Rewrite state in new basis - Quantum Mechanics

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SUMMARY

The discussion focuses on rewriting the quantum state |ψ⟩ = √(1/2)(|0⟩ + |1⟩) in a new basis defined by |3⟩ and |4⟩. The new basis states are given as |3⟩ = √(1/3)|0⟩ + √(2/3)|1⟩ and |4⟩ = √(2/3)|0⟩ − √(1/3)|1⟩. Participants discussed the challenges of converting between bases using Dirac notation and provided algebraic analogies to simplify the process. The solution involves rearranging the basis states to express |0⟩ and |1⟩ in terms of |3⟩ and |4⟩.

PREREQUISITES
  • Understanding of Dirac notation in quantum mechanics
  • Familiarity with quantum state representation
  • Basic knowledge of linear algebra concepts
  • Experience with basis transformations in quantum systems
NEXT STEPS
  • Study the process of basis transformation in quantum mechanics
  • Learn about orthonormal bases and their significance in quantum states
  • Explore the mathematical techniques for rearranging quantum states
  • Investigate the implications of different bases on quantum measurements
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Students and researchers in quantum mechanics, particularly those working with state transformations and Dirac notation. This discussion is beneficial for anyone seeking to deepen their understanding of quantum state representation and manipulation.

12x4
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Homework Statement


Rewrite the state |ψ⟩ = √(1/2)(|0> + |1>) in the new basis.

|3⟩ = √(1/3)|0⟩ + √(2/3)|1⟩

|4⟩ = √(2/3)|0⟩ − √(1/3)|1⟩


You may assume that |0⟩ and |1⟩ are orthonormal.

Homework Equations



The Attempt at a Solution


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I have a similar example in my notes however there is a step that I has stumped me. Annoyingly its the first one.

In my notes I have:

"""If we want to work in the basis |+⟩ and |−⟩ instead of | ↑⟩ and |↓⟩, with,

|+⟩ = (1/√2)(| ↑⟩ + | ↓⟩) & |−⟩ = (1/√ 2)(| ↑⟩ − | ↓⟩)

how would |ψ⟩ and I be written in the new basis?

Let us rearrange as:

| ↑⟩ = 1/(√2)(|+⟩ + |−⟩) & | ↓⟩ = (1/√2)(|+⟩ − |−⟩)"""

After rearranging I think that I should be able to complete the question but as it stands I can't see how to rearrange them to get |0> & |1>. Any advice would be much appreciated as really struggling with Dirac notation at the moment. Thanks 12x4
 
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You're probably just getting confused by the new notation. Consider the ordinary algebraic equations
\begin{align*}
u &= \frac{1}{\sqrt 2} x + \frac{1}{\sqrt 2} y \\
v &= \frac{1}{\sqrt 2} x - \frac{1}{\sqrt 2} y
\end{align*} How would you solve for ##x## in terms of ##u## and ##v##? You can essentially do the same thing.
 
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thanks vela, I just managed to do it with your advice.
 

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