- #1
San K
- 911
- 1
A polarizer is a device that converts a beam of electromagnetic waves (light) of undefined or mixed polarization into a beam with well-defined polarization.
by undefined do we mean 1 or 2 below?
1. we don't know the polarization (but it must be having some value of the spin) or
2. the photon does not have a definite spin yet
mixed polarization means: a mixture of defined spins? (up or down, right or left etc)
once a polarizer has defined a spin of a photon, how can one later undefine it?
for example can we undefine via having it strike a BBO crystal and allow two entangled photons to emerge with undefined spin?
thus a polarizer does two things?
1. forces undefined photons to define their state
2. a) filters (or splits) the recently defined photons (defined by the polarizer a micro micro micro micro micro micro micro micro micro second back)
2. b) filters (or splits) the "pre-defined" photons
so we have two kinds of photons. these photons are very different in terms of their state.
1. photons with defined spins. the spin will remain like that forever till it encounters things like BBO crystal
2. photons with undefined spins. the spin will remain undefined forever till it encounters things like a polarizer/QWPs etc