Werner, R.F.
On the concentration of quantum states in phase space
(38K, Plain TeX)

ABSTRACT.  Let $E(x)$, for $x$ in a $2d$-dimensional phase space, be an 
irreducible Weyl system, and $\Phi:{\bf R}\sp+\to{\bf R}\sp+$ a 
convex function with $\Phi(0)=0$. We discuss the maximum of 
$\int dx\ \Phi\bigl(\vert\langle\phi,E(x)\psi\rangle\vert\sp2\bigr)$ 
with respect to unit vectors $\phi,\psi$. When $\Phi(t)=t\sp p$ with 
$1<p<\infty$ the maximum is attained if and only if $\phi$ and 
$\psi$ are coherent states with respect to the same quadratic form. 
We show that this statement is not correct for more general convex 
functions $\Phi$.