In the ongoing effort to make communications secure, Quantum Key Distribution (QKD) theoretically provides a solution – but to the delight of increasingly sophisticated hackers, falls short in real-world systems due to implementation deviating from mathematical models. A number of QKD variants – including Device-Independent Quantum Key Distribution (DIQKD) and the more recently introduced Measurement-Device-Independent Quantum Key Distribution (MDIQKD) – attempt to close the gap between theory and practice with varying degrees of success. These two variants differ in several ways, the most important being that DIQKD requires but unlike MDIQKD cannot easily achieve very high detection efficiency and low channel loss to yield secure keys, while MDIQKD, unlike DIQKD, does not rely on any ideal devices and can close the most vulnerable QKD security hole by removing all side-channels from the measurement unit. Nevertheless, previous MDIQKD systems have had limitations as well, such as limited distance and a low key rate of less than 0.1 bit/s.
Recently, however, scientists at the University of Science and Technology of China devised a de novo MDIQKD protocol and have developed a 75 MHz clock rate, fully automatic and highly stable system and superconducting nanowire single-photon detectors with detection efficiencies of more than 40%.
Read more at: Phys.org