LMU physicists have, for the first time, successfully
transmitted a secure quantum code through the atmosphere from an aircraft to a
ground station.
Can worldwide communication ever be fully secure? Quantum
physicists believe they can provide secret keys using quantum cryptography via
satellite. Unlike communication based on classical bits, quantum cryptography
employs the quantum states of single light quanta (photons) for the exchange of
data. Heisenberg’s uncertainty principle limits the precision with which the
position and momentum of a quantum particle can be determined simultaneously,
but can also be exploited for secure information transfer. Like its classical
counterpart, quantum cryptography requires a shared key with which the parties
encode and decode messages. However, quantum mechanical phenomena guarantee the
security of quantum key distribution. Because quantum states are fragile,
interception of the key by an eavesdropper will alter the behavior properties
of the particles, and thus becomes detectable.