Continuous variable quantum key distribution using post-selection with two qubit block protocol

Abstract

The research on Quantum Key Distribution(QKD) has been active since the proposal of BB84 protocol and the research on Continuous Variable QKD(CV QKD) has been active since the proposal of GG02 protocol. When GG02 was proposed, there was a significant limits that tolerable loss to share the quantum key is 3dB, meaning that the transmissible distance is much shorter than that of BB84. To overcome this limit, the post-selection technique was applied in [1]. Meanwhile, there is a protocol applying the multi-qubit, resulting in longer transmissible distance than other Discrete Variable QKD(CV QKD) protocols. We applied this concept into CV QKD using post-selection and performed & compared the result with CV QKD using post-selection protocol. In comparison, we calculated the secret key rate with a parameter related to signal modulation variance and results in maximum key rate at given transmissivity T.