Real Time Entanglement from the Zeilinger Group

[Charles Wilson]

"Real Time Entanglement" from the Zeilinger Group



And the "Gee Whiz!" article that referenced it:

http://www.preposterousuniverse.com/blog/2013/05/29/visualizing-entanglement-in-real-time/

CW

 

[DevilsAvocado]

Freaking ey! I almost fell of the chair!

http://arxiv.org/abs/1212.5058

Quantum Entanglement is widely regarded as one of the most prominent features of quantum mechanics and quantum information science. Although, photonic entanglement is routinely studied in many experiments nowadays, its signature has been out of the grasp for real-time imaging. Here we show that modern technology, namely triggered intensified charge coupled device (ICCD) cameras are fast and sensitive enough to image in real-time the effect of the measurement of one photon on its entangled partner. To quantitatively verify the non-classicality of the measurements we determine the detected photon number and error margin from the registered intensity image within a certain region. Additionally, the use of the ICCD camera allows us to demonstrate the high flexibility of the setup in creating any desired spatial-mode entanglement, which suggests as well that visual imaging in quantum optics not only provides a better intuitive understanding of entanglement but will improve applications of quantum science.

https://www.youtube.com/watch?v=wGkx1MUw2TU


Thanks CW!


P.S: Doesn’t the correlations look a bit like ‘electron clouds’...??

 

[DevilsAvocado]

More info:

Quantum entanglement for the first time live on camera [Google translate]

In the new experiments, using a recently developed method pairs of entangled particles of light, called photons produced. One of the particles is selected such that a complex spatial pattern is formed when a large number of photons are absorbed by a highly sensitive camera - assuming that this will be triggered in each case at the right time. As a start signal for real-time recording, the second photon, which is detected in the conventional measuring apparatus is used. The shot with the camera photon has to travel only over 35 meters through a glass fiber before it is "photographed". Once there, the observed pattern, however, depends on exactly what happened with the first particle. "The setting of the measuring equipment for the first particle determines how the pattern looks, which leaves the second particle on the camera, despite the fact that the two instruments are that measure different photons that are clearly separated from each other independently," said Robert Fickler, author of the work. The start signal contains no information about how exactly the first photon was measured, and otherwise the camera does not receive any information about the settings of the other measuring apparatus. But nevertheless, the measured pattern of the camera depends on the previous measurement on the first photon from - exactly how quantum theory predicts it.

http://www.nature.com/srep/2013/130529/srep01914/images_article/srep01914-f1.jpg[/PLAIN] [/QUOTE]

 

[Charles Wilson]

See also:

http://www.nature.com/srep/2013/130529/srep01914/full/srep01914.html

Scroll down to the bottom for some other...ummm...nice pictures.

CW

 

[Ravi Mohan]

That is real treat. It is one thing to study the theory and imagine, and other thing to watch it actually happening. Thank you for sharing this article.

 

[DennisN]

Thanks! What can I say? It's beautiful. But troublesome to me. I might have to change my understanding of entanglement. I've got to read that paper more than once, and I look forward to posts from more PF members about this. I'm feeling slightly dizzy about this thing . But it's beautiful.

 

[DennisN]

See also:

http://www.nature.com/srep/2013/130529/srep01914/full/srep01914.html

Scroll down to the bottom for some other...ummm...nice pictures.

CW

I just want to say there are also two supplementary movies, clip 1 and clip 2, and one supplementary info pdf at the absolute bottom of that page (maybe this is what Charles meant, I'm not sure, nevermind).

 

[Charles Wilson]

I just want to say there are also two supplementary movies, clip 1 and clip 2, and one supplementary info pdf at the absolute bottom of that page (maybe this is what Charles meant, I'm not sure, nevermind).

DennisN: It's all good. Same to DevilsAvocado. I am simply astounded by what people like Zeilinger and his group are doing. I'm enough of a dyslexsh...dyzlecx...dyslƩ≈... can't-see-the-forest-for-the-trees person that I appreciate any listing of new material on this.

CW

 

[DevilsAvocado]

... I’m still stunned ... couldn’t sleep last night ...

Where is the coincidence counting!?

http://arxiv.org/abs/1212.5058]However,[/PLAIN] the biggest advantage of ICCD cameras is the very fast (~2ns) and precise (~10ps) optical gating of the intensifier which makes it possible to use them in a coincidence scheme for real-time imaging of quantum entanglement.

[...]

If no polarizer is put in the path of the trigger photon (bottom right) a statistical mixture of all states of the LG-Bloch sphere is registered. (b) If the delay is changed to a wrong value by 10ns, the gating time of the ICCD camera does not match the arrival of the delayed photons and nearly no intensity is registered. This demonstrates the high signal to noise ratio and the capability of high temporal resolution.

[...]

While visual observation already intuitively confirms the presence of entanglement, we also verify it quantitatively: Since the registered signal of the camera depends linearly on the detected photon number, we determine the average signal per detected photon and its error margin from many single photon events (Supplementary Information). With this relation between registered signal and corresponding photon number it is possible to spatially analyse any recorded intensity image without the need for individual counting of single photons over a time consuming data acquisition of many sparse images.

[my bolding]

Unless I’m totally lost – blockbuster #2 is the real-time coincidence scheme!

But how is it done!? “If no polarizer is put in the path of the trigger photon” must mean that they can tell from the polarization of only the “trigger photon” when the entangled pair is present in the system? If this is correct it’s just amazing...

And what happens if one day we could produce entangled pair in a controlled way, and thus no need for the trigger cable?? (FTL!? :O)

 

[DennisN]

I think I have digested it better now (I hope ).

Polarizer A works like a selection device which ideally transmits 50% of the incoming photons and blocks the remaining 50%.

The arrival of a transmitted photon A triggers the camera (there is only one camera catching photons from stream B).

When polarizer A gets rotated, different selections of photonstream B get caught by the camera.

Remove polarizer A, and all of photonstream B would be caught, showing no signs of entanglement.

I think the setup also is a good demonstration that no real "FTL" information can be transmitted; both streams are needed as input to the camera in order to reveal the entanglement. The ICCD camera is obviously in one and the same location - disconnect/block any of the streams going into it, and: no sign of entanglement.

Anyway, it's a beautiful experiment.

 

[mfb]

No entanglement experiment can give FTL without a violation of quantum mechanics. To transmit information, you always need some non-superluminal signal. This can be a trigger signal, it can be a measurement result, or anything else, depending on the setup. But you need something.

 

[Cthugha]

Where is the coincidence counting!?

It is that long cable between the detecor and the ICCD. The ICCD is triggered. It is only registering data when the other detector tells it to which is equivalent to coincidence counting.

But how is it done!? “If no polarizer is put in the path of the trigger photon” must mean that they can tell from the polarization of only the “trigger photon” when the entangled pair is present in the system? If this is correct it’s just amazing...

Well, the "if no polarizer is present"-part just gives you the picture in the lower right corner. It just gives you a Laguerre-Gaussian mode which does not tell you anything about whether entanglement is present or not. You just know that ta photon has been detected at the other side and the quite short gating time of the ICCD is used to keep the noise at bay.

 

[DevilsAvocado]

So little time and so much to say (including PM:s), I have to come back tomorrow...