Solution Manual for Modern Quantum Mechanics, 2nd Edition

Unlock the answers to every textbook problem with Solution Manual for Modern Quantum Mechanics, 2nd Edition, making studying more efficient and effective.

Henry Martinez
Contributor
4.2
42
7 months ago
Preview (16 of 112 Pages)
100%
Purchase to unlock

Page 1

Solution Manual for Modern Quantum Mechanics, 2nd Edition - Page 1 preview image

Loading page ...

2Chapter One1.AC{D, B}=ACDB+ACBD,A{C, B}D=ACBD+ABCD,C{D, A}B=CDAB+CADB, and{C, A}DB=CADB+ACDB. ThereforeAC{D, B}+A{C, B}DC{D, A}B+{C, A}DB=ACDB+ABCDCDAB+ACDB=ABCDCDAB= [AB, CD]In preparing this solution manual, I have realized that problems 2 and 3 in are misplacedin this chapter. They belong in Chapter Three. The Pauli matrices are not even defined inChapter One, nor is the math used in previous solution manual.– Jim Napolitano2.(a)Tr(X) =a0Tr(1) +￿￿Tr(σ￿)a￿= 2a0sinceTr(σ￿) = 0. AlsoTr(σkX) =a0Tr(σk) +￿￿Tr(σkσ￿)a￿=12￿￿Tr(σkσ￿+σ￿σk)a￿=￿￿δk￿Tr(1)a￿= 2ak. So,a0=12Tr(X) andak=12Tr(σkX).(b) Just do the algebra to finda0= (X11+X22)/2,a1= (X12+X21)/2,a2=i(X21+X12)/2, anda3= (X11X22)/2.3.Since det(σ·a) =a2z(a2x+a2y) =|a|2, the cognoscenti realize that this problemreally has to do with rotation operators. From this result, and (3.2.44), we writedet￿exp￿±iσ·ˆnφ2￿￿= cos￿φ2￿±isin￿φ2￿and multiplying out determinants makes it clear that det(σ·a￿) = det(σ·a). Similarly, use(3.2.44) to explicitly write out the matrixσ·a￿and equate the elements to those ofσ·a.With ˆnin thez-direction, it is clear that we have just performed a rotation (of the spinvector) through the angleφ.4.(a)Tr(XY)￿a￿a|XY|a￿=￿a￿b￿a|X|b￿￿b|Y|a￿by inserting the identity operator.Then commute and reverse, soTr(XY) =￿b￿a￿b|Y|a￿￿a|X|b￿=￿b￿b|Y X|b￿=Tr(Y X).(b)XY|α￿=X[Y|α￿] is dual to￿α|(XY), butY|α￿ ≡|β￿is dual to￿α|Y≡ ￿β|andX|β￿is dual to￿β|Xso thatX[Y|α￿] is dual to￿α|YX. Therefore (XY)=YX.(c) exp[if(A)] =￿aexp[if(A)]|a￿￿a|=￿aexp[if(a)]|a￿￿a|(d)￿aψa(x￿)ψa(x￿￿) =￿a￿x￿|a￿￿x￿￿|a￿=￿a￿x￿￿|a￿￿a|x￿￿=￿x￿￿|x￿￿=δ(x￿￿x￿)5.For basis kets|ai￿, matrix elements ofX|α￿￿β|areXij=￿ai|α￿￿β|aj￿=￿ai|α￿￿aj|β￿.For spin-1/2 in the| ±z￿basis,￿+|Sz= ¯h/2￿= 1,￿−|Sz= ¯h/2￿= 0, and, using (1.4.17a),￿±|Sx= ¯h/2￿= 1/2. Therefore|Sz= ¯h/2￿￿Sx= ¯h/2|.=12￿1100￿6.A[|i￿+|j￿] =ai|i￿+aj|j￿ ￿= [|i￿+|j￿] so in general it is not an eigenvector, unlessai=aj.That is,|i￿+|j￿is not an eigenvector ofAunless the eigenvalues are degenerate.

Page 2

Page 3

Page 4

Page 5

Page 6

Page 7

Page 8

Page 9

Page 10

Page 11

Page 12

Page 13

Page 14

Page 15

Page 16

Preview Mode

This document has 112 pages. Sign in to access the full document!

Study Now!

XY-Copilot AI
Unlimited Access
Secure Payment
Instant Access
24/7 Support
Document Chat

Document Details

Related Documents

View all