Quantum teleportation is one of the most counterintuitive and practically significant protocols in quantum information science. Unlike science fiction matter transport, it transfers quantum states — quantum information — not physical particles. That capability is precisely what quantum networks and distributed quantum computing require.
## The Protocol
Proposed by Bennett and colleagues in 1993, quantum teleportation uses a pre-shared entangled pair plus a classical communication channel to transfer an unknown quantum state from Alice to Bob:
1. Alice performs a joint measurement (Bell measurement) on the state she wants to send and her half of the entangled pair.
2. She sends the two classical bits of measurement outcome to Bob via a classical channel.
3. Bob applies the corresponding operation to his half of the entangled pair, reconstructing the target state.
The original state at Alice’s location is destroyed by the measurement — no-cloning is preserved. Bob recovers a perfect copy. Because the classical information travels no faster than light, relativity is not violated.
## Experimental Milestones
In 2017, a Chinese team used the Micius satellite to teleport quantum states from a Tibetan ground station to the satellite over distances exceeding 1,400 km — a world record at the time. See the [original Nature paper](https://www.nature.com/articles/nature23675).
Laboratory demonstrations have achieved teleportation fidelities exceeding 99% for photons, trapped ions, and superconducting qubits. Combined with quantum repeaters, teleportation provides a path to long-distance quantum communication that bypasses photon loss in optical fiber.
Quantum teleportation is a foundational building block for the quantum internet: transferring quantum information between quantum computers, sharing entanglement across network nodes, and enabling distributed quantum computation. See [Quantum Internet](https://sunqi.org/quantum-internet-en/) and [Quantum Entanglement](https://sunqi.org/quantum-entanglement-basics-en/).
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