Apparatus and method for decoy-state three-state quantum key distribution

Abstract

The invention relates to a Quantum Key Distribution system comprising a transmitter 300 and a receiver 400 for exchanging a quantum key via a quantum channel 600 through a decoy-state three state protocol wherein the transmitter comprises a transmitter processing unit 340 adapted to use random numbers from a quantum random generator to select a quantum state to encode from different states of intensity and basis, a pulsed light source 310 adapted to generate an optical pulse, a time-bin interferometer 320 through which the generated optical pulse passes and which transforms generated optical pulse into two coherent pulses separated by the time bin duration, a single intensity modulator 360 adapted to change the intensity of the two pulses individually according to the choice made by the transmitter processing unit 340, and a variable optical attenuator 370 adapted to reduce the overall signal intensity to the optimum photon number per pulse.

Description

technical field [0001] The present invention relates to quantum cryptographic protocols and implementations based on quantum key distribution (QKD). Background technique [0002] Quantum cryptography or quantum key distribution (QKD) is a method that allows 10 secret keys to be distributed between two remote parties (sender and receiver) with provably absolute security. [0003] QKD is a secure method that relies on the principles of quantum physics and encodes information in quantum states, or qubits, without the bits used in classical communication. Typically, photons are used for these quantum states. Quantum key distribution exploits certain properties of these quantum states to ensure quantum key distribution security. [0004] More specifically, the security of the method comes from the fact that the measurement of the quantum state of an unknown quantum system modifies the system itself. In other words, a spy eavesdropping on a quantum communication channel cannot ...

AI Technical Summary

Problems solved by technology

The disadvantage of this implementation is that in order to implement the decoy state method an additional intensity modulator is required (compared to the implementation of the COW protocol)

An additional disadvantage of the system described by Lucamarini et al., 2013 is the need for polarization stabilization at the receiver, since polarization-dependent losses or incomplete stabilization introduce additional losses and complementary error possibilities

Images