How to Measure Entangled Photons in the 45/135 Basis with Wave Plates and PBS?

In summary, the conversation discusses the use of 22.5 wave plates and PBS in the H/V basis to measure two photons in the 45/135 basis. This is done using entanglement and the resulting measurements can determine whether the photon passed a 45 degree or 135 degree test. The question at the end asks about determining the basis when measuring four entangled photons.
  • #1
StevieTNZ
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In regards to measuring two photons in the 45/135 basis using 22.5 wave plates and PBS orientated in the H/V basis:

Is it with the entanglement |H>|V> - |V>|H>, with the wave plates:
H -> 45
V -> 135
so
|45>|135> - |135>|45>
And back again using a PBS:
|H>|V> - |V>|H>

So getting |H> at the PBS indicates that the photon passed a '45 degree test'? Likewise with |V> indicating the photon was tested in the |135> polarisation, and it 'passed'?

When we measure in the 45/135 basis with four photons entangled as |H>|V>|V>|H>-|V>|H>|H>|V>, how do we tell with the PBS whether we subjected each photon to a test in 45 or 135 basis, when |H>|V>|V>|H> could be |135>|45>|135>|45> or |45>|135>|45>|45>?
 
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  • #2
@StevieTNZ did you find any more insight on this topic?
 

1. What is entanglement?

Entanglement is a quantum phenomenon where two or more particles become connected in a way that their states are dependent on each other, even when separated by large distances. This means that if one particle's state is measured, the state of the other particle will instantly be known, regardless of how far apart they are.

2. How does entanglement work?

Entanglement is based on the principle of superposition, where particles exist in multiple states at the same time. When two particles interact, they become entangled and share a single state, even when separated. This means that measuring one particle will instantly determine the state of the other particle, no matter how far apart they are.

3. What is a wave plate?

A wave plate, also known as a retardation plate, is an optical device used to manipulate the polarization of light. It consists of a thin, transparent material with a specific crystal structure that can alter the phase of light passing through it. This allows for the control of the polarization state of light, which is important in many applications such as quantum entanglement experiments.

4. How are wave plates used in entanglement experiments?

Wave plates are used in entanglement experiments to manipulate the polarization state of photons. By altering the polarization of one entangled particle, the state of the other particle will also change instantaneously, regardless of the distance between them. This allows for the testing and verification of the entanglement phenomenon.

5. What are some practical applications of entanglement and wave plates?

Entanglement and wave plates have important applications in quantum computing, quantum cryptography, and quantum teleportation. They also have potential uses in communication and sensing technologies, as well as in medical imaging and precision measurements. Additionally, the study of entanglement and wave plates has led to a better understanding of the fundamental principles of quantum mechanics.

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