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Implementation of a multiple round quantum dense coding using nuclear magnetic resonance

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Science china(Physics,Mechanics & Astronomy) 2005年第6期48卷 706-715页

作者： ZHANG Jingfu1, XIE Jingyi2, WANG Chuan1, DENG Zhiwei3, LU Zhiheng4, & LONG Guilu1,5 1. Key Laboratory For quantum information and Measurements of MOE, Department of Physics, tsinghua university, beijing 100084.china 2. Department of Materials Science and Engineering, beijing Normal university, beijing 100875, china 3. Testing and Analytical center, beijing Normal university, beijing 100875,china 4. Department of Physics, beijing Normal university, beijing 100875, china 5. Key Laboratory For atomic and Molecular Nanosciences, tsinghua university, beijing 100084.china Key Laboratory For quantum information and Measurements Department of Physics Tsinghua University Beijing 100084 China Department of Materials Science and Engineering Beijing Normal University Beijing 100875 China Testing and Analytical center Beijing Normal University Beijing 100875 China Department of Physics Beijing Normal University Beijing 100875 China Key Laboratory for Atomic and Molecular Nanosciences Tsinghua University Beijing 100084 China

A multiple round quantum dense coding scheme based on the quantum phase estimation algorithm is proposed and implemented in a three qubit nuclear magnetic resonance (NMR) quantum computer. Using an m + 1 qubit system, Bob can transmit one of 2m+1 messages to Alice, through manipulating only one qubit and exchanging it between Alice and Bob for m rounds. The information capacity is enhanced to m + 1 bits as compared to m bits in a classical scheme. The scheme has been demonstrated in NMR system, and the experimental results show a good agreement between theory and experiment.

关键词： quantum dense coding, multiple round, nuclear magnetic resorance

Learning interactions among multi-channel sequences with dynamical influence models

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Science china(information Sciences) 2010年第7期53卷 1336-1344页

作者： ZHANG WeiDong, CHEN Feng & XU WenLi Department of Automation, National Laboratory for information Science and Technology, tsinghua university, beijing 100084. china Department of Automation National Laboratory for Information Science and Technology Tsinghua University Beijing China

Many real applications involve simultaneous recording and analysis of multi-channel information sources. Learning and modeling the interactions among channels is the kernel step to analyze and recognize system characteristics. This paper presents a model that learns the dynamical influence among multi-channel sequences. The model, dynamical influence model, permits functional roles of individual channels to change and models the changing influence strength between channels. By querying the values of influence factors, we can recognize the functional role of each channel qualitatively and learn about to what extent the chains influence each other quantitatively at any time. The experimental results on synthetic data and application of multi-person interaction recognition show that our model is reliable and effective.

关键词： multi-channel processing dynamical interaction influence model activity recognition

Truncation error calculation based on Richardson extrapolation for variable-step collaborative simulation

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Science china(information Sciences) 2011年第6期54卷 1238-1250页

作者： ZHANG HeMing 1 , LIANG SiLu 2 , SONG ShiJi 1 & WANG HongWei 3 1 Department of Automation, TNList, tsinghua university, beijing 100084. china 2 Computer and information Management center, tsinghua university beijing 100084. china 3 Engineering Design Centre, Engineering Department, Cambridge university, Cambridge CB2 1PZ, UK Department of Automation TNList Tsinghua University Beijing China Computer and information Management center Tsinghua University Beijing China Engineering Design Centre Engineering Department Cambridge University Cambridge UK

Collaborative simulation is an effective approach to performing simulation analysis for complex systems by integrating models developed for different engineering disciplines. Collaborative simulation issues include the modeling of coupled multidisciplinary systems, and the simulation running time integration of these models that are solved parallelly. Estimation of the local truncation error of coupling models is the key to solve multidisciplinary collaborative simulation problem, which is actually used to restrict the simulation step. This paper presents a variable-step method based on Richardson extrapolation for calculating the local truncation error to solve collaborative simulation problem of multidisciplinary coupling models. Formulas for estimating the local truncation error are derived through theoretical analysis by using integration methods and interpolation technologies, respectively. The simulation experiments are illustrated to validate the accuracy and efficiency of proposed collaborative simulation algorithm in comparison with the usual combinative algorithm.

