Teleporting a qubit

This section describes a rudimentary scenario in which the state of a receiver’s qubit becomes identical to the original state of a sender’s qubit. We call this quantum teleportation, or teleportation for short. In our description of teleportation, the phrase original state is important. After all, a qubit can’t be cloned. The sender’s qubit may start in state , but it ends up in state |0⟩ or state |1⟩. In the meantime, the receiver’s qubit goes into state .

Here’s how teleportation works.

A device sits halfway between a sender named Alice and a receiver named Bob. We call this device a repeater, but it’s nothing like the repeaters in our classical networking examples. The device is closer to both the sender and the receiver than they are to each other. In fact, the device can reliably send qubits to both the sender and the receiver. These qubits are entangled with one another, and that makes teleportation...