2 citations · 3 across the 6 of their papers we have counts for
6 papers
On the additivity of the minimum output entropy
Norbert Riedel
It is shown that for real finite dimensional Hilbert spaces the additivity property of the minimum output entropy for quantum channels is always true.
On the Markoff Equation
Norbert Riedel
A triple (a, b, c) of positive integers is called a Markoff triple iff it satisfies the Diophantine equation a2+b2+c2=abc . Recasting the Markoff tree, whose vertices are Markoff t…
Markoff Equation and Nilpotent Matrices
Norbert Riedel
A triple (a,b,c) of positive integers is called a Markoff triple iff it satisfies the diophantine equation a2 + b2 + c2 = abc . Recasting the Markoff tree, whose vertices are Marko…
Persistence of gaps in the spectrum of certain almost periodic operators
Norbert Riedel
It is shown that for any irrational rotation number and any admissible gap labelling number the almost Mathieu operator (also known as Harper's operator) has a gap in its spectrum…
Exponentially decaying eigenvectors for certain almost periodic operators
Norbert Riedel
For certain one-dimensional Schroedinger-type difference operators with a complex potential, a "complete" set of exponentially decaying eigenvectors is shown to exist. "Completenes…
Absence of Cantor spectrum for a class of Schrödinger operators
Norbert Riedel
It is shown that the complete localization of eigenvectors for the almost Mathieu operator entails the absence of Cantor spectrum for this operator.