简介:Two-dimensionalmaterialsaregeneratinggreatinterestduetotheiruniqueelectricalandopticalproperties.Inparticular,transitionmetaldichalcogenidessuchasmolybdenumdisulfide(MoS2)areattractivematerialsduetotheexistenceofadirectbandgapinthemonolayerlimitthatcanbeusedtoenhancenonlinearopticalphenomena,suchasRamanspectroscopy.Here,wehaveinvestigatedfour-wavemixingprocessesinbulkMoS2usingamultiplexcoherentanti-StokesRamanspectroscopysetup.Theobservedfour-wavemixingsignalhasaresonanceatapproximately680nm,correspondingtotheenergyoftheAexcitonictransitionofMoS2.Thisresonancecanbeattributedtotheincreasedthird-ordernonlinearsusceptibilityatwavelengthsneartheexcitonictransition.ThisphenomenoncouldopenthepathtousingMoS2asasubstrateforenhancingfour-wavemixingprocessessuchascoherentanti-StokesRamanspectroscopy.
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。
简介:Thispaperproposesanexperimentallyfeasibleschemeforimplementingquantumdensecodingoftrapped-ionsystemindecoherence-freestates.Asthephasechangesduetotimeevolutionofcomponentswithdifferenteigenenergiesofquantumsuperpositionarecompletelyfrozen,quantumdensecodingbasedonthismodelwouldbeperfect.TheschemeisinsensitivetoheatingofvibrationalmodeandBellstatescanbeexactlydistinguishedviadetectingtheionicstate.
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简介:Wedemonstratetheefficientgenerationofcoherentlightinafour-leveldouble-cascadeatomicmediumbycontinuous-wavelow-intensitylaserradiation.Wederivethecorrespondingexplicitanalyticalexpressionsforthegeneratedfour-wavemixing(FWM)field.DependenciesoftheintensityofthegenerateFWMfieldonthepropagationdistance,ontheinput-waveintensity,andonthephotondetuningareinvestigated.Toconclude,wealsogiveabriefdiscussionontheexperimentalrealizationoftheproposedscheme.
简介:Inthispaper,airsideheattransferandpressuredropcharacteristicsoftwelvethree-rowplatefin-and-tubeheatexchangercoresoffourtypesoffinconfigurationshavebeenexperimentallyinvestigated.TheheattransferandfrictionfactorcorrelationsforthetwelvecoresareprovidedinawiderangeofReynoldsnumber.ItisfoundthatintherangeofReynoldsnumbertested.theNusseltnumberoftheslottedfinsurfaceisthelargestandthatoftheplainplatefinisthelowestwhiletheNusseltnumbersoftwotypesofwavyfinsaresomewhereinbetween.
简介:Weproposeapositionsensorlesscontrolschemeforafour-switch,three-phasebrushlessDCmotordrive,basedonthezerocrossingpointdetectionofphaseback-EMFvoltagesusingnewlydefinederrorfunctions(EFs).Thecommutationin-stantsare30°afterdetectedzerocrossingpointsoftheEFs.DevelopedEFshavegreatermagnituderatherthanphaseorlinevoltagessothatthesensorlesscontrolcanworkatalowerspeedrange.Moreover,EFshavesmoothtransitionsaroundzerovoltagelevelthatreducesthecommutationerrors.EFsarederivedfromthefilteredterminalvoltagesvaoandvbooftwolow-passfilters,whichareusedtoeliminatehighfrequencynoisesforcalculationoftheaverageterminalvoltages.Thefeasibilityoftheproposedsensorlesscontrolisdemonstratedbysimulationandexperimentalresults.
简介:BasedonageneralanalysisofGreenfunctionsinthereal-timethermalfieldtheory,wehaveproventhatthefour-pointamputatedfunctionsinanNJLmodelinthefermionbubblediagramapproximationbehavelikeusualtwo-pointfunctions.WeexpoundthethermaltransformationsofthematrixpropagatorsforascalarboundstateintheFFbasisandintheRAbasisrespectively.Theresultingphysicalcausal,advancedandretardedpropagatorsarerespectivelyidenticaltocorrespondingonesderivedintheimaginary-timeformalism,andthisshowsonceagainthecompleteequivalenceofthetwoformalismsofthermalfieldtheoryonthediscussedproblemintheNJLmodel.
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.