Decoy state protocols are a useful tool for many quantum key distribution systems implemented with weak coherent pulses, allowing significantly better secret bit rates and longer maximum distances. In this paper we present a method to numerically fin
d optimal three-level protocols, and we examine how the secret bit rate and the optimized parameters are dependent on various system properties, such as session length, transmission loss, and visibility. Additionally, we show how to modify the decoy state analysis to handle partially distinguishable decoy states as well as uncertainty in the prepared intensities.
Advances in quantum physics and computational complexity threaten the security of present day cryptographic systems and have driven the development of quantum key distribution (QKD). Entangled quantum key distribution (EQKD) is a secure protocol that
is based on fundamental quantum mechanics and is not vulnerable to these threats. The primary figure of merit for QKD systems is ability to generate secret bits. However, to date, methods that have been developed to simulate the secret bit rate generation for EQKD systems have been limited by techniques that do not provide a complete description of the quantum state produced by the source. In this paper, we provide a complete description and comparison of the secret bit rate for continuous-wave and pulsed laser EQKD systems. In particular, we highlight the relevant Poissonian and thermal photon statistics that affect the EQKD secret bit rate and use practical system parameters and configurations to show regimes where one expects optimal performance for each case.
