复旦量子力学讲义qmchapter.ppt

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1、Chapter 4Path Integral,4.1 Classical action and the amplitude in Quantum Mechanics,Introduction:how to quantize?Wave mechanics h Schrdinger equ.Matrix mechanics h commutator Classical Poisson bracket Q.P.B.Path integral h wave function,4.1 Classical action and the amplitude in Quantum Mechanics,Basi

2、c ideaInfinite orbitsDifferent orbits have different probabilities,4.1 Classical action and the amplitude in Quantum Mechanics,A particle starting from a certain initial state may reach the final state through different possible orbits with different probabilities,4.1 Classical action and the amplit

3、ude in Quantum Mechanics,Classical action,4.1 Classical action and the amplitude in Quantum Mechanics,4.1 Classical action and the amplitude in Quantum Mechanics,4.1 Classical action and the amplitude in Quantum Mechanics,4.1 Classical action and the amplitude in Quantum Mechanics,Free particle,4.1

4、Classical action and the amplitude in Quantum Mechanics,4.1 Classical action and the amplitude in Quantum Mechanics,Linear oscillator,4.1 Classical action and the amplitude in Quantum Mechanics,4.1 Classical action and the amplitude in Quantum Mechanics,4.1 Classical action and the amplitude in Quan

5、tum Mechanics,4.1 Classical action and the amplitude in Quantum Mechanics,Amplitude in quantum mechanicsAll paths,not only just one path from a to b,have contributionsThe contributions of all paths to probability amplitude are the same in module,but different in phasesThe contribution of the phase f

6、rom each path is proportional to S/h,where S is the action of the corresponding path,4.1 Classical action and the amplitude in Quantum Mechanics,In summary:the quantization scheme of the path integral supposes that the probability P(a,b)of the transition is,4.1 Classical action and the amplitude in

7、Quantum Mechanics,4.1 Classical action and the amplitude in Quantum Mechanics,h appears as a part of the phase factorQ.M.C.M while h 0,4.1 Classical action and the amplitude in Quantum Mechanics,Classical limit:S/h 1Quickly oscillate,4.1 Classical action and the amplitude in Quantum Mechanics,S depe

8、nds on xa,xb considerably,4.2 Path integral,How to calculate K(b,a),4.2 Path integral,Key:the variable in the integration is a function This is a functional integral,4.2 Path integral,4.2 Path integral,4.2 Path integral,4.2 Path integral,4.2 Path integral,4.2 Path integral,The functional integration

9、 of two adjacent events,4.2 Path integral,4.2 Path integral,4.2 Path integral,4.2 Path integral,4.2 Path integral,Free particlesAdditional normalization factor,4.2 Path integral,4.2 Path integral,4.2 Path integral,4.2 Path integral,4.2 Path integral,4.2 Path integral,de Broglie relation,4.2 Path int

10、egral,4.2 Path integral,4.2 Path integral,4.2 Path integral,4.2 Path integral,Normalization factor,4.2 Path integral,4.2 Path integral,4.3 Gauss integration,A type of functional integration which can easily be calculated,4.3 Gauss integration,4.3 Gauss integration,4.3 Gauss integration,4.3 Gauss int

11、egration,Conclusion:The Gauss integration only depends on the second homogeneous function of y and derivative of y,4.3 Gauss integration,Normalization factor of the linear oscillator,4.3 Gauss integration,4.3 Gauss integration,4.3 Gauss integration,Forced oscillator situation,4.3 Gauss integration,4

12、.3 Gauss integration,Any potential,4.3 Gauss integration,4.4 Path integral and the Schrdinger equation,Path integral Schrdinger equationPath integral wave mechanics matrix mechanics,4.4 Path integral and the Schrdinger equation,1D free particle,4.4 Path integral and the Schrdinger equation,4.4 Path

13、integral and the Schrdinger equation,4.4 Path integral and the Schrdinger equation,4.4 Path integral and the Schrdinger equation,With effective potential,4.4 Path integral and the Schrdinger equation,4.4 Path integral and the Schrdinger equation,4.4 Path integral and the Schrdinger equation,4.4 Path

14、 integral and the Schrdinger equation,4.4 Path integral and the Schrdinger equation,4.4 Path integral and the Schrdinger equation,3D Schrdinger equation,4.4 Path integral and the Schrdinger equation,4.4 Path integral and the Schrdinger equation,4.4 Path integral and the Schrdinger equation,4.4 Path

15、integral and the Schrdinger equation,4.4 Path integral and the Schrdinger equation,4.5 The canonical form of the path integral,4.5 The canonical form of the path integral,4.5 The canonical form of the path integral,4.5 The canonical form of the path integral,4.5 The canonical form of the path integral,4.5 The canonical form of the path integral,4.5 The canonical form of the path integral,4.5 The canonical form of the path integral,4.5 The canonical form of the path integral,4.5 The canonical form of the path integral,Conclusion:canonical form Lagrange form,