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56 个结果
  • 简介:Two-dimensionalmaterialsaregeneratinggreatinterestduetotheiruniqueelectricalandopticalproperties.Inparticular,transitionmetaldichalcogenidessuchasmolybdenumdisulfide(MoS2)areattractivematerialsduetotheexistenceofadirectbandgapinthemonolayerlimitthatcanbeusedtoenhancenonlinearopticalphenomena,suchasRamanspectroscopy.Here,wehaveinvestigatedfour-wavemixingprocessesinbulkMoS2usingamultiplexcoherentanti-StokesRamanspectroscopysetup.Theobservedfour-wavemixingsignalhasaresonanceatapproximately680nm,correspondingtotheenergyoftheAexcitonictransitionofMoS2.Thisresonancecanbeattributedtotheincreasedthird-ordernonlinearsusceptibilityatwavelengthsneartheexcitonictransition.ThisphenomenoncouldopenthepathtousingMoS2asasubstrateforenhancingfour-wavemixingprocessessuchascoherentanti-StokesRamanspectroscopy.

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  • 简介:一个光陷井能在在一个光洞嵌入的一个ultracold原子系统由一块轻地被印,是众所周知的,并且由三块不同的协调的地开车。在光洞共存的三块地中,有一块强烈控制地,经由创造与联系Rabi频率的平方成正比的力量的一个周期的光栅栏的导致electromagnetically的透明性,和另一块地导致巨大的克尔非线性。在这,管理探查域的繁殖的非线性的方程的工作elliptic-soliton答案被考虑,与形成有明确的量数字的一个分离系列的光soliton火车的可能的产生上的强调。这个问题被对待假定周期的光栅栏的二种不同类型并且考虑否定并且detunings(detuning在上面或在回声下面)的正号。结果预言在自我阶段和跨阶段的调整非线性之间的比赛产生不同的量数字描绘的时间的soliton火车模式的一个富有的家庭。

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  • 简介:Thispaperproposesanexperimentallyfeasibleschemeforimplementingquantumdensecodingoftrapped-ionsystemindecoherence-freestates.Asthephasechangesduetotimeevolutionofcomponentswithdifferenteigenenergiesofquantumsuperpositionarecompletelyfrozen,quantumdensecodingbasedonthismodelwouldbeperfect.TheschemeisinsensitivetoheatingofvibrationalmodeandBellstatescanbeexactlydistinguishedviadetectingtheionicstate.

  • 标签: 量子密度编码 截留离子 自由脱离状态 量子学
  • 简介:这篇论文与p拉普拉斯算符处理非线性的单个四点的边界价值问题的一个班的多重积极解决方案的存在:在哪儿φ(x)=|x|p−2x,p>1,(t)可能在t=是单个的0或t=1。由使用Leggett威廉,修理的固定的点定理和Schauder削尖定理,为存在的足够的条件多重(至少三)上述四点的边界值问题的积极答案被提供。说明获得的结果的重要性的一个例子也被给。

  • 标签: 非线性类 拉普拉斯算子 固定点定理 非线性代数方程
  • 简介:Wedemonstratetheefficientgenerationofcoherentlightinafour-leveldouble-cascadeatomicmediumbycontinuous-wavelow-intensitylaserradiation.Wederivethecorrespondingexplicitanalyticalexpressionsforthegeneratedfour-wavemixing(FWM)field.DependenciesoftheintensityofthegenerateFWMfieldonthepropagationdistance,ontheinput-waveintensity,andonthephotondetuningareinvestigated.Toconclude,wealsogiveabriefdiscussionontheexperimentalrealizationoftheproposedscheme.

