作者	P.Busch/等
出版社
出版时间	1999-04-01

特色：

片断：PrologueThetheoryofquantummechanicsonHilbertspacehasbeenthebasisoffruitfulanddeepresearchintovirtuallyallbranchesofphysicsfornearlyseventyyears.Thereseemstobenoinstanceofaconflictbetweentheoreticalpredictionsandexperimentalresults.Inviewofthissuccessitisremarkablethatafewconceptualproblemshaveresistedanyattemptedresolutionevenuntilnow.Someofthembecametractableoncetheprobabilisticstructureofquantummechanicswasprop-erlyappreciatedinitsfullgenerality.Gleason'stheoremandtheintroductionofthenotionofanobservableasapositivcoperatorvalued(POV)measurewerethecrucialstepsinthisdevelopment.Interestingly,thelatterdiscoverywasmadein-dependentlyinavarietyofratherdisparateareasofquantumphysics,motivationsrangingfromfoundationalintereststofairlypracticalneeds.Thiswidescopeoftheconceptofpovmeasurealreadydemonstratesitsstatusasanintegralpartofthebasicstructureofquantummechanics.Thetraditionalnotionofobservablesasself-adjointoperatorsconstitutesaspecialcase,representedbyprojectionoperatorvalued(PV,orspectral)measures.TheincorporationofPOVmeasuresintothequantumvocabularyhasnotonlyopenedupnewwaysofapproachinglongstandingtheoreticalpuzzles,italsogaverisetoanelaborationofquantummeasurementtheoryintoaconceptuallysoundandmathematicallyrigorous,powerfultoolforanalysingphysicalexperiments.Theensuingresearchactivitieshaveledtoavarietyofreviewsandmonographsdealingwithsuchdiversetopicsasprobabilisticandstatisticalaspectsofquantumtheory,quantumestimationanddetection,quantumtheoryofopensystems,photoncount-ingtheory,orquantummechanicsonphasespace.Muchofthisworkisdoneonahightechnicallevelandhasthuscontributedtosettingnewstandardsofrigourforinvestigationsinthefoundationsofquantumphysics.AtthesametimethePOVmeasureapproachtoquantumobservableshasgraduallyinducedaproba-bilisticreformulationofquantumtheorythatisconceptuallysimplerandclosertoexperimentalpracticethanthetraditionalapproach.Thepresentbookisaresultoftwointimatelyrelatedlinesofresearcheffortsthattookplaceinthepastdecade.Ontheonehandquantummeasurementtheoryhasfoundmanifoldsuccessfulapplicationsleadingtonewinsightsintheanalysisoffundamentalexperiments.OntheotherhandconsiderableprogresshasbeenmadeinworkingouttheoperationalconditionsneededforassociatingPOVmeasureswithpropertiesofphysicalsystems.Bothdevelopmentshavecontributedtofullyappreciatingtherelevanceofquantummechanicsasatheoryofindividualobjects.Theneedforsucharealisticinterpretationofquantumtheoryisstrikinglyevidentinthesedayswhereoneiswitnessingworldwideactivitiesincarryingoutexcitingexperimentswithsinglemicrosystemssuchasatoms,ions,neutrons,orphotons-experimentswhichformerlycouldonlybeconceivedasthoughtexperiments.Ourprimaryconcernistwofold.Firstwewishtodemonstratetheamazingcapabilitiesofthequantumformalismifappliedinitsfull-fledgedprobabilisticform.TheadvantagesofPOVmeasuresandofmeasurementtheory,takenastoolsofinvestigationintothequantumworld,willbeillustratedinseveralstepsandondifferentlevelsofsophistication.YetthenotionofaPOVmeasuremustitselfbesubjectedtoameasurementtheoreticalanalysisinordertoelucidateitsphysicalmeaning.Referencetothisdoubleroleofthemeasurementtheoryistheultimatepurposeofthetenn'operational'appearinginthebooktitle.TheunderstandingofPOVmeasuresasrepresentingobservablepropertiesofaphysicalsystemwillbebasedonarealistic,individualinterpretationofquantumtheory.Accordingtothisinterpretationquantummechanicsdescribesphysicalsystemsexistingindependentlyoncetheyhavebeenpreparedoridentifiedbyob-servation.Evidenceforthepresenceofasystemmaybeascertainedbymeansofdeterminingitsreal(oractual)properties;andusingidealmeasurementsthiscanbeachievedwithouttherebychangingthesysteminanyway.Ingeneral,however,apropertywillbenonobjective(orpotential)andmaybeactualisedthroughmeas-urement.Suchrepeatablemeasurementscanthusbeused