Final answer:
Quantum Key Distribution exploits quantum mechanics for secure communication, leveraging quantum properties like the disturbance upon measurement to prevent eavesdropping. Protocols like BB84 use quantum states to generate a shared key, which is disturbed if intercepted, thus revealing any tampering.
Step-by-step explanation:
Quantum Key Distribution (QKD) exploits the principles of quantum mechanics to achieve secure communication. It uses quantum properties of particles, such as photons, to create a shared key between two parties that can subsequently be used to encrypt and decrypt messages. The security of QKD stems from the fundamental quantum phenomenon that any measurement of a quantum system inevitably disturbs it. Therefore, an eavesdropper trying to intercept the key will introduce detectable anomalies in the communication, alerting the users to the presence of an intrusion.
One of the most well-known protocols in QKD is the BB84 protocol, developed by Charles Bennett and Gilles Brassard in 1984. In this scheme, several quantum states are prepared by the sender (commonly referred to as Alice), which are then transmitted to the receiver (Bob). Because of the quantum properties of the transmitted particles, any attempt by an eavesdropper (Eve) to measure these quantum states will alter them, which can be detected by Bob during the key reconciliation process.