Abstract: A quantum key distribution device comprises an input signal path receiving a plurality of optical input signals from a transmitter device, an output signal path connected to the input signal path at a first end and emitting a plurality of first optical output signals at a second end, and a detector signal path connected to the input signal path at a third end and comprising a photon detector device at a fourth end opposite to the third end. The photon detector detects optical input signals from the transmitter device, and the quantum key distribution device establishes a shared quantum cryptographic key with the transmitter device based on the detected optical input signals. The input signal path forms an input path of a Mach-Zehnder interferometer, and the output signal path and the detector signal path form output paths of the Mach-Zehnder interferometer.

Abstract: A system and method for quantum key distribution includes determining an intrinsic loss along a quantum channel; generating a pulse sequence; transmitting the pulse sequence via the quantum channel; receiving the pulse sequence; determining invalid signal positions and providing the invalid signal positions; determining a first reconciled signal from the first signal and the invalid signal positions, and determining a second reconciled signal from the second signal and the invalid signal positions; determining a total loss along the quantum channel from the at least one test pulse received, determining a signal loss from the total loss and the intrinsic loss, and providing the signal loss; determining a shared by error correcting the first reconciled signal and the second reconciled signal; and determining an amplified key from the shared key by shortening the shared key by a shortening amount that is determined from the signal loss.

Abstract: A system and method for quantum key distribution includes determining an intrinsic loss along a quantum channel; generating a pulse sequence; transmitting the pulse sequence via the quantum channel; receiving the pulse sequence; determining invalid signal positions and providing the invalid signal positions; determining a first reconciled signal from the first signal and the invalid signal positions, and determining a second reconciled signal from the second signal and the invalid signal positions; determining a total loss along the quantum channel from the at least one test pulse received, determining a signal loss from the total loss and the intrinsic loss, and providing the signal loss; determining a shared by error correcting the first reconciled signal and the second reconciled signal; and determining an amplified key from the shared key by shortening the shared key by a shortening amount that is determined from the signal loss.