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Information about this web site => Request for physics Simulations => Topic started by: StevieT on July 09, 2011, 02:12:36 pm



Title: Scully's Quantum Eraser Experiment
Post by: StevieT on July 09, 2011, 02:12:36 pm
Hi there!

Tried to find a similiar application but no luck thus far.

I'm hoping for an application that allows me to simulate Scully's delayed choice quantum eraser experiment. Perferably with the source emitting a particle, and me being able to erase 'information' AND find out which-way (by opening a shutter) [so perhaps two screens with particle marking in the same spot] - but each screen colour coded differently to whether I did erasing (on screen 1) or find out which way info (on screen 2). Then repeating the process again (keeping the previous markings there).


Title: Re: Scully's Quantum Eraser Experiment
Post by: Fu-Kwun Hwang on July 09, 2011, 08:38:13 pm
Could you explain it in more detail? It will be even better if a simple drawing is provided.


Title: Re: Scully's Quantum Eraser Experiment
Post by: islids on July 12, 2011, 09:59:34 am
Good


Title: Re: Scully's Quantum Eraser Experiment
Post by: StevieT on July 13, 2011, 10:08:55 am
Could you explain it in more detail? It will be even better if a simple drawing is provided.

Hi!

Here is an image for the experimental set-up, with additional information.
http://img.photobucket.com/albums/v608/steviet/scan0002.jpg

Cheers!
Stevie


Title: Re: Scully's Quantum Eraser Experiment
Post by: Fu-Kwun Hwang on July 13, 2011, 02:38:05 pm
You can attached image when you post forum message.
(http://www.phy.ntnu.edu.tw/ntnujava/index.php?action=dlattach;topic=2231.0;attach=4286;image)

1. Do you mean there is a continue beam of atom moving toward a screen with two slits?
2. Does atom move with the same speed v (or random speed),separated by the same distance(or randomly)?
3. What do you mean by "detector click or not"??? How to decide?
4. What kind of information need to be recorded/shown? 

All the information need to be provided in order to create a simulation!


Title: Re: Scully's Quantum Eraser Experiment
Post by: StevieT on July 22, 2011, 06:27:37 am
1. Do you mean there is a continue beam of atom moving toward a screen with two slits?
One excited atom at a time being sent towards the screen.[/quote]

2. Does atom move with the same speed v (or random speed),separated by the same distance(or randomly)?
Each excited atom moves at the same speed. The distance between the source and screen stays the same each time.

3. What do you mean by "detector click or not"??? How to decide?
When only one shutter is opened, either the detector will click or not (randomly, of course obeying QM statistics). So 50% of the time a photon will be found in the top cavity; 50% of the time a photon will be found in the bottom cavity. Say we open the top shutter, and the atom had passed through the top slit, then the detector will click because a photon would be in the top cavity. If, say we had opened the bottom shutter instead, the detector won't click, which would tell us the atom took the top path and there is a photon in the top cavity.

When erasure occurs, i.e. when we open both shutters at the same time 50% of the time we get a click, and 50% of the time we don't get a click (each event occurs randomly), which is in accord with Quantum Mechanics predictions.

BOTH one shutter being opened, and both shutters being opened at the same time, will be done, for each atom that hits the final screen. Of course whether we get a click or not is random each time, but in accordance with the predictions of Quantum Theory.

4. What kind of information need to be recorded/shown?
Record where each atom hits the screen. Take two copies of that screen now, and then for copied screen 1 we'll find out which slit the atom went through, and mark the point on the screen in accordance with the key in the image I posted in a previous post. For copied screen 2, we'll erase the information, and mark the point on the screen again in accordance with the key I provided.

Each time a new atom hits the screen, leave the previous marking on the copied screen (with its coloured key point as per eraser or which-slit info) and repeat the steps done to colour the previous marking, for the new marking.


So in effect, each time we send an atom to the screen, we are doing two different experiments for the same atom, at seperate times. Each time we send an atom to the screen, we are finding out which slit it went through, and then another experiment to plot what the final screen pattern would look like HAD we done erasure instead of finding out which slit info.

