Quantum Key Distribution with Vacuum-One-Photon Qubits

摘要

We consider quantum key distribution (QKD) schemes in which signals are carried by light pulses in superposition states of the vacuum and single-photon states. The ratio K[1] of the number of securely transferred bits to the number of particles sent can be greater for these schemes than the standard schemes employing polarization or phase coding,suggesting a possibility of cost-effective QKD schemes. We present results of our calculation of the ratio K for several QKD schemes when vacuum-one-photon qubits are used as well as when polarization qubits are used.