Key rate available from incompatible mesurements in the BB84 protocol and the uncertainty principle

摘要

BB84量子鍵配送プロトコルにおいて送信基底と測定基底が異なる測定を行った部分から安全に取り出せrnる鍵レートの下界を導出する．さらに，不確定性原理を用いて，送信基底と測定基底が同一部分と異なる部分の両方かrnら同時に秘密鍵を得ることはできないことを示す．%We evaluate the amount of secret key that can be obtained from the incompatible measurements in the BB84 quantum key distribution protocol, in which measuring bases are different from transmitting bases. Moreover, the entropic uncertainty principle implies that one cannot extract the secret key from both compatible measurements and incompatible ones simultaneously.