Quantum Teleportation

Teleportation transfers an unknown qubit state using a shared entangled pair and two classical bits — no faster-than-light communication, but the backbone of quantum networks.

Resource

1 Bell pair + 2 classical bits

Copies?

no — the original is destroyed (no-cloning)

Use

quantum networking, gate teleportation

What it does

Alice entangles her unknown qubit with her half of a Bell pair via a CNOT and Hadamard, measures both, and sends the two classical outcomes to Bob, who applies X and/or Z corrections to recover the exact state on his half.

Circuit sketch

Where it's used

Quantum repeaters and networks, and 'gate teleportation' — a fault-tolerance technique for applying hard gates like T.

In code (Qiskit)

qc = QuantumCircuit(3,2)
qc.h(1); qc.cx(1,2)   # Bell pair
qc.cx(0,1); qc.h(0); qc.measure([0,1],[0,1])
# Bob: apply X/Z conditioned on classical bits