关键词： multidisciplinary systems collaborative simulation variable-step algorithm error estimation

Electric-stimulus rate encoding algorithm of Mandarin tonal information in cochlear implant

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Progress in Natural Science:Materials International 2006年第12期16卷 1315-1321页

作者： GUAN Tian~1, GONG Qin~1 and YE Datian~2**(1. Department of Biomedical Engineering, tsinghua university, beijing 100084. china 2. Research center of Biomedical Engineering, Graduate School at Shenzhen, tsinghua university, Shenzhen 518055, china) Department of Biomedical Engineering Tsinghua University Beijing 100084 China Research center of Biomedical Engineering Graduate School Shenzhen Tsinghua University Shenzhen 518055 China

The modern multi-channel cochlear implants usually extract and encode the temporal envelope cues. This kind of algorithms can hardly satisfy the users who speak tonal languages, such as Mandarin. Many studies have tried to enhance the recognition ability of Mandarin through encoding tonal information and made suggestions to frequency-modulate the fixed pulse-rate carrier with the extracted tonal information based on the rate-pitch theory in electric hearing. However, how to encode and deliver the tonal information such as F_0by changing electric-stimulus rate has not got further study in clinical electric-stimulus mode. The present paper focuses on this matter by piecewise calculating the appreciable electric-stimulus rates. Then an electric-stimulus encoding algorithm of Mandarin tone is brought forward and testified through acoustic simulations. Such conclusion can be drawn that this algorithm of electric-stimulus rate could convey tonal information well and help to enhance the Mandarin speech recognition ability.

关键词： cochlear implant tone fundamental frequency electric-stimulus rate.

Development of a model to generate a risk map in a building fire

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Science china(Technological Sciences) 2010年第10期53卷 2739-2747页

作者： CHU YanYan, ZHANG Hui, SHEN ShiFei, YANG Rui & QIAO LiFeng center for Public Safety Research, Department of Engineering Physics, tsinghua university, beijing 100084. china center for Public Safety Research Department of Engineering Physics Tsinghua University Beijing China

Fire simulations and sensors are widely used in building fires,various data such as temperature,CO and CO2 concentration,visibility can be obtained by sensors and sensor-based simulation. It is important to generate a risk map based on such data so that we can use it to estimate safety of the building. In this paper,we propose a method to generate a dynamical,integrated risk map using sensor readings in a building fire. Such risk evaluation model is developed using similarity comparison between the space state and dangerous state by a likelihood distance calculating and data grouping from a two-step cluster method. The risk evaluation model considers the integrated influence on the occupants in the zone from high temperature,lack of oxygen,toxic and harmful gases and shows the relative fire risk map at certain time. Based on the simulation study,it is proved that multi-factor fire risk analysis would be more objective and accurate than single factor and two-factor risk analysis and the fire risk evaluation model can generate a risk map and provide the classification information and the whole building risk statistic results to support evacuation command and control.

关键词： building fire risk map cluster analysis fire simulation

Eavesdropping in a quantum secret sharing protocol based on Grover algorithm and its solution

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Science china(Physics,Mechanics & Astronomy) 2010年第3期53卷 491-495页

作者： HAO Liang1, LI JunLin1 & LONG GuiLu1,2 1Key Laboratory for Atomic and Molecular NanoSciences and Department of Physics, tsinghua university, beijing 100084. china 2tsinghua National Laboratory for information Science and Technology, beijing 100084. china Key Laboratory for Atomic and Molecular NanoSciences and Department of Physics Tsinghua University Beijing China tsinghua National Laboratory for information Science and Technology Beijing China

A detailed analysis has showed that the quantum secret sharing protocol based on the Grover algorithm (Phys Rev A, 2003, 68: 022306) is insecure. A dishonest receiver may obtain the full information without being detected. A quantum secret-sharing protocol is presents here, which mends the security loophole of the original secret-sharing protocol, and doubles the information capacity.

