Bell’s Theorem, Entanglement,
Quantum Teleportation and All That
One of the most surprising aspects of quantum
mechanics is that under certain circumstances it does not allow individual
physical systems, even when isolated, to possess properties in their own right.
This feature, first clearly appreciated
by John Bell in 1964, has in the last three decades been tested experimentally
and found (in most people's opinion) to be spectacularly confirmed. More recently it has been realized that it
permits various operations which are classically impossible, such as
"teleportation" and secure-in-principle cryptography. This talk is a
very basic introduction to the subject, which requires only elementary quantum
mechanics.