Security of differential phase shift QKD from relativistic principles

Understand

The design of quantum protocols for secure key generation poses many challenges: On the one hand, they need to be practical concerning experimental realisations.

• On the other hand, their theoretical description must be simple enough to allow for a security proof against all possible attacks.
• Often, these two requirements are in conflict with each other, and the differential phase shift (DPS) QKD protocol exemplifies these difficulties: It is designed to be implementable with current optical telecommunication technology, which, for this protocol, comes at the cost that many standard security proof techniques do not apply to it.
• After about 20 years since its invention, this work presents the first full security proof of DPS QKD against general attacks, including finite-size effects.