Qutrit-based semi-quantum key distribution protocol

Michel Boyer, Matty Katz, Rotem Liss +1 more

Kento Yamada, Ryutaroh Matumoto

Ramona Wolf

Wajdi Sabah Abdul Razzaq

This paper presents two novel quantum key distribution (QKD) protocols operating in three-valued (qutrit-based) logic. Protocol I demonstrates a simplified QKD scheme that avoids quantum qubit transmission, relying instead on entangled qutrit pairs to achieve unconditional security between one sender and one receiver. Protocol II generalises this framework to n = 3^m receivers using a maximally entangled (m+n)-qutrit state. The key efficiency η = (n+1)/(n+m) exceeds 50% and improves with the number of users. Both protocols achieve unconditional security. This work constitutes the first reported QKD protocol designed natively for three-valued quantum logic.

R. Lalu Naik

Walter O. Krawec

A semi-quantum key distribution (SQKD) protocol allows two users A and B to establish a shared secret key that is secure against an all-powerful adversary E even when one of the users (e.g., B) is semi-quantum or classical in nature while the other is fully-quantum. A mediated SQKD protocol allows two semi-quantum users to establish a key with the help of an adversarial quantum server. We introduce the concept of a multi-mediated SQKD protocol where two (or more) adversarial quantum servers are used. We construct a new protocol in this model and show how it can withstand high levels of quantum noise, though at a cost to efficiency. We perform an information theoretic security analysis and, along the way, prove a general security result applicable to arbitrary MM-SQKD protocols. Finally, a comparison is made to previous (S)QKD protocols.