  The concept of quantum phase space offers a view on quantum mechanics, which
is different from the standard Hilbert space approach, but which more closely
resembles the classical phase space. Due to the properties of quantum mechanics
there are several equivalent quantum phase space descriptions, and one cannot
always prefer one or another as they all have certain merits and drawbacks. For
example, the Husimi-Kano Q function is a probability distribution and thus
gives rise to entropic quantities, namely the Renyi-Wehrl entropies, of which
several properties are known. The Wigner function, on the other hand, has an
easier physical explanation, but may take negative values. In this article, we
investigate entropic measures of localisation for a state in quantum phase
space by using the Beckner-Brascamp-Lieb inequality to relate different
phase-space functions.
