chip quantum information,we propose a scheme to realize quantum controlled-Z(CZ)gates through single gradient metasurface.Using its parallel beam-splitting fea...For the requirement of quantum photonic integration in on-chip quantum information,we propose a scheme to realize quantum controlled-Z(CZ)gates through single gradient metasurface.Using its parallel beam-splitting feature,i.e.,a series of connected beamsplitters with the same splitting ratio,one metasurface can support a polarization encoding CZ gate or path encoding CZ gate,several independent CZ gates,and cascade CZ gates.Taking advantage that the path of output state is locked by the polarization of input state,path encoding CZ gates can efficiently filter out bit-flip errors coming from beam-splitting processes.These CZ gates also have the potential to detect quantum errors and generate high-dimensional entanglement through multi-degree-of-freedom correlation on metasurfaces.By integrating quantum CZ gates into a single metasurface,our results open an avenue for high-density and multifunctional integration of quantum devices.展开更多
The quantum key distribution(QKD)network is a promising solution for secure communications.In this paper,we proposed a polarization-independent phase-modulated polarization encoding module,and it can be combined with ...The quantum key distribution(QKD)network is a promising solution for secure communications.In this paper,we proposed a polarization-independent phase-modulated polarization encoding module,and it can be combined with a dense wavelength division multiplexer(DWDM)to achieve multi-user QKD.We experimentally test the encoding module with a repetition rate of 62.5 MHz,and its average quantum bit error rate(QBER)is as low as 0.4%.Finally,we implement a principle verification test for simultaneous QKD for 1 to 2 users in 100 min,and the average QBER of two users under the transmission distance of 1 km and 5 km is kept below 0.8%.Due to the use of polarization encoding,the module can also realize scalable network architecture in free-space QKD systems in the future.展开更多
文摘The rapid development in the digital circuit design enhances the applications on very large scale integration era. Encoders are one among the digital circuits found in all communication systems. The polar encoding is mainly meant for its channel achieving property. It finds its application in communications, sensing and information theory. This coding proposed by Erdal Arikan is significant because of its zero error floors and simple architecture for hardware implementation. In this paper, a folded polar encoder is designed to start from the fully parallel architecture and proceeds with its data flow graph, delay requirement calculation, lifetime analysis and register allocation, which results in a very large scale integration architecture with minimum hardware utilization. The results are simulated for 4 and 8 parallel folded 32-bit polar encoder using Xilinx 14.6 ISIM and implemented in Virtex 5 field programmable gate array. A comparison is made on fully parallel and various folding techniques based on their resource utilization.
文摘Polarization coding is a specific encoding method by using the polarization state of optical signal carrying coded in- formation. It focuses on nonlinear effects, polarization mode dispersion and other issues in high-speed fiber-optic communi- cations. This paper presents a measurement method for polarization state based on elastic-optic modulator. This method not only retains the original advantages of elastic-optic modulator for polarization measurement, but also overcomes the defects of existing methods including high modulation frequency and invalid collection by using array detector. Matlab simulation and experimental verification scheme are given. The feasibility of this method is verified through theoretical analysis, and simulation and experimental results are carried out. The error analysis of the measurement results shows that the method can meet the measurement requirements and provide conditions for using the polarization encoding in high-speed communication.
基金supported by the National Natural Science Foundation of China(Grant No.62001440).
文摘Quantum communication networks,such as quantum key distribution(QKD)networks,typically employ the measurement-resend mechanism between two users using quantum communication devices based on different quantum encoding types.To achieve direct communication between the devices with different quantum encoding types,in this paper,we propose encoding conversion schemes between the polarization bases(rectilinear,diagonal and circular bases)and the time-bin phase bases(two phase bases and time-bin basis)and design the quantum encoding converters.The theoretical analysis of the encoding conversion schemes is given in detail,and the basis correspondence of encoding conversion and the property of bit flip are revealed.The conversion relationship between polarization bases and time-bin phase bases can be easily selected by controlling a phase shifter.Since no optical switches are used in our scheme,the converter can be operated with high speed.The converters can also be modularized,which may be utilized to realize miniaturization in the future.
基金supported by the National Science Foundation(NSF)(Nos.CCF-2006788 and CNS-2046226)L.H.C.and J.Y.thank the support of Heising-Simons Faculty Fellowship.
