How Do Photons Entangle Electrons?

In summary, when two free electrons, initially not entangled in spin or position-momentum, have a photon scattered near them in a way that is indistinguishable, they become entangled in spin. This is due to the key property of indistinguishability. However, this process is not practical for long distance entanglement experiments due to the difficulties in producing entangled particles and the potential loss of spin due to interaction with photons.
  • #1
LarryS
Gold Member
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Say we have a system consisting of two electrons, traveling freely, that are not initially entangled, either in spin or in position-momentum.

Then, because of their electric fields, a photon is emitted and absorbed between the two electrons.

Are the electrons now guaranteed to be at least partially entangled in position-momentum?
 
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  • #2
referframe said:
Say we have a system consisting of two electrons, traveling freely, that are not initially entangled, either in spin or in position-momentum.

Then, because of their electric fields, a photon is emitted and absorbed between the two electrons.

Are the electrons now guaranteed to be at least partially entangled in position-momentum?

Interesting question. They are not guaranteed to be entangled, not even partially.

that said...I know very little about it, will find out more. looking forward to some great answers from the forum.
 
  • #3
If you look for a process that can produced entangled particles, a natural one is to take a pair of electrons and separate them passively in a spatial manner without using a magnetic field. Then their spins are entangled (opposite to each other in any direction of measurement). Still it is not used for experiments at long distance because it is not practical to transport electrons and they can lose their spin by interaction with photons that are usually present in the form of thermic radiation (does anyone know at which speed for given temperatures ?). Also it may be hard to produce as pairs of electrons are present in atoms but don't easily get out. Shooting away the kernel of an helium atom is possible but, well, not easy. Experiments were done with entangled photons but I personally don't know the production method.

Then, it is useless to discuss partial entanglements as quantum theory does not distinguish a blurred entanglement from a classical correlation : a entangled pair of electrons produced as above that has 1/3 probability to be preserved and 2/3 probability to be blurred (replaced by uncorrelated random spins) is the same quantum system as a classical correlated pair produced by a 1/3 probability of having been produced by a classical correlation in each of the 3 dimensions. In other words, by throwing a dice to decide if the spins are (up,down), (down,up), (right,left), (left,right), (face,back) or (back,face).
 
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  • #4
referframe said:
Say we have a system consisting of two electrons, traveling freely, that are not initially entangled, either in spin or in position-momentum.

Then, because of their electric fields, a photon is emitted and absorbed between the two electrons.

Are the electrons now guaranteed to be at least partially entangled in position-momentum?

Not sure what you mean by a photon being emitted and absorbed by electrons. Free electrons are not bound systems, and so do not have excited states that can absorb photons.

But if you mean that a photon is scattered off the electrons, then the key property which causes them to become entangled is that something is "indistinguishable". Meaning, if a photon scatters near both electrons (within the wavelength) such that it is not possible to tell which of the two electrons it scattered off of, then they become entangled.
 
  • #5
Zarqon said:
But if you mean that a photon is scattered off the electrons, then the key property which causes them to become entangled is that something is "indistinguishable". Meaning, if a photon scatters near both electrons (within the wavelength) such that it is not possible to tell which of the two electrons it scattered off of, then they become entangled.

Interesting. I've never heard of this explanation of entanglement before. Where can I read about this explanation?
 

FAQ: How Do Photons Entangle Electrons?

1) How is entanglement created?

Entanglement is created when two or more quantum particles interact in a way that their states become correlated. This can occur through a variety of mechanisms, such as through a measurement or by sharing a common origin.

2) What is the role of quantum superposition in creating entanglement?

Quantum superposition, or the ability of a quantum particle to exist in multiple states simultaneously, is a key factor in creating entanglement. When two or more particles are entangled, their states are in a superposition of all possible combinations of states, until a measurement is made and the system collapses into a single state.

3) Can entanglement be created between particles that are not in close proximity?

Yes, entanglement can be created between particles that are not in close proximity. This is known as remote entanglement and can occur through a process called quantum teleportation, where the entangled particles share information instantaneously regardless of distance.

4) What are some practical applications of entanglement?

Entanglement has several potential practical applications, including quantum computing, quantum cryptography, and quantum teleportation. It could also potentially be used for secure communication and precision measurements.

5) Can entanglement be created artificially in a laboratory setting?

Yes, scientists can create entanglement artificially in a laboratory setting through controlled interactions between quantum particles. This allows for the study and manipulation of entangled systems, which is crucial for advancing our understanding of quantum mechanics and developing practical applications.

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