Vývoj fotonů
Návrh a vývoj fotonů – kvantová teorie světla
In1901,GermanphysicistPlanck(Plank)foundtheenergydistributionlawoftheabsoluteblackbodyradiationspectrumunderthermalequilibriumconsistentwiththeexperiment.Thislawisthestartingpointforthedevelopmentofquantumtheory.Thebasisofthislawistoassumethatmatterhasdiscontinuouscharacteristicsoflightemittedandabsorbed,andthatlightisemittedorabsorbedbyafinitepart-lightquanta.
Theenergyεofthisphotonisproportionaltothevibrationfrequencyωoflight,andcanbeexpressedbythefollowingequation
Zde,JePlanck'sconstant.
WhenEinsteinpointedoutthatinadditiontoenergyε,animpulse(thedirectionofthisimpulseisconsistentwiththepropagationdirectionoflight)mustbeusedtodescribethephoton,thephotonTheexpressionhasonlygotaperfectform.
Pokud je zaveden vlnový vektork,je jeho složka rovna
whereλisthewavelength,andcosα,cosβ,cosγIsthecosineofthenormaldirectionofthelightwave,sotheimpulseformulaofthelightquantumcanbewritteninvectorform
photonaction
photonisTheelementaryparticlethattransmitselectromagneticinteractionisagaugeboson.Photonisthecarrierofelectromagneticradiation,andinquantumfieldtheory,photonisconsideredasthemediatorofelectromagneticinteraction.Comparedwithmostelementaryparticles,therestmassofaphotoniszero,whichmeansthatitspropagationspeedinvacuumisthespeedoflight.Likeotherquanta,photonshavewave-particleduality:photonscanshowthepropertiesofclassicwavessuchasrefraction,interference,anddiffraction;andtheparticlenatureofphotonscanbeprovedbythephotoelectriceffect.Photonscanonlytransmitquantizedenergy.Theyarelatticeparticlesandthemass-energyphaseofcirclequantumparticles.
Photonproperties
Aftertheestablishmentofquantumelectrodynamics,itisconfirmedthatphotonsarethemediaparticlesthattransmitelectromagneticinteractions.Chargedparticlesinteractbyemittingorabsorbingphotons.Thepairofpositiveandnegativechargedparticlescanbeannihilatedandconvertedintophotons,andtheycanalsobegeneratedinanelectromagneticfield.
Photonsareparticlesthatcarryenergyinlight.Theenergyofaphotonisproportionaltothefrequencyofthelightwave.Thehigherthefrequency,thehighertheenergy.Whenaphotonisabsorbedbyanatom,anelectrongainsenoughenergytotransitionfromtheinnerorbittotheouterorbit,andtheatomwiththeelectronictransitionchangesfromthegroundstatetotheexcitedstate.
Energie, hybnost a hmotnost fotonů. Podle rovnice hmotnosti a energie E=mc2=hν, najít< i>m=hν/c2,
Becausethephotoncannotbestationary,ithasnostationarymass.Themasshereistherelativisticmassofthephoton.
Podle teorie kvantového pole může být pár kladných a záporných částic zničen do páru vysokoenergetických gamafotonů a pár vysokoenergetických gamafotonů může také reagovat při vysokých teplotách, aby produkoval pár kladných a záporných částic.Například>>>1 5teplota< verze fotonů v obaryontech, jako jsou protony a neutrony se mohou vyskytovat.
Thepositron-negativeelectronscattering(alsocalledBha-Bhascattering)representedbyFeynmandiagram,andthewavylinerepresentstheprocessofexchangingvirtualphotons.
Viz:Speciální teorie relativity
Fromtheperspectiveofwaves,photonshavetwopossiblepolarizationstatesandthreeorthogonalwavevectorcomponents,whichdetermineFromthepointofviewofparticles,therestmassofthephotoniszero,thechargeiszero,andthehalf-lifeisinfinite.Aphotonisagaugebosonwithaspinof1,sothenumberofleptons,baryons,andsingularnumbersareallzero.
Největší hmotyfotonisstriktního lyzera,kteréjevpodstatěekvivalentnípřísnémuvztahuinverzníčtvercový vztahCoulombova zákona.Jestliženejvýšehmotnostifotografu není nula,pakCoulombůvzákonnenípřísněinverznísvorník.Všechny související klasické teorie,jako jsou kvantity magnetických teorií, jako jsou Maxwellovy sekvenční rovnice a jako Měkký foton je přísný lyzero. Z Einsteinova vztahu hmotnost-energie a vzorce fotonové energie lze horní hranici hmotnosti fotonu získat jen velmi těžko:m=hν/< i>c2
Zde jemhorní mez hmotnosti fotonu aνje frekvence jakékoli elektromagnetické vlny, což je Schumannova rezonance v ultranízkofrekvenčním pásmu. Nejnižší známá frekvence je asi 7,8 Hz (Hertz).
