Past exam of the short options paper of the physics Prelims of the University of Oxford / 2022 / S03 / 3 / b

Table of contents
- Solution b

Solution

Measuring the first qubit applies

P_{0} = ∣0 ⟩ ⟨ 0∣ \otimes I

or

P_{1} = ∣1 ⟩ ⟨ 1∣ \otimes I

. The Born rule gives

p_{0} = ∣ α ∣^{2} + ∣ β ∣^{2}, p_{1} = ∣ γ ∣^{2} + ∣ δ ∣^{2} = 1 - p_{0} .

The normalized conditional quantum states are

∣ ψ_{0} ⟩ = \frac{α ∣00 ⟩ + β ∣01 ⟩}{p _{0}}, ∣ ψ_{1} ⟩ = \frac{γ ∣10 ⟩ + δ ∣11 ⟩}{p _{1}} .

Each expression applies only when its denominator is nonzero; an impossible outcome has no defined conditional state.

 Ancestors (12)

 View article source

 Discussion (0)

There are no discussions about this article yet.

 Articles by others on the same topic (0)

There are currently no matching articles.

  See all articles in the same topic Create my own version