Quantum Teleportation

Physics: Quantum teleportation (Bennett et al. 1993): transmit unknown state |ψ⟩ using EPR pair + 2 classical bits. Protocol: Alice has |ψ⟩ ⊗ (|00⟩+|11⟩)/√2; measures qubits 1,2 in Bell basis (4 outcomes: Φ±, Ψ±); sends 2 classical bits to Bob; Bob applies correction (I, X, Z, or XZ) to recover |ψ⟩ exactly. No-cloning theorem: original |ψ⟩ is destroyed. No FTL: classical channel is required for correction. Experimentally: Bouwmeester 1997, Pan 1997 (photons); Riebe 2004 (ions); Ren et al. 2017 (1400 km via Micius satellite). Building block for quantum internet and distributed quantum computing.