In an essential step toward practical implementation of secure quantum-based communication, scientists have shown stable measurement-device-independent quantum key distribution, MDI-QKD, transmission over a new record of 170 kilometers.
QKD comes with unintelligible encryption by utilizing the quantum features of light to provide safe random keys between users for encrypting and decrypting online data. The measurement-device-independent QKD protocol is now the most practical and secure because it’s resistant to attacks directed at the detection devices that measure individual photons’ quantum features. Here is what you need to know.
Improving Security Over Elongated Lengths
Even if QKD has been confirmed over relatively long distances, it has been challenging to do this with high transmission rates while keeping everything safe. To overcome this thing, Qin Wang, from the Nanjing University of Posts and Telecommunications, and his team developed a new MDI-QKD transmission protocol that utilizes photons with three defined quantum states to encode data.
The regular MDI-QKD protocol can last through all possible detection loopholes. But, it still assumes perfect state preparation that can be a massive challenge in practice.
To keep everything safe against state-preparation flaws, some countermeasures have been put forward. So, a new method was proposed dubbed MDI-QKD with undefined sources by incorporating mismatched-basis information that is usually dismissed from the calculation of the phase-error rate.
The team developed a practical technique, in which not only an enhanced phase estimation procedure but also a simple three-state system is implemented to produce substantially increased performance. The researchers also utilized a state-of-art experimental setup for detection and encoding to show the new QKD proposal could transmit keys at higher rates and over longer lengths. Theoretical measurements proved that secure transmission could be possible over ranges up to 200 kilometers.
The recent work can be further developed by including the new proposed twin-field QKD protocols or the highly efficient decoy-state technique.
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