Passive-state preparation in continuous-variable measurement-device-independent quantum key distribution
Dongyun Bai, Peng Huang, Hongxin Ma, Tao Wang, Guihua Zeng · Journal of Physics B Atomic Molecular and Optical Physics · 2019
Abstract Continuous-variable measurement-device-independent quantum key distribution (CV-MDI QKD) with Gaussian modulation, or with active state preparation, is immune to all detection-related security loopholes. Here, we first propose a scheme where Alice and Bob both passively prepare quantum states using a true thermal source, which is of lower cost and will contribute to the commercialization of CV-MDI QKD. In particular, Alice and Bob first split the output of a thermal source into two correlated modes via a beam splitter at their respective side. Then they measure one of the two modes using two conjugate homodyne detectors and transmit the other attenuated mode to Charlie independently for the Bell state measurement. Moreover, the homodyne detectors, with bright local oscillators, can act as a filter to selectively measure one single mode, which removes the rigid requirement of a single-mode thermal source. This specific conceptual scheme will contribute to the simplification of the experimental implementation of CV-MDI QKD.