Hi all,

this week Moritz Bürgi will talk about “Reference Systems in Quantum Cryptography”, see below for the abstract. The talk will take place on Thursday at 11:00 in HIT E 41.1.

Best, Ladina

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Title:

The Role of Reference Systems in Quantum Cryptography

Abstract:

Quantum mechanics is conventionally formulated with respect to a classical frame of reference, meaning that states and measurements are defined relative to a physical system which is treated classically. The existence of such a classical reference frame is thus implicitly assumed whenever we put quantum mechanics to use, for instance in quantum key distribution (QKD). We make the reference systems involved explicit and include them in our mathematical description. However, any physical systems, including those used as a reference, are ultimately quantum mechanical, a feature which has been ignored in QKD security proofs. We ask whether this inclusion poses any risks for security established in security proofs in conventional QKD by considering a simple prepare and measure protocol. In such a protocol we focus on the reference frame alignment phase of the parties involved and the subsequent state preparation phase. Based on a set of assumptions we motivate, we show that an eavesdropper can only establish correlations with the prepared states through the reference systems. We argue that security is not immediately compromised in the state preparation phase by explicitly considering the reference systems.