Thisvalueisonlytwoordersofmagnitudehigherthanthecurrentlyacceptedupperlimit.
Viz Fotony:Kanonické bosony
Photonscanbeproducedinmanynaturalprocesses,forexample:inmolecules,atomsornucleifromhighenergylevelstolowenergyPhotonsareradiatedwhenthechargeisacceleratedduringtheleveltransition,andphotonsarealsoproducedwhenparticlesandantiparticlesareannihilated;intheabove-mentionedtimereversalprocess,photonscanbeabsorbed,thatis,molecules,atomsornucleitransitionfromlowenergylevelstohighenergylevels,Thegenerationofparticleandantiparticlepairs.
Rychlost fotonů ve vakuu je rychlost světla a vztah mezi energiíEa hybnostípjep=E/c ;Vztah mezi energií a hybností částic se statickou hmotou v relativistické mechanice.
Energie a hybnost fotonisonu souvisí pouze s frekvencíνfotonu; orita souvisí pouze s vlnovou délkouλ. Tak se hybnost fotoni získá jako p=h/λ=hv/ c.
kdehse nazývá Planckova konstanta.
Aninference může být odvozena ze vzorců pro energii a hybnost fotonů
Theannihilationprocessofparticlesandtheirantiparticlesmustproduceatleasttwophotons.Thereasonisthatthetotalmomentumofthesystemcomposedofparticlesandtheirantiparticlesinthecenterofmasssystemiszero.Duetothelawofconservationofenergy,thetotalmomentumofthegeneratedphotonsmustalsobezero;becauseasinglephotonalwayshasanon-zeromomentum,thesystemOnlytwoormorephotonscanbegeneratedtosatisfythetotalmomentumofzero.Thefrequencyatwhichphotonsareproduced,thatis,theirenergy,isdeterminedbythelawofconservationofenergy-momentum(four-dimensionalmomentumconservation).Fromtheconservationofenergy-momentum,itcanbeseenthattheinverseprocessofparticleandantiparticleannihilation,thatis,theprocessoftwo-photongeneratingelectron-antielectronpairscannotbespontaneouslygeneratedinavacuum.
Photonhaswave-particleduality
Thatistosay,photonnotonlyhasthecharacteristicsofoneparticlebyoneparticle,butalsohasthevolatilitylikesoundwave.Whentimeisaninstantaneousvalue,photonspropagateintheformofparticles;whentimeisanaveragevalue,photonspropagateintheformofwaves.Thewavenatureofphotonsisprovedbythediffractionofphotons,andtheparticlenatureofphotonsisprovedbythephotoelectriceffect.
Někteří lidé výše si myslí, že je to špatně, protože dynamická hmotnost fotonu je bezero a statická hmotnost fotonu je nulová, jinak bude jeho dynamická hmotnost nekonečná. Ale jeho dynamická hmotnost existuje. Metoda výpočtu je následující: Zaprvé, protože energie fotonu s frekvencíEh zde< i>hje Planckova konstanta), hmotnost půdy lze získat ze vzorce hmotnost-energie:m=E/c2 =hv/c2kdec2představuje čtverec rychlosti světla. Tuto metodu jako první navrhl Einstein.
PhotonTheory
Photonshavespeed,energy,momentum,mass,andcondensation.Itisimpossibleforphotonstostandstill.Photonscanbecomeothersubstances(suchasapairofpositiveandnegativeelectrons),butenergyandmomentumareconserved.[Withinafewnanoseconds)controlthepathandpolarizationofphotonswiththesamewavelengthasthecurrentopticalcommunicationnetwork.Thenewphotoniccircuitcanbeintegratedintotheexistingopticalcommunicationnetwork,therebysignificantlyimprovingtheperformanceofthenetwork.Thelatestresearchhastakenasteptowardstherealizationofopticalquantumcommunication.
ScientistsfromtheUniversityofBristol,Heriot-WattUniversity,andtheKavliInstituteforNanoscienceintheNetherlandspublishedthisstudyontherapidcontrolofthepathandpolarizationofsinglephotonsinthelatestissueofPhysicalReview"LearningExpress"magazine.
