Entangled particles and measurement

Click For Summary
SUMMARY

The discussion centers on the implications of measuring entangled particles, specifically in the context of quantum mechanics. It is established that measuring one particle of an entangled pair collapses the wave function, resulting in the loss of interference patterns. The double-slit experiment illustrates this phenomenon, where interference is lost when the position of an electron is measured due to entanglement with a photon. The consensus is that entangled particles do not exhibit interference patterns when measured, confirming the original poster's conclusions.

PREREQUISITES
  • Quantum mechanics fundamentals
  • Understanding of entangled states, specifically |Ψ>=a |0>|0> + b |1>|1>
  • Knowledge of the double-slit experiment
  • Concept of wave function collapse
NEXT STEPS
  • Research the implications of quantum entanglement on measurement theory
  • Study the role of time in quantum measurements and entanglement
  • Explore the concept of quantum erasers and their effect on interference patterns
  • Investigate the mathematical formalism of quantum states and their measurements
USEFUL FOR

Physicists, quantum mechanics students, and researchers interested in the behavior of entangled particles and the foundational principles of quantum measurement.

JK423
Gold Member
Messages
394
Reaction score
7
We know that if, for example, two particles are entangled in a state like: |Ψ>=a |0>|0> + b |1>|1>, then measuring an observable on only one of the particles it makes the interference dissapear.
But isn't it impossible to measure both particles simultaneously in order to maintain the interference?? There should be an infinitsimal time difference!
That leads me to the conclusion that if two particles get entangled then no interferences will ever appear. Would you agree?

Also, the above can explain for example why in the double slit experiment interference is lost when we try to specify the electron`s position (which slit). When the photon scatters from the electron, their interaction makes them somehow get entangled. So, when the electron hit the wall (position measurement) the interference is lost just because it`s entangled to the photon that scattered!
If the scattered photon is detected first (measurement), then its' state collapses and so does the electron`s. That means, no interference again.
Is the above description any close to reality?

And one last question! I mentioned above that in the photon-electron scattering the particles somehow get entangled. In general, when particles interact with each other, they get entangled??
 
Physics news on Phys.org
JK423 said:
We know that if, for example, two particles are entangled in a state like: |Ψ>=a |0>|0> + b |1>|1>, then measuring an observable on only one of the particles it makes the interference dissapear.
But isn't it impossible to measure both particles simultaneously in order to maintain the interference?? There should be an infinitsimal time difference!
That leads me to the conclusion that if two particles get entangled then no interferences will ever appear. Would you agree?

A couple of points. First, interference disappears for entangled photons if the possibility merely exists to determine which-slit information. It only "returns" (this is a bit too complex to get into in a paragraph) if you erase that possibility. Second, as you suggest, there is a time difference when measuring Alice and Bob pretty much no matter how you set things up.

So essentially, your conclusion is correct. Groups of entangled photons NEVER show an interference pattern directly.
 
Thanks a lot DrChinese!
If there are any other comments on the rest of the OP, they`d be welcome!
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 14 ·
Replies
14
Views
2K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 58 ·
2
Replies
58
Views
5K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K