Quick question on Quantum Entanglement

Click For Summary

Discussion Overview

The discussion revolves around Quantum Entanglement, specifically focusing on the implications of measuring the spin of entangled particles, the concept of wave function collapse, and the nature of subsequent measurements. Participants explore theoretical aspects and practical implications of these concepts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that measuring the x-axis spin of an electron and obtaining +1 implies the other particle must have spin -1.
  • Another participant agrees that if the same measurement is repeated, the same result should be obtained, although they acknowledge this may be an oversimplification.
  • A different participant argues that measuring once breaks the entangled state, necessitating a new set of test particles, thus introducing the probabilistic nature of quantum mechanics.
  • One participant explains that if the spin is measured along the same axis multiple times, the result will remain consistent, but measuring along a different orthogonal axis will return probabilistic results.
  • Another participant references the Stern-Gerlach experiment to illustrate the behavior of spin measurements and the effects of different measurement orientations.

Areas of Agreement / Disagreement

Participants express differing views on the implications of measuring entangled particles, particularly regarding the breaking of entanglement and the nature of subsequent measurements. No consensus is reached on these points.

Contextual Notes

There are unresolved assumptions regarding the nature of wave function collapse and the conditions under which entanglement is preserved or broken. The discussion also highlights the complexity of measuring quantum states and the dependence on measurement orientation.

Who May Find This Useful

This discussion may be of interest to students and enthusiasts of quantum mechanics, theoretical physics, and those exploring the foundational concepts of quantum entanglement and measurement theory.

Mr.Illusion
Messages
6
Reaction score
0
I'm sorry for the trouble, but I was hoping you guys could help me understand something about Quantum Entanglement.

So if I measure the x-axis spin of an electron and get +1, then that implies the the other particle must have spin -1, correct? Also, what if I measure the spin of the particle, 6 times in a row? Will I continue to get the same spin of the particle or will the spin still be random? I'm guess that as soon as I measure the spin the first time, the wave function collapses and I am left with a definite spin.
 
Physics news on Phys.org
Mr.Illusion said:
I'm sorry for the trouble, but I was hoping you guys could help me understand something about Quantum Entanglement.

So if I measure the x-axis spin of an electron and get +1, then that implies the the other particle must have spin -1, correct? Also, what if I measure the spin of the particle, 6 times in a row? Will I continue to get the same spin of the particle or will the spin still be random? I'm guess that as soon as I measure the spin the first time, the wave function collapses and I am left with a definite spin.

Yup, that's it. You ask the same question, you get the same answer. (OK, maybe I oversimplified that one.)
 
Mr.Illusion said:
I'm sorry for the trouble, but I was hoping you guys could help me understand something about Quantum Entanglement.

So if I measure the x-axis spin of an electron and get +1, then that implies the the other particle must have spin -1, correct? Also, what if I measure the spin of the particle, 6 times in a row? Will I continue to get the same spin of the particle or will the spin still be random? I'm guess that as soon as I measure the spin the first time, the wave function collapses and I am left with a definite spin.

You are right in the first, but in measuring once you break the entangled state, and need a new set of test particles. Now you are stuck with the probabilistic nature of QM as you measure unique pair, after unique pair.
 
Geigerclick said:
You are right in the first, but in measuring once you break the entangled state, and need a new set of test particles. Now you are stuck with the probabilistic nature of QM as you measure unique pair, after unique pair.

Ah, so I guess that's why you can't send information instantaneously using Quantum Entanglement. Thanks for the help btw. I'm going to be visiting this forum more in hopes to better understanding Physics/Quantum Physics.
 
Mr.Illusion said:
Ah, so I guess that's why you can't send information instantaneously using Quantum Entanglement. Thanks for the help btw. I'm going to be visiting this forum more in hopes to better understanding Physics/Quantum Physics.

From what I've read, Dr. Chinese is the well deserved guru of entanglement, and welcome to PF!
 
Thank you, Geigerclick. I am actually going for my Ph.D in Mathematics (Almost finished with undergrad now). Mathematics is easily the most appealing of the Sciences to me; of course, Quantum Mechanics and Astrophysics are next. I really want to be a Theoretical Physicist one day, and I think there is no better way to start on that journey than here.
 
Mr.Illusion said:
I'm sorry for the trouble, but I was hoping you guys could help me understand something about Quantum Entanglement.

So if I measure the x-axis spin of an electron and get +1, then that implies the the other particle must have spin -1, correct? Also, what if I measure the spin of the particle, 6 times in a row? Will I continue to get the same spin of the particle or will the spin still be random? I'm guess that as soon as I measure the spin the first time, the wave function collapses and I am left with a definite spin.

If you subsequently measure the spin along the same axis it will be the same each time. You only return to probabilistic results if you try to measure spin along a different orthogonal axis (spin in x,y,z directions cannot be simultaneously fixed)

You can demonstrate this by passing electrons through multiple filters arranged at different orientations in a Stern-Gerlach experiment. (Eg 50% will pass through the first "spin up" filter, but subsequently 100% of those will pass through another "spin up" filter)

eg http://www.upscale.utoronto.ca/PVB/Harrison/SternGerlach/SternGerlach.html

(The x-spin entanglement will be broken on the first measurement, it may be possible to measure in such a way that spin entanglement along the other orthogonal axes remains intact, DrC may have a reference)
 

Similar threads

High School Trivial quantum entanglement question (from a rookie)
  • · Replies 1 ·
Replies
1
Views
393
Undergrad Does entanglement always conserve something?
  • · Replies 9 ·
Replies
9
Views
2K
High School Quantum Entanglement information transmission idea to knock down....
  • · Replies 41 ·
2
Replies
41
Views
6K
High School Quantum entanglement and simultaneity
  • · Replies 4 ·
Replies
4
Views
3K
Graduate Is entanglement also for time-like intervals?
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad Measuring electron spin and measuring entangled electron spin
  • · Replies 12 ·
Replies
12
Views
2K
High School Entangled particle decoherence question
  • · Replies 4 ·
Replies
4
Views
2K
High School Question about Bell's inequalities and 3-particle entanglement
  • · Replies 14 ·
Replies
14
Views
2K
Undergrad Do Entangled Quantum Particles Remain Aligned After Initial Preparation?
  • · Replies 40 ·
2
Replies
40
Views
3K
Undergrad EPR in Bohm formulation
  • · Replies 45 ·
2
Replies
45
Views
4K