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1、Entanglementofaquantumopticalellipticvortex1,2*11†AbirBandyopadhyay,ShashiPrabhakar,RavindraPratapSingh1QuantumOptics&QuantumInformationGroup,TheoreticalPhysicsDivision,PhysicalResearchLaboratory,Navrangpura,Ahmedabad–380009,India2HooghlyEngineeringandTechnologyColl
2、ege,Hooghly712103,IndiaAbstractWecalculatetheentanglementofageneralizedellipticalvortexformedbyquantizedradiationfield,usingWignerquasiprobabilitydistributionfunctionforsuchstates.Wefindacriticalsqueezingparameterabovewhichtheentanglementislessforhighervorticity,whi
3、chiscounterintuitive.Keywords:Entanglement,Quantumopticalellipticvortex.PACS:42.65.Lm,03.67.Bg,03.67.Mn,42.50.Gy,03.75.LmOCIS:270.5585,070.7425,270.6570,080.48651.IntroductionEntanglementisfundamentalindeterminingtheusefulnessofaquantumstateinquantuminformationproto
4、cols.Entangledstatesplayacentralroleinquantumkeydistribution,superdensecoding,quantumteleportation,andquantumerrorcorrection[1],whichcannotberealizedclassically.WhileamajorpartoftheeffortinquantuminformationtheoryhasbeeninthecontextofsystemswithfinitenumberofHilbert
5、spacedimensions,morespecificallythequbits,recentlytherehasbeenmuchinterestinthecanonicalcontinuouscases[2].However,Gaussianstates,whicharepartofcontinuousvariablecase,aremuchbetterstudiedandmethodshavebeendevisedtomeasuretheentanglementforsuchstates[3,4].Themeasureo
6、fentanglementforaGaussianstateisbestcharacterizedbythelogarithmicnegativity[5],aquantityevaluatedintermsofthesymplecticeigenvaluesofthecovariancematrix[4].Opticalvorticesorphasesingularitiesinthefieldoflight,describedbyanon-separabletwo-dimensionalfield,havedrawnagr
7、eatdealofattentioninthelasttwodecades[6].Becauseoftheirspecificspatialstructureandassociatedorbitalangularmomentum(OAM),theyfindavarietyofapplicationsinthefieldofopticalmanipulation[7],opticalcommunication[8],quantuminformationandcomputation[9].Foravortex,theOAMfoll
8、owsthesamenumbersasvorticityortopologicalchargeofthevortexi.e.anopticalvortexoftopologicalchargem,carriesanOAMofmħperphoton.Although,theOA
