Here we present two new schemes for quantum key distribution (QKD) which neither require entanglement nor require an ideal single photon source. Thus, the proposed protocols can be implemented using realistic single photon sources which are commercially available. The schemes are shown to be secure against multiple attacks (e.g., intercept resend attack and a class of collective attacks). Bounds on the key rate are obtained and it is shown that by applying a certain type of classical pre-processing, the tolerable error limit can be increased. A trade-off between quantum resources used and information revealed to Eve is observed and it is shown that by using slightly more quantum resources it is possible to design protocols having higher efficiency compared to a protocol of the same family that uses relatively lesser amount of quantum resources. Specifically, in our case, SARG04 protocol is a protocol of the same family and it is clearly shown that the proposed protocols can provide higher efficiency compared to SARG04 at the cost of consumption of more quantum resources. Further, it is shown that the critical distances for the proposed protocols under photon number splitting (PNS) type attacks are higher than the critical distances obtained for BB84 and SARG04 protocols implemented under similar situation.

翻译：本文提出了两种新的量子密钥分发（QKD）方案，它们既不需要纠缠，也不需要理想的单光子源。因此，所提出的协议可以利用市售的实用化单光子源实现。研究表明，这些方案能够抵御多种攻击（例如，截获重发攻击和一类集体攻击）。获得了密钥率界限，并证明通过应用某种类型的经典预处理，可容忍的错误极限得以提高。观察到所使用的量子资源与泄露给Eve的信息之间存在权衡关系，并且表明，通过使用稍多的量子资源，可以设计出比同一家族中使用相对较少量子资源的协议具有更高效率的协议。具体而言，在我们的研究中，SARG04协议属于同一家族，并且明确指出，所提出的协议能够以消耗更多量子资源为代价，提供比SARG04更高的效率。此外，研究表明，所提出的协议在光子数分裂（PNS）类型攻击下的临界距离高于在类似情况下实施的BB84和SARG04协议所获得的临界距离。