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Gothican
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In Brian Greene's book 'The Fabric of the Cosmos' he introduces an experiment called the "delayed-choice quantum eraser". This was really a magnificent experiment at first sight but pretty unclear when I was done reading the results.
The experiment basically goes like this:
In each path that the photon can go through towards the detector are positioned photon splitters (called down-converters), that take photons as input and produce two photons, each with half the energy.
One photon (called the signal photon) continues toward the detector, and the second (called the idler photon) goes through a different path:
in this path the photon has a 50% chance of being detected (and then we will know the path the original photon went through), and 50% percent chance of being lost (with the result of us never knowing which path the original photon took).
The result is perfect correlation between the interference-pattern signal photons and the undetected idler ones, and vice-versa.
That's it. for those who didn't understand it fully can read this article:
http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser"
Now, let's say we delay the measurement of the idler photon until after the signal one goes through - if the signal photon already decided upon it's state (having made an interference pattern by going through both slits, or choosing only one of the slits and making up two lines of the detector), then how can it know if we will decide to take away the 50-50 chance of it's idler photon getting detected, and directly decide to detect it or not?
Thanks in advance,
Gothican
The experiment basically goes like this:
In each path that the photon can go through towards the detector are positioned photon splitters (called down-converters), that take photons as input and produce two photons, each with half the energy.
One photon (called the signal photon) continues toward the detector, and the second (called the idler photon) goes through a different path:
in this path the photon has a 50% chance of being detected (and then we will know the path the original photon went through), and 50% percent chance of being lost (with the result of us never knowing which path the original photon took).
The result is perfect correlation between the interference-pattern signal photons and the undetected idler ones, and vice-versa.
That's it. for those who didn't understand it fully can read this article:
http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser"
Now, let's say we delay the measurement of the idler photon until after the signal one goes through - if the signal photon already decided upon it's state (having made an interference pattern by going through both slits, or choosing only one of the slits and making up two lines of the detector), then how can it know if we will decide to take away the 50-50 chance of it's idler photon getting detected, and directly decide to detect it or not?
Thanks in advance,
Gothican
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