Ghost Imaging - FLT, what is missing here?

[San K]

In ghost imaging the idler photons can be used to get an idea of an object (say shape) in the path of the signal photons.

Is not the information of the shape of the object (in the path of the s-photon) being transmitted to p-photons (idlers) faster than light? (via entanglement)

What am I missing here? Is my understanding of Ghost imaging correct/complete?

http://www.newscientist.com/article/dn13825

 

[San K]

In ghost imaging the idler photons can be used to get an idea of an object (say shape) in the path of the signal photons.

Is not the information of the shape of the object (in the path of the s-photon) being transmitted to p-photons (idlers) faster than light? (via entanglement)

What am I missing here? Is my understanding of Ghost imaging correct/complete?

i think i found the answer:

To get the ghost image the s and p- photons need to be paired via a co-incidence counter.

Is the above reasoning correct?

 

[Hia Hasmut]

Can you provide a link regarding this Imaging technique

 

[my_wan]

Yes, though ghost imaging is based on second-order correlation functions.

Direct and ghost interference in double-slit experiments with coincidence measurements
http://arxiv.org/abs/0812.2633

A Novel Algorithm for Ghost Imaging with a Single Detector
http://lanl.arxiv.org/abs/1101.4869

 

[San K]

Can you provide a link regarding this Imaging technique

i have update the link in the original post, pasted below as well


http://www.newscientist.com/article/dn13825

 

[San K]

Yes, though ghost imaging is based on second-order correlation functions.

Direct and ghost interference in double-slit experiments with coincidence measurements
http://arxiv.org/abs/0812.2633

A Novel Algorithm for Ghost Imaging with a Single Detector
http://lanl.arxiv.org/abs/1101.4869

The second link...i.e. with single detector, shows that quantum entanglement is not required.

then why (do scientists/papers/experiments) use quantum entanglement and Co-incidence counter etc?

 

[my_wan]

The second link...i.e. with single detector, shows that quantum entanglement is not required.

then why (do scientists/papers/experiments) use quantum entanglement and Co-incidence counter etc?

That is what some claim and other differ.
http://lanl.arxiv.org/abs/quant-ph/0608073

You will not always get good agreement on what constitutes and an "entanglement" either. For some it is the result of the coincidence count, for others it is the cause of the coincidence count. Remember the old warning: Correlation does not equal causation (even though causation always causes correlations). Coincidence count measure both, and the debate continues.

 

[Cthugha]

The second link...i.e. with single detector, shows that quantum entanglement is not required.

then why (do scientists/papers/experiments) use quantum entanglement and Co-incidence counter etc?

Well, they do not really use just a single detector. They just use less info from the second detector than most other groups do. However, you are right that entanglement is not required. Ghost imaging works well with thermal light (but not with laser light) because the photon number noise in thermal light is also correlated (the second-order photon number autocorrelation function is not unity). This small amount of correlation is enough to perform ghost imaging.

 

[San K]

Well, they do not really use just a single detector. They just use less info from the second detector than most other groups do. However, you are right that entanglement is not required. Ghost imaging works well with thermal light (but not with laser light) because the photon number noise in thermal light is also correlated (the second-order photon number autocorrelation function is not unity). This small amount of correlation is enough to perform ghost imaging.

thanks for the info