Whentheystudiedaquantumopticaldevicecomposedofcircuits,theyfoundthatasinglephotonwouldmovethroughthesecircuits,andthesecircuitscouldalsobereconfiguredtochangethepathandpolarizationdirectionofthephoton.However,suchquantumopticalcircuitscannotquicklymanipulatesingle-photonandmulti-photonstates.Inordertosolvethisproblem,theyusedalithiumniobatewaveguidethathasbeenproventobecapableofrapidmanipulationinexistingcommunicationmodulators,andprovedthatapplyingavoltagetothewaveguideneartheelectrodecanquicklymanipulateoneortwowavelengthsof1550nanometers.Thequantum(includingpathandpolarization)stateoflightcomposedofaphotonisexactlythewavelengthusedintheexistingcommunicationnetwork.
DamienBonooftheUniversityofBristol,wholedtheresearch,said:“Inthisexperiment,wedemonstratedtwocircuitconfigurations.Eachcircuitconfigurationleadstoadifferentquantumstate.Configurationonlytakesafewnanoseconds.Inpreviousexperiments,thecircuitcanbereconfiguredeveryfewseconds.Communicationnetworksuseswitchesmadeofthesametechnologytotransmitinformationbytesencodedbyopticalpulseseveryday.Intermsoftheabove,suchaswitchcanalsobeusedatthesingle-photonlevel."
Bonosaid:"Uptonow,themanipulationofthequantumstateoflightonthechiphasalwaysreliedonheaters,whichcanbeusedasaslowphaseshifter.Thelatestresearchshowsthatthelithiumniobatewaveguidecanuseacompletelydifferentmethodtomanipulatethequantumstateoflightmorequickly.Wecannotonlyopenandclosetheopticalpackettosendtraditionalinformationaccordingtotheprescribedroute,butalsoQuicklyprocessandmanipulatethequantumstateoflight."
Scientistspointedoutthatbeingabletoquicklycontrolthepolarizationandpathofasinglephotononasingleplatformisveryimportanttobasicquantumscienceandquantumtechnology.Bonosaidthatthelithiumniobatematerialsusedtomakethesedevicescanalsorandomlygeneratephotons.Inaddition,single-photondetectorswithsuperconductivitycanalsobeintegratedonsuchachip.Atechnologyplatformthatcombineslightsources,circuits,anddetectorsthatcanrandomlygeneratephotonscanbeusedinthefollowingareas:multiplephotonsourcesareusedtoobtainreliablesingle-photonsources,quantumrelaysrequiredforlong-distancequantumcommunications,Quantumkeydistributionusedinquantumcryptography,etc.
Inthepast,someold-fashionedradiosusedelectronictubes,andtheyhadtobewarmedupeachtimetheyworked.Withtheapplicationofsemiconductortubes,thepreheatingtimeissaved.Nowadays,similaradvanceshavetakenplaceinthefieldofopticalquantummodulationequipment.Inthepast,aheaterwasusedtoreconfigurethecircuitinafewseconds,anditwaspossibletoswitchtoanothercircuitinafewnanoseconds.Theuseoflithiumniobateasawaveguidedeviceisacommontechnicalmethodinthemodemera.Butwhowouldhavethoughtthataslightchangeinthemediocrephotoelectricconversionequipmentcouldhelpthemostcutting-edgeopticalquantumcommunicationresearchtomakeabreakthrough?Withtheintegrationoflightsources,circuits,anddetectors,theworkloadofquantumcommunicationresearcherscanbereducedalot.
Související události
Profesoři Přírodovědecké a technologické univerzity Huazhong znovu definují horní hranici klidové hmotnosti fotonů
ProfessorsofHuazhongUniversityofScienceandTechnologyredefinetheupperlimitofphotonrestingmassSomepeopleintheindustrybelievethatthezerorestmassofphotonsisoneofthebasicassumptionsofclassicalelectromagnetictheory.Butsomescientistsbelievethatphotonsmayhaverestmass.Iftheexperimentfinallydetectsthatthephotonhasarestmass,thensomeclassicaltheorieswillhavetochange.
IntheAmerican"PhysicalReviewLetters"(PhysicalReviewLetters),aspecialarticleintroduced:"AnewexperimentcompletedbyChinesescientistLuoJunandothersshowsthatunderanycircumstances,Therestmassofaphotonwillnotexceed10totheminus54kilogram.Thisresultis1/20ofthepreviouslyknownupperlimitofphotonmass.”LuoJunandhiscolleaguesusedanovelexperimentalmethodtoexperimentinacave.Theupperlimitoftherestingmassofphotonsintheroomhasbeenfurtherincreasedbyatleastanorderofmagnitude.
Itisreportedthatifthephotonhasastaticmass,althoughitwillnotaffectpeople’sdailylife,theconsequenceswillbefundamental-forexample,thespeedoflightwillchangewiththechangeofwavelength,andLightwaveswillbeabletoproducelongitudinalvibrationsjustlikesoundwaves.