Curriculum / Entanglement & Protocols / Quantum Teleportation
Quantum Teleportation
Transfer a quantum state using entanglement.
Quantum Teleportation
Quantum teleportation is one of the most counterintuitive results in physics. Using a shared entangled pair and just two classical bits, Alice can transfer the complete quantum state of a qubit to Bob, even though she never learns what the state is, and even though no quantum information travels directly between them.
The word "teleportation" is borrowed from science fiction, but the mechanism is entirely real. It was first demonstrated experimentally in 1997 and has since been achieved over distances exceeding 100 km of optical fiber and via satellite link.
What Gets Teleported (and What Doesn't)
Before the protocol: Alice holds an unknown qubit |ψ⟩ = α|0⟩ + β|1⟩ she wants to give Bob. She does not know α or β, if she did, she could just tell Bob the complex numbers and he could reconstruct the state classically.
After the protocol: Bob's qubit is in state |ψ⟩. Alice's qubit is destroyed, collapsed by her Bell measurement to a definite basis state. The no-cloning theorem is respected: the state moved, it was not duplicated.
Teleportation requires Alice to send Bob two classical bits (her measurement outcomes). Until Bob receives those bits and applies the corresponding corrections, his qubit is in a uniformly random state, it carries zero information about |ψ⟩. Quantum teleportation cannot transmit information faster than light. The entanglement provides the quantum channel; the classical bits provide the correction instructions.
The Three Resources Consumed
Quantum teleportation consumes exactly three resources:
- 1.One shared Bell pair, the entanglement resource, prepared in advance and distributed to Alice and Bob
- 2.Two classical bits, Alice's measurement outcomes, sent to Bob over any classical channel
- 3.Alice's original qubit, destroyed in the process (Alice's Bell measurement collapses it)
Think of the Bell pair as a pre-loaded quantum channel. The two classical bits activate and correct the channel. Without the classical bits, Bob's qubit is useless, this is why teleportation does not allow faster-than-light communication.
This is the opening of the lesson. The full walkthrough, the interactive circuit, and the graded challenge continue inside myqubit.
How this lesson works
A hands-on coding challenge. You write Qiskit-compatible Python in the browser editor, run it instantly via WebAssembly, watch the circuit and Bloch sphere react, and pass automatic output checks. The AI tutor Qubitus gives Socratic hints if you get stuck.
Part of: Entanglement & Protocols
Master multi-qubit systems, quantum teleportation, and cryptographic protocols.
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