Do un-entangled photons exist?

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In summary, in various QM experiments, after select event(s) have occured, the photon becomes un-entangled from its twin and is usually entangled with the apparatus used to measure it. However, upon detection, the photon may become dis/un-entangled with its twin, but remains entangled with the apparatus.
  • #1
San K
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in the various QM experiments:

after select event(s) have occured, we assume collapse of wave function and the photon becomes un-entangled from its twin.

however does this un-entangled photon almost simultaneously get entangled with some other part of existence/universe/experimental apparatus?

is there any such thing as being un-entangled?
 
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  • #2
San K said:
in the various QM experiments:

after select event(s) have occured, we assume collapse of wave function and the photon becomes un-entangled from its twin.

however does this un-entangled photon almost simultaneously get entangled with some other part of existence/universe/experimental apparatus?

is there any such thing as being un-entangled?

Usually we would say the photon is entangled with the apparatus used to measure it, and had the other photon not been detected yet, entanglement between the apparatus and partner photon would exist.
 
  • #3
StevieTNZ said:
Usually we would say the photon is entangled with the apparatus used to measure it, and had the other photon not been detected yet, entanglement between the apparatus and partner photon would exist.

thanks StevieTNZ, are you suggestion b (not a) below?

a) the photon gets entangled with the apparatus upon detection and looses its entanglment with its twin photon

b) the photon is already entangled with the apparatus and get dis/un-entangled upon detection
 
  • #4
Yes, I would be going with (b).

The entanglement between the two photons (A and B), although a photon has been destroyed, has not been broken. Thereafter, entanglement exists between photon B and the apparatus used to measure photon A.
 

1. Do un-entangled photons exist?

The answer to this question is still a topic of debate among scientists. Some studies suggest that un-entangled photons do exist, while others argue that they cannot exist due to the laws of quantum mechanics.

2. What is entanglement in photons?

Entanglement in photons is a phenomenon in which two or more photons become connected in a way that their physical properties are correlated, regardless of the distance between them. This means that any changes made to one of the photons will affect the other, even if they are separated by vast distances.

3. How are entangled photons created?

Entangled photons can be created through a process called spontaneous parametric down-conversion, in which a high-energy photon is split into two lower-energy photons that are entangled with each other.

4. What are the practical applications of entangled photons?

Entangled photons have shown potential in various applications, such as quantum cryptography, quantum teleportation, and quantum computing. They could also be used in future technologies for secure communication and high-speed data transfer.

5. Can entangled photons be used for faster-than-light communication?

No, entangled photons cannot be used for faster-than-light communication. While changes made to one entangled photon will instantly affect the other, this does not violate the speed of light as no information is being transmitted between them. The laws of physics still apply, and information cannot travel faster than the speed of light.

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