1202.3822 (Won-Young Hwang et al.)

No-signaling Quantum Key Distribution: A Straightforward Approach    [PDF]

Won-Young Hwang, Joonwoo Bae, Nathan Killoran

We outline a straightforward approach for obtaining a secret key rate using
only no-signaling constraints. Assuming an individual attack, we consider all
possible joint probabilities. First we suppose temporarily that Eve (an
eavesdropper) is restricted to binary outcomes. We impose constraints due to
the no-signaling principle and given measurement outcomes. Within the remaining
space of joint probabilities, by using convex optimization, we find the maximum
mutual information $I_{BE}^{max}(2)$ between Bob (a user) and a
binary-restricted Eve. Then, by considering a certain coarse graining mapping,
we show how to get a bound on $I_{BE}^{max}$, the maximal mutual information
between Bob and Eve, whose number of outcomes is not restricted, from the
quantity $I_{BE}^{max}(2)$. Using the Csisz\'ar-K\"orner formula and the
calculated bound, we obtain the key generation rate.

View original: http://arxiv.org/abs/1202.3822