Quantum Teleportation
Also known as: teleportation, entanglement-assisted communication
Quantum Teleportation is a protocol for transferring an unknown quantum state between distant parties using entanglement and classical communication. Discovered by Bennett et al. in 1993, teleportation violates no fundamental principles but demonstrates the power of entanglement: an unknown quantum state can be reconstructed at a distant location without ever being transmitted.
Key highlights
- Transfers quantum state with certainty (100% fidelity in ideal case).
- Does not violate no-cloning theorem; original state is destroyed by measurement.
- Enables quantum networks without transmitting quantum signals over long distances.
- Experimentally demonstrated over hundreds of kilometers.
- Essential for quantum repeaters and distributed quantum computing.
Intuition
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How it works
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When to use it
Teleportation is used in quantum repeaters for long-distance quantum communication, in quantum networks, and as a building block for quantum algorithms. It requires reliable entanglement distribution and fast classical communication.
Strengths & limitations
- Transfers quantum state with certainty (100% fidelity in ideal case).
- Does not violate no-cloning theorem; original state is destroyed by measurement.
- Enables quantum networks without transmitting quantum signals over long distances.
- Experimentally demonstrated over hundreds of kilometers.
- Essential for quantum repeaters and distributed quantum computing.
- Requires pre-shared entanglement; cost of entanglement distribution.
- Cannot exceed speed of light; still requires classical communication.
- Measurement introduces statistical noise; outcomes random.
- Practical implementations suffer from losses and noise.
- Not useful for single-shot communication of unknown states (classically, you need 2 bits anyway).
Common pitfalls
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Applications
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Frequently asked
Why doesn't teleportation violate relativity?
Teleportation requires classical communication (2 bits) from Alice to Bob. This cannot exceed light speed. No instantaneous transfer occurs; the classical bits must travel at the speed of light.
What is a Bell pair and how is it created?
A Bell pair is a two-qubit entangled state like |Φ+⟩ = (|00⟩+|11⟩)/√2. It can be created using CNOT and Hadamard gates, or through spontaneous parametric down-conversion in optics.
Why must the original state be destroyed?
Alice's Bell measurement collapses her qubit and her half of the entangled pair. This destroys the original state. By no-cloning theorem, perfect copying is impossible; the state cannot exist in two places.
Can teleportation be used for superluminal communication?
No. Alice's measurement outcomes are random. Bob's correction works only after he receives the classical bits. No information is transmitted faster than light.
What is quantum state swapping and how does it relate to teleportation?
Quantum state swapping is exchanging states between two qubits using two consecutive teleportations. It is useful for moving quantum information in quantum networks without measuring final states.
Sources
- 1.Bennett, C. H., Brassard, G., Crépeau, C., Jozsa, R., Peres, A., Wootters, W. K. (1993). Teleporting an unknown quantum state via dual classical and Einstein-Podolsky-Rosen channels. Physical Review Letters, 70, 1895–1899.
- 2.Bouwmeester, D., et al. (1997). Experimental quantum teleportation. Nature, 390, 575–579.
- 3.Ma, X. S., et al. (2012). Quantum teleportation over 143 kilometres using active feed-forward. Nature, 489, 269–273.
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Cite this page
ScholarGate. (2026, June 3). Quantum Teleportation. ScholarGate. https://scholargate.app/quantum-computing/quantum-teleportation