Locking with three mutually unbiased bases
Manuel A. Ballester, Stephanie Wehner · CERN Document Server (European Organization for Nuclear Research) · 2006
We show that using more mutually unbiased bases does not always lead to a better locking effect. In particular, we prove that the optimal bound for the accessible information using three specific mutually unbiased bases is n/2, which is the same as can be achieved by using only two bases. Our result indicates that merely using mutually unbiased bases is not sufficient to achieve a strong locking effect, and we need to look for additional properties. We also prove an entropic uncertainty relation that may be of independent interest.