文摘Integration of phase-change materials(PCMs)created a unique opportunity to implement reconfigurable photonics devices that their performance can be tuned depending on the target application.Conventional PCMs such as Ge-Sb-Te(GST)and Ge-Sb-Se-Te(GSST)rely on melt-quench and high temperature annealing processes to change the organization of the molecules in the materials’crystal.Such a reorganization leads to different optical,electrical,and thermal properties which can be exploited to implement photonic memory cells that are able to store the data at different resistance or optical transmission levels.Despite the great promise of conventional PCMs for realizing reconfigurable photonic memories,their slow and extremely power-hungry thermal mechanisms make scaling the systems based on such devices challenging.In addition,such materials do not offer a stable multi-level response over a long period of time.To address these shortcomings,the research carried out in this study shows the proof of concept to implement next-generation photonic memory cells based on two-dimensional(2D)birefringence PCMs such as SnSe,which offer anisotropic optical properties that can be switched ferroelectrically.We demonstrate that by leveraging the ultrafast and low-power crystallographic direction change of the material,the optical polarization state of the input optical signal can be changed.This enables the implementation of next-generation high-speed polarization-encodable photonic memory cells for future photonic computing systems.Compared to the conventional PCMs,the proposed SnSe-based photonic memory cells offer an ultrafast switching and low-loss optical response relying on ferroelectric property of SnSe to encode the data on the polarization state of the input optical signal.Such a polarization encoding scheme also reduces memory read-out errors and alleviates the scalability limitations due to the optical insertion loss often seen in optical transmission encoding.
基金jointly supported by the National Science and Technology Major Project(Nos.2016ZX05002-005-07HZ,2016ZX05014-001-008HZ,and 2016ZX05026-002-002HZ)National Natural Science Foundation of China(Nos.41720104006 and 41274124)+2 种基金Chinese Academy of Sciences Strategic Pilot Technology Special Project(A)(No.XDA14010303)Shandong Province Innovation Project(No.2017CXGC1602)Independent Innovation(No.17CX05011)。
文摘Full waveform inversion(FWI)is an extremely important velocity-model-building method.However,it involves a large amount of calculation,which hindsers its practical application.The multi-source technology can reduce the number of forward modeling shots during the inversion process,thereby improving the efficiency.However,it introduces crossnoise problems.In this paper,we propose a sparse constrained encoding multi-source FWI method based on K-SVD dictionary learning.The phase encoding technology is introduced to reduce crosstalk noise,whereas the K-SVD dictionary learning method is used to obtain the basis of the transformation according to the characteristics of the inversion results.The multiscale inversion method is adopted to further enhance the stability of FWI.Finally,the synthetic subsag model and the Marmousi model are set to test the effectiveness of the newly proposed method.Analysis of the results suggest the following:(1)The new method can effectively reduce the computational complexity of FWI while ensuring inversion accuracy and stability;(2)The proposed method can be combined with the time-domain multi-scale FWI strategy flexibly to further avoid the local minimum and to improve the stability of inversion,which is of significant importance for the inversion of the complex model.
基金supported by the National Natural Science Foundation of China under Grants No.12474370,No.12161141010 and No.T2325022by the Innovation Program for Quantum Science and Technology under Grant No.2021ZD0301500.
文摘For the requirement of quantum photonic integration in on-chip quantum information,we propose a scheme to realize quantum controlled-Z(CZ)gates through single gradient metasurface.Using its parallel beam-splitting feature,i.e.,a series of connected beamsplitters with the same splitting ratio,one metasurface can support a polarization encoding CZ gate or path encoding CZ gate,several independent CZ gates,and cascade CZ gates.Taking advantage that the path of output state is locked by the polarization of input state,path encoding CZ gates can efficiently filter out bit-flip errors coming from beam-splitting processes.These CZ gates also have the potential to detect quantum errors and generate high-dimensional entanglement through multi-degree-of-freedom correlation on metasurfaces.By integrating quantum CZ gates into a single metasurface,our results open an avenue for high-density and multifunctional integration of quantum devices.
基金supported by the National Natural Science Foundation of China(Nos.61771205 and 62071186)Natural Science Foundation of Guangdong Province(No.2015A030313388)+1 种基金Science and Technology Planning Project of Guangdong Province(Nos.2015B010128012 and 2017KZ010101)Key Laboratory Foundation of Guangdong Province,China(No.2020B1212060066)。
文摘The quantum key distribution(QKD)network is a promising solution for secure communications.In this paper,we proposed a polarization-independent phase-modulated polarization encoding module,and it can be combined with a dense wavelength division multiplexer(DWDM)to achieve multi-user QKD.We experimentally test the encoding module with a repetition rate of 62.5 MHz,and its average quantum bit error rate(QBER)is as low as 0.4%.Finally,we implement a principle verification test for simultaneous QKD for 1 to 2 users in 100 min,and the average QBER of two users under the transmission distance of 1 km and 5 km is kept below 0.8%.Due to the use of polarization encoding,the module can also realize scalable network architecture in free-space QKD systems in the future.
