Math Problem Statement

Suppose a vector in H1 is |v(1)⟩ = 1/√2 |1(1)⟩ + I/√2 |2(1)⟩ while a vector in H2 is |v(2)⟩ = 1/√3 |1(2)⟩ + √2/√3 |2(2)⟩. Show that each of these vectors are normalized.

Solution

To show that each vector is normalized, we need to verify that their norms (or magnitudes) are equal to 1. For a vector v|v⟩ to be normalized, it must satisfy the condition:

vv=1\langle v | v \rangle = 1

Normalization of v(1)|v(1)⟩

The vector v(1)|v(1)⟩ is given by:

v(1)=121(1)+i22(1)|v(1)⟩ = \frac{1}{\sqrt{2}} |1(1)⟩ + \frac{i}{\sqrt{2}} |2(1)⟩

Now, compute the inner product v(1)v(1)\langle v(1) | v(1) \rangle:

v(1)v(1)=(121(1)+i22(1))(121(1)+i22(1))\langle v(1) | v(1) \rangle = \left( \frac{1}{\sqrt{2}} \langle 1(1)| + \frac{-i}{\sqrt{2}} \langle 2(1)| \right) \left( \frac{1}{\sqrt{2}} |1(1)⟩ + \frac{i}{\sqrt{2}} |2(1)⟩ \right)

Expanding this product:

v(1)v(1)=121(1)1(1)+i21(1)2(1)i22(1)1(1)+122(1)2(1)\langle v(1) | v(1) \rangle = \frac{1}{2} \langle 1(1) | 1(1) \rangle + \frac{i}{2} \langle 1(1) | 2(1) \rangle - \frac{i}{2} \langle 2(1) | 1(1) \rangle + \frac{1}{2} \langle 2(1) | 2(1) \rangle

Since the basis vectors 1(1)|1(1)⟩ and 2(1)|2(1)⟩ are orthonormal, we have:

1(1)1(1)=1,2(1)2(1)=1,1(1)2(1)=2(1)1(1)=0\langle 1(1) | 1(1) \rangle = 1, \quad \langle 2(1) | 2(1) \rangle = 1, \quad \langle 1(1) | 2(1) \rangle = \langle 2(1) | 1(1) \rangle = 0

Thus:

v(1)v(1)=121+0+0+121=1\langle v(1) | v(1) \rangle = \frac{1}{2} \cdot 1 + 0 + 0 + \frac{1}{2} \cdot 1 = 1

Hence, v(1)|v(1)⟩ is normalized.

Normalization of v(2)|v(2)⟩

The vector v(2)|v(2)⟩ is given by:

v(2)=131(2)+232(2)|v(2)⟩ = \frac{1}{\sqrt{3}} |1(2)⟩ + \frac{\sqrt{2}}{\sqrt{3}} |2(2)⟩

Now, compute the inner product v(2)v(2)\langle v(2) | v(2) \rangle:

v(2)v(2)=(131(2)+232(2))(131(2)+232(2))\langle v(2) | v(2) \rangle = \left( \frac{1}{\sqrt{3}} \langle 1(2)| + \frac{\sqrt{2}}{\sqrt{3}} \langle 2(2)| \right) \left( \frac{1}{\sqrt{3}} |1(2)⟩ + \frac{\sqrt{2}}{\sqrt{3}} |2(2)⟩ \right)

Expanding this product:

v(2)v(2)=131(2)1(2)+231(2)2(2)+232(2)1(2)+232(2)2(2)\langle v(2) | v(2) \rangle = \frac{1}{3} \langle 1(2) | 1(2) \rangle + \frac{\sqrt{2}}{3} \langle 1(2) | 2(2) \rangle + \frac{\sqrt{2}}{3} \langle 2(2) | 1(2) \rangle + \frac{2}{3} \langle 2(2) | 2(2) \rangle

Again, since the basis vectors 1(2)|1(2)⟩ and 2(2)|2(2)⟩ are orthonormal, we have:

1(2)1(2)=1,2(2)2(2)=1,1(2)2(2)=2(2)1(2)=0\langle 1(2) | 1(2) \rangle = 1, \quad \langle 2(2) | 2(2) \rangle = 1, \quad \langle 1(2) | 2(2) \rangle = \langle 2(2) | 1(2) \rangle = 0

Thus:

v(2)v(2)=131+0+0+231=1\langle v(2) | v(2) \rangle = \frac{1}{3} \cdot 1 + 0 + 0 + \frac{2}{3} \cdot 1 = 1

Hence, v(2)|v(2)⟩ is normalized.

Conclusion:

Both v(1)|v(1)⟩ and v(2)|v(2)⟩ are normalized, as their inner products with themselves yield 1.


Would you like further clarification or details?

Here are some related questions:

  1. What are orthonormal vectors, and how are they used in quantum mechanics?
  2. How do inner products work in the context of Hilbert spaces?
  3. Why is normalization important for quantum states?
  4. How can we generalize this process for vectors with more than two components?
  5. What is the physical interpretation of these normalized vectors?

Tip: In quantum mechanics, normalization ensures that the total probability of finding a system in any state sums to 1.

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Math Problem Analysis

Mathematical Concepts

Quantum Mechanics
Vector Spaces
Linear Algebra
Hilbert Spaces

Formulas

⟨v | v⟩ = 1 (normalization condition)
|v(1)⟩ = 1/√2 |1(1)⟩ + i/√2 |2(1)⟩
|v(2)⟩ = 1/√3 |1(2)⟩ + √2/√3 |2(2)⟩
⟨v(1) | v(1)⟩ = ⟨v(2) | v(2)⟩ = 1 (inner product calculation)

Theorems

Normalization of vectors
Orthonormality of basis vectors in Hilbert space

Suitable Grade Level

Undergraduate (Quantum Mechanics or Linear Algebra)