Demystifying Photons and Polarizers: Understanding Interaction and Measurement

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Discussion Overview

The discussion revolves around the interaction of photons with polarizers, specifically addressing the nature of photons' polarization states before and after passing through a polarizer. The scope includes conceptual understanding and theoretical implications of measurement in quantum mechanics.

Discussion Character

  • Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions whether a photon can pass through a polarizer without interaction, noting that only photons aligned with the polarizer's orientation would pass through while others would be blocked.
  • Another participant asserts that the photon's state collapses to the polarization of the polarizer upon measurement, which they describe as being labeled arbitrarily as horizontal (H) or vertical (V).
  • A participant acknowledges that a photon is not in a defined state until it reaches the polarizer, reinforcing the idea of state collapse.
  • Another participant adds that there are instances when a photon may arrive at the polarizer already in a polarized state, suggesting that the outcome depends on whether the photon is in a pure state or a superposition, with a mixed state being described as a collection of particles in unknown pure states.

Areas of Agreement / Disagreement

Participants express varying views on the nature of a photon's state prior to measurement and the implications of polarization. There is no consensus on whether a photon can be considered to have a defined state before interacting with the polarizer.

Contextual Notes

The discussion touches on the complexities of quantum states, including the definitions of pure, mixed, and superposition states, which remain unresolved and depend on specific interpretations of quantum mechanics.

cragar
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Cant we shoot a photon thorough a polarizer without having the polarizer interact with it ?
Like all the ones polarized perpendicular to it will get blocked but the ones lined up will go through. But if the particle is not in a polarized state until we measure then how does this work?
 
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It collapses to the polarization of the polarizer, which is arbitrary labeled H or V. A polarizing beam splitter passes both H and V, but in different output directions. A polarizing filter just passes V.

http://en.wikipedia.org/wiki/Polarizer
 
Ok so it is not in a state until it reaches the polarizer and it collapses it to that state.
thanks for your response.
 
cragar said:
Ok so it is not in a state until it reaches the polarizer and it collapses it to that state.
thanks for your response.

Also, there are times when it IS in a polarized state when it arrives a the polarizer. At that point, the polarization may be changed. Depends on whether it is in a pure state or a superposition. (A collection of particles in unknown pure states is called "mixed".)
 

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