System and method for key distribution using quantum cryptography

摘要: A method of communication based on quantum cryptography is modified to include an initial step outputting from, e.g., a transmitter (T), single-photon signal, which may be unmodulated. receiver (R1-R3) then randomly selects one plurality encryption alphabets corresponding different, non-commuting mechanical operators. The modulates the signal with selected operator and returns transmitter. in turn uses that detecting returned modulated by receiver. Alternatively, select use alphabet modulating signal. further at using predetermined alphabet. When received back transmitter, it detected same as was initially used modulate it. Comparison made states signals transmitted detect presence any eavesdropper.