  • 标签: 连续波 四波混合 原子相干 干涉效应 非线性光学
  • 简介:Inthispaper,airsideheattransferandpressuredropcharacteristicsoftwelvethree-rowplatefin-and-tubeheatexchangercoresoffourtypesoffinconfigurationshavebeenexperimentallyinvestigated.TheheattransferandfrictionfactorcorrelationsforthetwelvecoresareprovidedinawiderangeofReynoldsnumber.ItisfoundthatintherangeofReynoldsnumbertested.theNusseltnumberoftheslottedfinsurfaceisthelargestandthatoftheplainplatefinisthelowestwhiletheNusseltnumbersoftwotypesofwavyfinsaresomewhereinbetween.

  • 标签: 热传导 热交换器 压强下降
  • 简介:Weproposeapositionsensorlesscontrolschemeforafour-switch,three-phasebrushlessDCmotordrive,basedonthezerocrossingpointdetectionofphaseback-EMFvoltagesusingnewlydefinederrorfunctions(EFs).Thecommutationin-stantsare30°afterdetectedzerocrossingpointsoftheEFs.DevelopedEFshavegreatermagnituderatherthanphaseorlinevoltagessothatthesensorlesscontrolcanworkatalowerspeedrange.Moreover,EFshavesmoothtransitionsaroundzerovoltagelevelthatreducesthecommutationerrors.EFsarederivedfromthefilteredterminalvoltagesvaoandvbooftwolow-passfilters,whichareusedtoeliminatehighfrequencynoisesforcalculationoftheaverageterminalvoltages.Thefeasibilityoftheproposedsensorlesscontrolisdemonstratedbysimulationandexperimentalresults.

  • 标签: 无刷直流电动机 四开关逆变器 传感控制器 反电势 数字信号处理
  • 简介:BasedonageneralanalysisofGreenfunctionsinthereal-timethermalfieldtheory,wehaveproventhatthefour-pointamputatedfunctionsinanNJLmodelinthefermionbubblediagramapproximationbehavelikeusualtwo-pointfunctions.WeexpoundthethermaltransformationsofthematrixpropagatorsforascalarboundstateintheFFbasisandintheRAbasisrespectively.Theresultingphysicalcausal,advancedandretardedpropagatorsarerespectivelyidenticaltocorrespondingonesderivedintheimaginary-timeformalism,andthisshowsonceagainthecompleteequivalenceofthetwoformalismsofthermalfieldtheoryonthediscussedproblemintheNJLmodel.

  • 标签: 自发对称破缺 四点函数 二点函数 NJL模型
  • 简介:Thespin-polarizedlinearconductancespectrumandcurrent-voltagecharacteristicsinafour-quantum-dotringembodiedintoAharonov-Bohm(AB)interferometerareinvestigatedtheoreticallybyconsideringalocalRashbaspin-orbitinteraction.Itshowsthatthespin-polarizedlinearconductanceandthecorrespondingspinpolarizationareeachafunctionofmagneticfluxphaseatzerobiasvoltagewithaperiodof2π,andthatHubbardUcannotinfluencetheelectrontransportpropertiesinthiscase.Whenadjustingappropriatelythestructuralparameterofinter-dotcouplinganddot-leadcouplingstrength,theelectronicspinpolarizationcanreachamaximumvalue.Furthermore,byadjustingthebiasvoltagesappliedtotheleads,thespin-upandspin-downcurrentsmoveinoppositedirectionsandpurespincurrentexistsintheconfigurationspaceinappropriatesituations.Basedonthenumericalresults,suchamodelcanbeappliedtothedesignofaspinfilterdevice.

  • 标签: 自旋轨道相互作用 自旋极化输运 量子点 干涉仪 基础 电子输运性质
  • 简介:AgraphissaidtobeK1,4-freeifitdoesnotcontainaninducedsubgraphisomorphictoK1,4.Letkbeanintegerwithk≥2.WeprovethatifGisaK1,4-freegraphoforderatleast11k-10withminimumdegreeatleastfour,thenGcontainskvertex-disjointcopiesofK1+(K1∪K2).

  • 标签: 不相交 最小度 FREE图 顶点 吉隆坡 曲线图