Detection of a Quantum Measurement

[chrisphd]

Suppose it is known that a photon has diagonal polarisation (e.g. it has just passed through a diagonal slit), then Alice comes along and measures the photon using a horizontal/vertical polarisation basis. So, I believe there is a 50% chance she will get a horizontal result and 50% chance she will obtain a vertical result.

Now Bob comes along and also knows the particle has passed through the diagonal slit, but he is unaware that Alice has already made a measurement using a horizontal/vertical basis. Is there an experiment Bob can do to check if the particle's polarisation has been measured?

Thanks

 

[DrChinese]

Suppose it is known that a photon has diagonal polarisation (e.g. it has just passed through a diagonal slit), then Alice comes along and measures the photon using a horizontal/vertical polarisation basis. So, I believe there is a 50% chance she will get a horizontal result and 50% chance she will obtain a vertical result.

Now Bob comes along and also knows the particle has passed through the diagonal slit, but he is unaware that Alice has already made a measurement using a horizontal/vertical basis. Is there an experiment Bob can do to check if the particle's polarisation has been measured?

Thanks

No in this case, and also generally no.

 

[sweet springs]

Hello.

No in this case, and also generally no.

Measurement of Alice decreases percentage of Bob's finding diagonal polarized photon to 50%, doesn't it?