Introduction To Quantum Mechanics
Introduction To Quantum Mechanics
3rd Edition
ISBN: 9781107189638
Author: Griffiths, David J., Schroeter, Darrell F.
Publisher: Cambridge University Press
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Chapter 4, Problem 4.65P
To determine

Construct the quadruplet and the two doublets using the notation of Equation 4.175 and 4.176.

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Answer to Problem 4.65P

Constructed the quadruplet and the two doublets using the notation of Equation 4.175 and 4.176:

The quadruplet is,

|3232=||3212=13(|+|+|)|3212=13(|+|+|)|3232=|

The doublet 1 is

|12121=12(||)|12121=12||

The doublet 2 is

|12122=16(2|+|+|)|12122=16(||+2|)

Explanation of Solution

To construct the quadruplet:

Let |3232=|

Write the expression for lowering operator for one particle, Equation 4.146

    S|=|

And,

    S|=0

For all three states,

S=S1+S2+S3

Therefore, the other states of the lowering operator is

S=S1+S2+S3

From above equations,

S|3232=S|=(|+|+|)=B3/23/2|3212=3|3212

|3212=13(|+|+|)

Solving to find |3212.

S|3212=3(|+|+|+|+|+|)=23(|+|+|)=B3/21/2|3212|3212=13(|+|+|)

Solving to find |3232.

S|3212=3(|+|+|)=3|=B3/21/2|3232

Solving further,

S|3212=3|3232|3232=|

Thus, the quadruplet is

|3232=||3212=13(|+|+|)|3212=13(|+|+|)|3232=|

To construct doublet 1:

Let |12121=12(||).

S|12121=2(|+|||)=2(||)=B1/21/2|12121=|12121

Hence,

|12121=12||

Thus, the doublet 1 is

|12121=12(||)|12121=12||

To construct doublet 2:

Let |12122=a|+b|+c| (orthogonal to |12121 and |3212).

11212|12122=12(||)(a|+b|+c|)=12(bc)=0

Since,

bc=0b=c

Similarly to find a&b,

3212|12122=13(|+|+|)(a|+b|+c|)=13(a+b+c)=0

Since,

a+b+c=0a+2b=0a=2b

For normalization,

|a|2+|b|2+|c|2=1

Substituting the relation of a,b,c in the above equation,

4|b|2+|b|2+|b|2=16|b|2=1|b|2=16b=16

The, c=16 and 1=26.

Substituting the value of a,b&c in |12122=a|+b|+c|

|12122=26|+16|+16|=16(2|+|+|)

To solve for |12122

S|12122=6(2|2|+|+|+|+|)=6(||+2|)=B1/21/2|12122=|12122

Therefore,

|12122=16(||+2|)

Thus, the doublet 2 is

|12122=16(2|+|+|)|12122=16(||+2|)

Conclusion:

Constructed the quadruplet and the two doublets using the notation of Equation 4.175 and 4.176:

The quadruplet is

|3232=||3212=13(|+|+|)|3212=13(|+|+|)|3232=|

The doublet 1 is

|12121=12(||)|12121=12||

The doublet 2 is

|12122=16(2|+|+|)|12122=16(||+2|)

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