苏汝铿高等量子力学讲义

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1、Chapter2ManyBodyProblem§2.1SecondquantizationTheidenticalparticlescannotbedistinguished§2.1SecondquantizationTheessenceoftheidenticalprincipleisthatthestateofasystemshouldbedescribedintermsoftheparticlenumberinacertainquantumstateandthemany-bodyproblemshoul

2、dbediscussedintheparticlenumberrepresentationinsteadoftheoriginalcoordinaterepresentation§2.1SecondquantizationWeneedtointroducethecreationandtheannihilationoperatorstodealwithvariousprobleminthemany-bodysystem§2.1SecondquantizationBosesystem§2.1Secondquanti

3、zation§2.1Secondquantization§2.1Secondquantization§2.1Secondquantization§2.1Secondquantization§2.1Secondquantization§2.1Secondquantization§2.1Secondquantization§2.1Secondquantization§2.1Secondquantization§2.1SecondquantizationDiscussionsThewavefunctionisalre

4、adysymmetricnkistheparticlenumberoperatorofkstate§2.1Secondquantization§2.1Secondquantization§2.1SecondquantizationSecondquantization§2.1Secondquantization§2.1Secondquantization§2.1Secondquantization§2.1Secondquantization§2.1SecondquantizationForFermions§2.1

5、Secondquantization§2.1Secondquantization§2.1Secondquantization§2.2Hartree-ForkmeanfieldapproximationKey:two-bodyproblem“one-bodyproblem”+“meanfield”Example:Freeelectrongasinthemetal§2.2Hartree-ForkmeanfieldapproximationScreeningCoulombpotentialPositivecharg

6、ebackgroundcancelsk=0part§2.2Hartree-Forkmeanfieldapproximation§2.2Hartree-Forkmeanfieldapproximation§2.2Hartree-Forkmeanfieldapproximation§2.2Hartree-Forkmeanfieldapproximation§2.2Hartree-Forkmeanfieldapproximation§2.2Hartree-Forkmeanfieldapproximation§2.2H

7、artree-ForkmeanfieldapproximationSpineffect§2.2Hartree-Forkmeanfieldapproximation§2.2Hartree-Forkmeanfieldapproximation§2.2Hartree-Forkmeanfieldapproximation§2.3SuperconductivetheoryExperimentalresults1908K.OnnesLiquidhelium1911Hg:Tc=4.2K1933MeissnereffectB=

8、01986Muller,BednorzHighTcHeatcapacityCs~exp(-Δ/kBT)Δ~energygapIsotropiceffectTcM^1/2=const.§2.3SuperconductivetheoryFrohlischHamiltonian:e-p-einteractione-eattractionCooperpair:BCSTheory(Variati