关键词： quantum secret sharing Grover algorithm quantum cryptography quantum search algorithm

A Novel Network Management Model Based on XML for Service and Resource

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计算机工程 2002年第S1期28卷 77-81页

作者： ZHANG JinxiangWU JianpingWANG Jilong(Network Research center of tsinghua university, beijing 100084.china, jxzhang@***) Network Research center of tsinghua university Beijing 100084China j xzhang ***

XML can allow for the interchange of data between management applications using different information models. Furthermore, CORBA technique is increasingly used in the management of service and resource in the heterogeneous network environment. As the scheme of information arrangement of CORBA is flat file style, which handles querying, deleting, and insertinginformation inefficiently, this paper puts forward a novel network management model based on XML in the domain of the management of CERNET (china Education and Research Network), which has used a tree structure of managed objects arrangement to provide efficient operation on managed objects. In addition, arrangement, definition, implementation and finding schemes for CORBA managed objects using XML are also given by the tree structure, and thus can arrange and retrieve managed objects efficiently.

关键词： XMLCORBANetwork managementModel

Two mode photon bunching effect as witness of quantum criticality in circuit QED

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Science china(Physics,Mechanics & Astronomy) 2009年第12期52卷 1898-1905页

作者： AI Qing1,WANG YingDan2,LONG GuiLu1,3 & SUN ChangPu4 1 Department of Physics,tsinghua university,beijing 100084.china 2 Department of Physics,university of Basel,Klingelbergstrasse 82,4056 Basel,Switzerland 3 tsinghua National Laboratory for information Science and Technology,beijing 100084.china 4 Institute of Theoretical Physics,Chinese Academy of Sciences,beijing 100080,china Department of Physics Tsinghua University Beijing China Department of Physics University of Basel Basel Switzerland tsinghua National Laboratory for information Science and Technology Beijing China Institute of Theoretical Physics Chinese Academy of Sciences Beijing China

We suggest a scheme to probe critical phenomena at a quantum phase transition (QPT) using the quantum correlation of two photonic modes simultaneously coupled to a critical system. As an experimentally accessible physical implementation,a circuit QED system is formed by a capacitively coupled Josephson junction qubit array interacting with one superconducting transmission line resonator (TLR). It realizes an Ising chain in the transverse field (ICTF) which interacts with the two magnetic modes propagating in the TLR. We demonstrate that in the vicinity of criticality the originally independent fields tend to display photon bunching effects due to their interaction with the ICTF. Thus,the occurrence of the QPT is reflected by the quantum characteristics of the photonic fields.

关键词： quantum phase transition photon bunching circuit QED

Effects of disinhibition on spatiotemporal pattern of neuronal first recruitment in neuronal networks

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Progress in Natural Science:Materials International 2009年第5期19卷 615-621页

作者： Liangbin Pana,b,c,1, Xindong Songa,b,c,1, Guangxin Xiang a,b,c, Jing Zhua,b,c, Jing Cheng a,b,c,d,a Medical Systems Biology Research center, tsinghua university School of Medicine, beijing 100084. china b Department of Biological Sciences and Biotechnology, tsinghua university, beijing 100084. china c National Engineering Research center for beijing Biochip Technology, 18 Life Science Parkway, beijing 102206, china d State Key Laboratory of Biomembrane and Membrane Biotechnology, tsinghua university, beijing 100084. china Medical Systems Biology Research center Tsinghua University School of Medicine Beijing 100084 China Department of Biological Sciences and Biotechnology Tsinghua University Beijing 100084 China National Engineering Research center for beijing Biochip Technology 18 Life Science Parkway Beijing 102206 China State Key Laboratory of Biomembrane and Membrane Biotechnology Tsinghua University Beijing 100084 China

The propagation of neuronal activities is a key feature to understanding information processing in networks. The analysis based on first-spikes of bursts in turn plays an important role in the research of neuronal activity propagation. Our focus here is to investigate how spatiotemporal patterns of neuronal first-spikes are affected by disinhibition. Multi-electrode arrays were used to record stimulation-evoked bursts of multiple neurons in randomly cultured neuronal networks. Both the precise timing of and the rank relationships between first-spikes were analyzed. Compared with evoked bursts in the network’s native state, the precise first-spike latencies in its dis-inhibited state are more consistent and the propagation of its bursting activities is much faster. Additional points of interest are that disinhibited neuronal networks can be evoked to generate stable and distinguishable neuronal first recruitment spatiotemporal patterns specific to the stimulation site, and that the disinhibition may cause the original spatiotemporal patterns to change in a heterogeneous manner with regards to different propagation pathways.

关键词： Neuronal recruitment Spatiotemporal pattern Disinhibition Network Multi-electrode array