Attacking a high-dimensional quantum key distribution system with wavelength-dependent beam splitter

Du Ge-Hai^{1, 2}, Li Hong-Wei^{1, 2, †}, Wang Yang^{1, 2}, Bao Wan-Su^{1, 2, ‡}

The final QBER as a function of coupling ratios r 1 and r 2 where r 1 and r 2 are coupling ratios corresponding to wavelengths λ 1 and λ 2 .