Reproducing Quantum Experiments

[Dennis Plews]

The Nature (Sept 4, 2009), (Science News, Oct. 24, 2009) article on the violation of Bell’s Inequality in Josephson phase quibits exquisitely demonstrated by Dr. John Martinis with his Martinis Group at UC Santa Barbara and Dr. Chris Monroe’s “Schrödinger’s Cat” demonstration with a Be+ ion (Science, Vol. 272, p. 1101, 24 May 1996) done at NIST, Boulder, are fascinating. I am interested in repeating those experiments. Can anyone offer suggestion as to who may be able to reproduce either or both? Thanks.

Dennis Plews
[Personal info removed by moderator]

 

[jambaugh]

You can violate Bell's inequality with simple polarization experiments. The trick is to do so while, at the same time verifying one is carrying out discrete quantum experiments and, typically, also by separating the two half measurements spatially so as to eliminate local causal interactions between them. I would say the other tricky part will be generating the entangled pairs. The first example I recall ever seeing was done via entangled photon pairs traveling along fiber-optic cables. (In Paris? back in the early to mid 90's). The pair production was done with a non-linear crystal hetrodyning a higher energy photon into a lower energy entangled pair. The experiment didn't actually produce a "photon gun" but did lower the emission rate so that numerically there were typically no more than 0.1 photon on average in the device at anyone time.

Finally I would guess the last obstacle is to get your detection reliability up high enough that attenuation does not eat away at the violation margin in the inequality.

If you're only interested in the inequality violation, without the spatial separation business then I'd guess you could set up a simple bench-top experiment relatively easily.

 

[Dennis Plews]

Thank you for your reply. I believe it was Alain Aspect at CERN who did an early experiment confirming it. Re the entangled quibit circuits, I’m interested in seeing how stable and robust the entangled state of the device can be.

 

[f95toli]

There are many, many groups working in this area and by now there must be hundreds of papers describing versions/extensions of the experiments you refer to.
Cat states are routinely created in a variety of systems and Bell test using superconducting qubits are quite common (superconducting qubits was e.g. one of the systems used for the recent "Big Bell test" experiment)

Here is a link to a paper where they describe an experiment which combined both

"Characterizing entanglement of an artificial atom and a cavity cat state with Bell's inequality."
https://www.nature.com/articles/ncomms9970

 

[Dennis Plews]

Thanks again! Do you know what group might be interested in doing a private experiment using such entangled devices?

 

[f95toli]

What does a "private" experiment mean?
Experiments of this type takes months to plan, carry out and analyse and typically requires a lot of very expensive equipment; it is not something you can just do in a few hours.

 

[PeterDonis]

I believe it was Alain Aspect at CERN who did an early experiment confirming it.

Aspect wasn't the first to experimentally test the Bell inequalities (the earliest I can find is Freedman & Clauser, 1972), but his 1982 experiment was the first to make the choice of which measurement to do on each side after the photons were in flight.

 

[PeterDonis]

A good list of Bell test experiments is here:

https://en.wikipedia.org/wiki/Bell_test_experiments#Notable_experiments

 

[Dennis Plews]

What does a "private" experiment mean?
Experiments of this type takes months to plan, carry out and analyse and typically requires a lot of very expensive equipment; it is not something you can just do in a few hours.

I am somewhat familiar with what you say. Chris Monroe told me not long after the Science article about his Be+ superposition demonstration that his set up for it cost about $2M.

 

[Dennis Plews]

Private here means I pay for it and own the rights to the results

 

[mfb]

Why would you pay some 5- to 7-digit amount of your private money to reproduce an experiment? And what does "own the rights to the results" mean? If you don't publish the result it is useless. And you'll have a hard time getting anywhere near the experimental sensitivity the world's leading experts in the field get.

 

[Dennis Plews]

Therein lies a great secret

 

[DrChinese]

Therein lies a great secret

I doubt it. The results will be in line with the predictions of QM. Not exactly a state secret, considering the thousands of Bell tests that have been performed to date.

I paraphase: How do you make a small fortune in entanglement research? Start with a large fortune...

 

[Dennis Plews]

Only time will tell.

 

[vanhees71]

I doubt it. The results will be in line with the predictions of QM. Not exactly a state secret, considering the thousands of Bell tests that have been performed to date.

I paraphase: How do you make a small fortune in entanglement research? Start with a large fortune...

Hm, maybe Zeilinger at all will make some fortune with their application of their fundamental research by commercial realizations of quantum cryptography ;-)).