Quantum Entanglement: Bell's Telephone - Possible FTL Comms?

[maaku]

Faster than light communication w/ Quantum Entanglement (Bell's telephone)--Possible?

I got intrigued by the following description: of a faster than light communications grid over interstellar distances:

http://www.seti.org.au/spacecom/quantumcom.html

Normally I'd ignore such things on the Internet, but this is hosted on a SETI webserver, an institution with generally respectable scientific credentials.

The short summary is that it's Bell's telephone, but with generator of entangled photons moved to half way between the sender and the receiver. Instead of overlaying another signal on top of the light beam (as in Bell's telephone), the sender uses a shutter to alternate blocking the light (say, a 1 bit) vs. just letting it be (a 0 bit). Observation of the resulting interference pattern at the receiving end should (according to the author) allow the receiver to deduce whether or not the shutter was closed at the other end.

Is this true? Despite being a former engineering physics major, my knowledge of quantum entanglement is too rusty to help me out here..

 

[f95toli]

No, even without looking at the reference I can say that this is not correct.
You can't use entanglement to transfer information FTL.

 

[DrChinese]

I got intrigued by the following description: of a faster than light communications grid over interstellar distances:

http://www.seti.org.au/spacecom/quantumcom.html

Normally I'd ignore such things on the Internet, but this is hosted on a SETI webserver, an institution with generally respectable scientific credentials.

The short summary is that it's Bell's telephone, but with generator of entangled photons moved to half way between the sender and the receiver. Instead of overlaying another signal on top of the light beam (as in Bell's telephone), the sender uses a shutter to alternate blocking the light (say, a 1 bit) vs. just letting it be (a 0 bit). Observation of the resulting interference pattern at the receiving end should (according to the author) allow the receiver to deduce whether or not the shutter was closed at the other end.

Is this true? Despite being a former engineering physics major, my knowledge of quantum entanglement is too rusty to help me out here..

Welcome to PhysicsForums, maaku!

No it is incorrect, though this is a good try and many have fallen victim to it. (Me included.) The reason is quite simple: entangled photons generally do not interfere in a double slit apparatus!

Experiment and the foundations of quantum physics

See figure 2, page 290.

 

[DrChinese]

I got intrigued by the following description: of a faster than light communications grid over interstellar distances:

http://www.seti.org.au/spacecom/quantumcom.html

Normally I'd ignore such things on the Internet, but this is hosted on a SETI webserver, an institution with generally respectable scientific credentials.

The author is John Walsh, and it appeared in 1999. That is the same year as the reference I gave above was published. Walsh references Zeilinger (the author of the reference I gave) and obviously was not aware of the little kink I mentioned.

This should definitely be removed from the SETI site, they probably forgot about it years ago.

 

[DrChinese]

I sent a message to someone at SETI. By the way, this looks to be the Australian site. The world is upside down in that place, so maybe quantum mechanics works differently there.

 

[maaku]

Thanks Dr.Chinese! That confirms my intuition, but I had no way of proving it. I look forward to reading the reference you linked to. I appreciate the help!