Quantum trick lets one particle send messages two ways at once

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By Anil Ananthaswamy

In the quantum world, particles behave as if they are in two places at once. It turns out this bizarre property allows two people to send each other one bit of information using a single particle – something that is impossible with classical communications.

Say Alice and Bob each want to send the other a piece of information in the form of a 0 or a 1. In classical communications, each has to send the other a particle encoded with that information. So, you need two particles.

Now, Philip …