Unraveling the Mystery of Quantum Eraser - Help Needed!

In summary, the conversation discusses the concept of a quantum eraser and how it works by adding polarized lenses to a two-slit interference pattern creator. The interference pattern disappears when the lenses are added, but reappears when a 50/50 lens is used. The conversation also touches on the idea that the photon can only be in one state at a time and how this relates to the concept of measurement in quantum physics. Ultimately, the conversation raises questions about the misunderstanding of the "can't measure" rule and its implications on the understanding of quantum physics.
  • #1
palleon
1
0
Hi, I'm new here, and not *really* a physics student, just a guy trying to wrap his head around science by reading lots of books! Stuck on a well known theory, which in my head does not make sense, and hoping someone can clarify...

Homework Statement



A quantum Eraser - this works by adding a vertical polarized lens over one slit of a "2-slit interference pattern creator" and a horizontal polarized lens over the other slit. When added, the interference pattern vanishes and just has one "clump". Replacing with a 50/50 45o lens to both slits, the interference pattern reappears.

The books all tell me this is because you can not measure the effect, and this experience attempts to do that, but by doing so, stops it working. The vertical lens only allows through a vertical particle and so on with the other.

Homework Equations



Surely all this means is that when the photon attempts to "go through both slits at the same time" it is either in a horizontal or vertical state, and so one of the lenses stops that (as it can't be in both states at once). When the 50/50 lens goes on, if the photon can go through one lens it can also go through the other at the same time.

The Attempt at a Solution



This says to me that its not a case of measuring it at all that stops it working, its just you can't put a square peg into a triangular hole.

As the entire book hinges on this "cant measure" rule, so far to me it all appears to be based on a misunderstanding... therefore the whole quantum thing is collapsing for me.

Please, what key part of this am I getting wrong?

Thank you so much.
 
Physics news on Phys.org
  • #2
If the photon did obtain a V or H polarisation by going through either slit, then it takes on a path until the 45/135 degree polariser erases that polarisation. But then getting interference, you'd be changing a definite past.

I think the photon would be best described as a superposition of V and H polarisations after the slit (as would be indicated by QM). Only half of the photons fired towards the slit make it through, and then a subsequent 1/2 of those would make it through the 45 or 135 degree polariser.

The possibility of measuring a V or H polarisation after the photon obtains 45 or 135 degree polarisations is now zero, resulting in the fringe and anti-fringe interference patterns.
 

FAQ: Unraveling the Mystery of Quantum Eraser - Help Needed!

What is the quantum eraser effect?

The quantum eraser effect is a phenomenon in quantum physics where the act of measuring a particle's state can change its behavior, even after the measurement has been made. This concept is based on the principles of superposition and entanglement, which are fundamental to quantum mechanics.

How does the quantum eraser experiment work?

The quantum eraser experiment involves using a beam splitter to send a photon through two paths, creating a superposition of states. One path has a detector that measures the photon's path, while the other path has a detector that measures the photon's polarization. By changing the settings on the second detector, the observer can either "erase" or preserve the information about the photon's path, which affects its behavior.

What is the significance of the quantum eraser effect?

The quantum eraser effect challenges our understanding of causality and the concept of objective reality. It suggests that the act of observation can influence the behavior of particles, even in the past. This has profound implications for our understanding of the nature of reality and the role of consciousness in the universe.

How does the quantum eraser effect relate to the double-slit experiment?

The quantum eraser effect is a variation of the double-slit experiment, where the observer's actions can affect the outcome of the experiment. In the double-slit experiment, the behavior of particles is influenced by whether or not they are being observed. The quantum eraser effect takes this concept further by showing that the observer's actions can also change the behavior of particles after the measurement has been made.

What are the potential applications of the quantum eraser effect?

The quantum eraser effect has potential applications in quantum cryptography and quantum computing. It could also lead to new technologies for secure communication and data storage. Furthermore, it could help us better understand the fundamental principles of quantum mechanics and potentially lead to new discoveries in the field of physics.

Similar threads

Replies
19
Views
1K
Replies
3
Views
2K
Replies
1
Views
851
Replies
1
Views
1K
Replies
1
Views
1K
Replies
5
Views
1K
Back
Top