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Quantum cryptography
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Uses quantum states for secure keys.
Quantum key distribution (BB84) uses photon polarisations; any eavesdropping disturbs the states and is detected. It's secure by physics rather than computation.
Used in satellite links.
Needs authenticated classical channel.
In more detail
Quantum cryptography uses the properties of quantum states to detect eavesdropping. In protocols such as BB84, any measurement by an eavesdropper disturbs the states and reveals their presence.
Real-world uses
- Quantum key distribution is used in some secure communication networks.
- Banks and governments study quantum-safe encryption.
- Banks and governments explore quantum key distribution, which detects eavesdropping through disturbance of quantum states.
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Frequently asked questions
Is quantum cryptography unbreakable?
It is secure against eavesdropping in principle, though practical implementations have limits.
What is BB84?
A quantum key distribution protocol proposed by Bennett and Brassard in 1984.
How does quantum key distribution detect spies?
Measuring a quantum state changes it, so an eavesdropper would leave traces that the legitimate parties can detect.
Related topics in Quantum Mechanics
Interpretations of QM · Quantum computing: qubits · Quantum gates · Quantum teleportation · Lasers · Population inversion