Effect of source statistics on utilizing photon entanglement in quantum key distribution

The effect of photon-pair generation rate on quantum entanglement is analyzed. Two techniques of producing polarization entanglement were compared: a cw-pumped spontaneous parametric down-conversion and a biexciton decay in a quantum dot. We made a comparison of the reconstructed entangled states in terms of performance under device-independent quantum key distribution. We found that the secure key rate of down-converted photon pairs is limited to 0.029 bits per detection window due to intrinsic multiphoton contributions. We also report that there exists one optimum gain for down-conversion sources. Finally, we discuss the achievable secure key rate of quantum dots limited mainly by photon collection efficiency.