(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A system in a state [itex]\frac{1}{\sqrt{2}}(\left<\phi\right| + \left<\psi\right|)[/itex] undergoes an interaction with a second system (which is initially in [itex]\left<\alpha\right|[/itex]) and ands up in an entangled state [itex]\frac{1}{\sqrt{2}}\left(\left\langle\phi\right| \otimes \left\langle\alpha\right| + \left\langle\psi\right|\otimes \left\langle\beta\right|\right)[/itex]. Find a unitary operator that will perform that interaction/measurement.

The respective states in each space are orthonormal, and φ and ψ form a complete basis.

2. Relevant equations

I assume the linearity of tensor products is relevant. Other than that, I'm really not sure what.

3. The attempt at a solution

I don't know nearly enough about entanglement or unitary operators here. An entangled state means one that isn't separable, I know. A unitary operator U satisfies U*U = UU* = I. From there... I don't know.

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# Quantum entanglement and measurement operator

Can you offer guidance or do you also need help?

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