I importance of Hanbury Brown and Twiss experiment

[qnach]

I read Hanbury Brown and Twiss's experiment is using one beam but split into two to test their correlation.
It said the traditional correlation test were using two beams........
This confused me, sorry.

All the correlation tests I learnt such as Stern-Gerlash are using one beam? (Sorry if I am wrong)
I was also told traditional interferometers are concerning about amplitude but Hanbury Brown and Twiss were concerning about intensity?
Isn't the square of amplitude is the intensity?

Please advice me where did I made mistake?

 

[PeterDonis]

Stern-Gerlash

A single Stern-Gerlach experiment is not a "correlation experiment". To do a correlation experiment with Stern-Gerlach devices, you need two such devices, each of which measures one of two entangled particles. Just as in the Hanbury-Brown-Twiss effect, you need two detectors, not one.

 

[PeterDonis]

I read Hanbury Brown and Twiss's experiment is using one beam but split into two to test their correlation.

I was also told traditional interferometers are concerning about amplitude but Hanbury Brown and Twiss were concerning about intensity?

It would help if you would give specific references for where you read or were told these things.

 

[PeterDonis]

using one beam but split into two to test their correlation

Yes. You have one light beam coming from a source, which is split by a beam splitter, and then you have two detectors, and you look for correlations between the detections. The correlations give you information about the light source.

 

[qnach]

This is the Michelson-Morley interferometery I know of. Is it one source or two sources?

 

[qnach]

This is the Mach-Zender interferometer I know of. Is it one source or two sources?

 

[realJohn]

The difference is that traditional interferometers focus on amplitude and phase using separate beams or paths, while Hanbury Brown and Twiss split one beam and look at intensity correlations between two detectors. Since intensity is the square of amplitude, HBT is really about how the intensity fluctuates over time, which reveals effects like photon bunching. So it’s less about the wave itself and more about the statistics of the light, which is why it’s different from things like Stern-Gerlach or regular interferometry.

 

[qnach]

It would help if you would give specific references for where you read or were told these things.

OK. Here is an example that saying HBT measures intensity
https://physicstoday.aip.org/news/glauber-hall-and-hansch-share-the-2005-nobel-prize-in-physics
on page 19 (the first page of that article) upper-right corner.....
the Hanbury Brown–Twiss (HBT) apparatus measured the correlation in the intensities ....

 

[WernerQH]

Have a look at https://en.wikipedia.org/wiki/Hanbury_Brown_and_Twiss_effect

The effect seemed puzzling at the time, because of Dirac's remark that "a photon only interferes with itself" in his textbook. But E.Purcell showed that the HBT effect can also be understood classically:
E. Purcell (1956). "The Question of Correlation Between Photons in Coherent Light Rays". Nature. 178 (4548): 1449–1450.
(from the Wikipedia page)

 

[realJohn]

https://physicstoday.aip.org/news/glauber-hall-and-hansch-share-the-2005-nobel-prize-in-physics

This clearly illustrates how the HBT apparatus measures intensity correlations, distinguishing it from traditional interferometry that focuses on amplitude and phase. This approach provides insights into the statistical properties of light, such as photon bunching, which are crucial for understanding quantum phenomena.

 

[qnach]

A single Stern-Gerlach experiment is not a "correlation experiment". To do a correlation experiment with Stern-Gerlach devices, you need two such devices, each of which measures one of two entangled particles. Just as in the Hanbury-Brown-Twiss effect, you need two detectors, not one.

OK Stern-Glash is not (Sorry I am very confused). It is not even an interferometry. But how about Michelson-Morley and Mach-Zehnder?

 

[qnach]

This clearly illustrates how the HBT apparatus measures intensity correlations, distinguishing it from traditional interferometry that focuses on amplitude and phase. This approach provides insights into the statistical properties of light, such as photon bunching, which are crucial for understanding quantum phenomena.

Which one clearly illustrates? Sorry please explain...I am confused...

 

[qnach]

Have a look at https://en.wikipedia.org/wiki/Hanbury_Brown_and_Twiss_effect

The effect seemed puzzling at the time, because of Dirac's remark that "a photon only interferes with itself" in his textbook. But E.Purcell showed that the HBT effect can also be understood classically:
E. Purcell (1956). "The Question of Correlation Between Photons in Coherent Light Rays". Nature. 178 (4548): 1449–1450.
(from the Wikipedia page)

I tried to obtain this paper https://www.nature.com/articles/1781449a0
But why has it no title as you said "The Question of Correlation Between Photons in Coherent Light Rays"

 

[WernerQH]

I tried to obtain this paper https://www.nature.com/articles/1781449a0
But why has it no title as you said "The Question of Correlation Between Photons in Coherent Light Rays"

I just copied the wikipedia reference, and it seems to point to a nature paper with that title. Unfortunately it's behind a paywall. Have your read the wikipedia page?

 

[realJohn]

Which one clearly illustrates? Sorry please explain...I am confused...

The article explains how the Hanbury Brown and Twiss (HBT) experiment utilizes intensity correlations between two detectors to analyze light's statistical properties. This method contrasts with traditional interferometry, which focuses on amplitude and phase correlations. By measuring intensity correlations, the HBT experiment provides insights into phenomena like photon bunching, which are essential for understanding quantum optics.