A field using quantum mechanics for secure information transfer.Quantum communication is a field that leverages the principles of quantum mechanics to transmit information in a way that is fundamentally secure. Unlike classical communication, where information is encoded in bits that can be copied or intercepted without detection, quantum communication uses quantum states, such as the polarization of a photon, to encode information. A key feature is that any attempt to measure or eavesdrop on a quantum channel inevitably disturbs the state, alerting the sender and receiver to the presence of an intruder.
The concept was first proposed by Stephen Wiesner in the 1970s, and the first practical QKD protocol (BB84) was developed by Charles Bennett and Gilles Brassard in 1984.
The most common protocol is quantum key distribution (QKD), where a sender (Alice) sends a sequence of photons in random quantum states to a receiver (Bob). They then compare a subset of their measurements over a classical channel to detect any eavesdropping. If no eavesdropping is detected, they can use the remaining measurements to generate a shared secret key, which can be used for encryption. The security relies on the no-cloning theorem, which states that an unknown quantum state cannot be perfectly copied.
Quantum communication is used in secure communication networks, such as those for government and financial institutions, and is a key component of future quantum internet.
Quantum key distribution has been demonstrated over distances exceeding 1,000 kilometers using satellite-based links.
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