Question: Will the simulation, when built, reproduce the predictions of Quantum Mechanics?

This image might help: it is the original discussion of the though experiment itself which we're going to republicate. Not sure if you've seen it before or know about it.

(http://img.photobucket.com/albums/v608/steviet/Delayed-ChoiceQuantumEraserExperiment.jpg)


Title: Re: Scully's Quantum Eraser Experiment
Post by: Fu-Kwun Hwang on July 22, 2011, 07:46:43 am
I can not image there is a spatial distribution of photon on the screen from the experimental you described:

There are two slits: A and B. Photon could select  to pass either slit A or slit B.
The number being recorded are (Possible results are)
1. photon pass slit A and detector A find it.
2. photon pass slit A and detector A did find it.
3. photon pass slit B and detector B find it.
4. photon pass slit B and detector B did find it.
 
I can not find the connection between what you have described and results shown in the attached picture.


Title: Re: Scully's Quantum Eraser Experiment
Post by: StevieT on July 22, 2011, 01:16:11 pm
I can not image there is a spatial distribution of photon on the screen from the experimental you described:

There are two slits: A and B. Photon could select  to pass either slit A or slit B.
The number being recorded are (Possible results are)
1. photon pass slit A and detector A find it.
2. photon pass slit A and detector A did find it.
3. photon pass slit B and detector B find it.
4. photon pass slit B and detector B did find it.
 
I can not find the connection between what you have described and results shown in the attached picture.

There has always only been one detector, located between the shutters.

When you say "2. photon pass slit A and detector A did find it." do you actually mean "2. photon pass slit A and detector A didn't find it. This is completely equivalent to the point on the screen being yellow when shutter two is opened, and the detector never found it, indicating the atom went passed through slit A (the top slit), and not slit B (the bottom slit).

What is different between what the scan says, and what I've drawn on my image, is that for when what I've just described occurs (non-detection of a photon when one shutter is opened), we are colour coding those, instead of the usual X to indicate whether it goes through slit A (by detecting it from the top cavity, or not detecting it in the bottom cavity), and vice versa for the O.

When you do erasure of information - when both slits are opened the detector can click (to indicate constructive interference: remember, the photon does not exist in either cavity until you find it there, so when you open both shutters, you are getting wave interference from the possibility of the photon being in either cavity), or no click, which would indicate destructive interference -- each with 50% probability occuring. 50% of the time constructive interference occurs, 50% of the time destructive interference occurs. [see 4--> of the image]

Hope I've clarified things a bit further. :)


Title: Re: Scully's Quantum Eraser Experiment
Post by: Fu-Kwun Hwang on July 22, 2011, 11:52:00 pm
Are you thinking about something like the following youtube movie?
[youtube=htSIjIyF9bU]


Title: Re: Scully's Quantum Eraser Experiment
Post by: StevieT on July 23, 2011, 10:27:36 am
Yup, but with the experimental set-up of Scully, Englert and Walther.

http://www.nature.com/nature/journal/v351/n6322/abs/351111a0.html


Title: Re: Scully's Quantum Eraser Experiment
Post by: Fu-Kwun Hwang on July 26, 2011, 11:29:12 am
I can not find the article from the above URL. (Only limited abstract and reference available).

Could you provide more information?


Title: Re: Scully's Quantum Eraser Experiment
Post by: Pearlype on July 29, 2011, 03:43:48 am
Hi there!

Tried to find a similiar application but no luck thus far.

I'm hoping for an application that allows me to simulate Scully's delayed choice quantum eraser experiment. Perferably with the source emitting a particle, and me being able to erase 'information' AND find out which-way (by opening a shutter) [so perhaps two screens with particle marking in the same spot] - but each screen colour coded differently to whether I did erasing (on screen 1) or find out which way info (on screen 2). Then repeating the process again (keeping the previous markings there).

You make a number of valid items in your article and would likely believe many.Thank you very much this is a very nice information!. . .I use this information my practical life.

Pearlype