1. Introduction
The first quantum key distribution (QKD) protocol, BB84 protocol[1], is proven secure in defending the formidable decryption ability in the approaching era of quantum computing[2–4]. In this decade, it is significant to narrow down the gap between ideal unconditional security and imperfect realistic devices. From the viewpoint of Eve, there are two main types of vulnerabilities to security, which are the light source at the transmitter and the detector at receiver[5–7]. As a countermeasure, the decoy state protocol can circumvent the photon number splitting attack, and a weak coherent source can be applied in QKD applications[8–10]. In addition, measurement device independent (MDI) protocol[11] can remove all the side channels’ loopholes aiming at the measurement devices. Besides, MDI-QKD realizes a star-type quantum network and improves the ability of long distance transmission[12–14]. With the important practical prospect, it has been experimentally demonstrated to break through the 400 km fiber transmission[15] and applied in the chip-based platform as well as the free-space channel[16–19].