Reference-free-independent quantum key distribution immune to detector side channel attacks

Usually, a shared reference frame is indispensable for practical quantum key distribution (QKD) systems. As a result, most QKD systems need active alignment of reference frame due to the unknown and slowly variances of reference frame introduced by environment. Quite interestingly, reference-free-independent (RFI) QKD can generate secret-key bits without alignment of reference frame. However, RFI QKD may be still vulnerable to detector side channel attacks. Here, we propose a new RFI QKD protocol, in which all detector side channels are removed. Furthermore, our protocol can still tolerate unknown and slow variance of reference frame without active alignment. And a numerical simulation shows that long security distance is probable in this protocol.