Quantum Teleportation Explained: What Moves and What Does Not
The name is misleading
Science fiction teleportation moves a person from one place to another. Quantum teleportation moves something much subtler: the exact state of a qubit. The protocol was proposed in 1993 by Charles Bennett, Gilles Brassard, Claude Crepeau, Richard Jozsa, Asher Peres and William Wootters. It is real, it has been demonstrated many times since, and it is a basic building block of quantum networks and some quantum computer designs.
The cast
Alice has a qubit in an unknown state she wants to send. Bob is far away. Beforehand, Alice and Bob share an entangled pair of qubits, one held by each (see entanglement explained). They also have an ordinary channel, like a phone line, for classical bits.
The steps
- Entangle at the sender. Alice performs a joint operation on her unknown qubit and her half of the entangled pair. This uses a CNOT and a Hadamard (see the gate examples).
- Measure. She measures both of her qubits. She gets two classical bits, one of four combinations. Her original qubit's state is now gone, since measurement has destroyed it.
- Send two bits. She sends those two ordinary bits to Bob, by phone, internet or any normal means.
- Fix up. Bob's half of the pair is now in a state related to the original by one of four simple rotations, and the two bits say which. He applies the matching correction, a Pauli gate or a pair of them. His qubit is now exactly the state Alice started with.
What moved, and what did not
| Thing | Moves? | Notes |
|---|---|---|
| The qubit's state | Yes | Re-created exactly on Bob's qubit |
| The physical particle | No | Bob's qubit was already there |
| Matter or energy | No | Nothing is shipped across |
| Information faster than light | No | Bob needs Alice's two bits, which travel normally |
| A copy of the state | No | Alice's original is destroyed |
Why it does not break the rules
Before Bob receives the two bits, his qubit looks like a completely random mix, whatever Alice's state was. He cannot learn anything from it. Only after the bits arrive, at no more than light speed, can he fix it. So there is no faster-than-light signaling. And because Alice's original is destroyed, the no-cloning theorem is respected: there is one copy of the state before and one after.
Notice that Alice never needs to know the state she is sending. She does not measure it to find out. That is the real trick, because learning an unknown state from a single copy is impossible.
It has been done
The first laboratory demonstrations came in 1997 and 1998. A group at the University of Innsbruck led by Anton Zeilinger published teleportation of photon polarization in Nature in 1997. Later experiments have extended the distance, including over fiber, over free space, and in 2017 from the ground to the Micius satellite, reported by a Chinese team (see China's Micius program).
What it is used for
- Quantum networks and repeaters. Teleportation passes qubits across links where sending a fragile photon through a long fiber would lose it.
- Gates inside computers. Some designs use teleportation to carry out certain gates, including in schemes for fault tolerance, see error correction.
- Linking machines. Ideas for distributed quantum computing rely on moving states between modules.
Common misunderstandings
- "It lets you send messages instantly." It does not. The classical bits are required and travel at normal speeds.
- "It transports people or objects." No matter is transferred. Only a state is re-created, on a qubit.
- "It makes a copy." The original is destroyed, so the total number of copies stays at one.
- "Entanglement alone carries the message." The entangled pair is a resource. Without the two classical bits, Bob's qubit is useless noise.
Sources and further reading
- Bennett et al., Teleporting an unknown quantum state, Physical Review Letters 70 (1993)
- Bouwmeester et al., Experimental quantum teleportation, Nature 390 (1997)
- IBM Quantum Learning (successor to the Qiskit textbook)
Standard textbook physics, reported as of 2026-10-09. Nothing here is financial advice. The QNT memecoin is independent of Quantinuum Ltd, the real company, and of every lab, university and prize body named on this page.
Frequently asked questions
Does quantum teleportation travel faster than light?
No. Bob must wait for two classical bits from Alice, and those cannot travel faster than light.
What is destroyed in teleportation?
Alice's original state is destroyed when she measures it, which is why teleportation does not violate the no-cloning theorem.
How many classical bits are needed per qubit?
Two bits for each teleported qubit, telling Bob which of four corrections to apply.
Who first demonstrated it?
The protocol was proposed in 1993. First lab demonstrations with photons came in 1997 and 1998, including a Nature paper from the Zeilinger group in Innsbruck.
Keep reading
- Quantum Entanglement Explained Simply
Entanglement links qubits so they share a joint state. Learn what it is, what it is not, and why quantum computers use it. - The No-Cloning Theorem Explained: Why You Cannot Copy a Qubit
The no-cloning theorem says an unknown quantum state cannot be copied. Here is the intuition, why it protects quantum cryptography, and why it complicates error correction. - Distributed Quantum Computing: Wiring Quantum Computers Together
How teleporting gates between separate modules could scale quantum computers, with the 2025 Oxford result and Cisco's networking plans. - Bell Inequalities Explained: What Experiments Showed and the 2022 Nobel
Bell inequalities test whether hidden local variables could explain quantum results. Experiments say no. The 2022 Nobel Prize went to Aspect, Clauser and Zeilinger.
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