Mach-Zehnder interferometer, but with an entangled beam?

[DrChinese]

1/ It seems that a beam of entangled particles carries a message ! This message is "I am entangled".
In other words, trying to create interference by all means without success, with a beam of which we don't know the source would be the signature of an entangled beam, right ?

Although the PDC source is a laser, the entangled beam that comes from the crystal lacks one attribute that is typical of laser light: coherence. Coherence is needed for the interference to appear. You *can* make the light be coherent, but then it will lose some of its entangled properties. To the extent you get more of one attribute, you get less of the other.

 

[Marilyn67]

Hello @DrChinese ,

Thank you for your quick response.

Something escapes me:

In 1803, Thomas Young performed his experiment of the two slits with a beam of sunlight and found interference.
A reproduction of the experiment can be seen here as well as the reading of Thomas Young's manuscripts :



I thought sunlight wasn't coherent light, like from an incandescent bulb ?

Cordially,
Marilyn

 

[DrClaude]

I thought sunlight wasn't coherent light, like from an incandescent bulb ?

There is a nice discussion of this at StackExchange: https://physics.stackexchange.com/q...interference-in-youngs-double-slit-experiment

 

[Marilyn67]

Thank you @DrClaude, this discussion is indeed very interesting !