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4 papers
Maps on positive operators preserving Rényi type relative entropies and maximal -divergences
Marcell Gaál, Gergő Nagy
In this paper we deal with two quantum relative entropy preserver problems on the cones of positive (either positive definite or positive semidefinite) operators. The first one is…
On integral estimates of non-negative positive definite functions
Andrey Efimov, Marcell Gaal, Szilard Gy. Revesz
Let be arbitrary. We introduce the extremal quantities $$ G(\ell):=\frac{\sup_{f} \int_{-\ell}^{\ell} f\,dx}{\int_{-1}^1 f\,dx},\quad C(\ell):=\frac{\sup_{f} \sup_{a\in {\…
On certain generalized isometries of the special orthogonal group
Marcell Gaál
In this paper we explore the structure of certain generalized isometries of the special orthogonal group which are transformations that leave any member of a large class of…
Transformations on density operators and on positive definite operators preserving the quantum Rényi divergence
Marcell Gaál, Lajos Molnár
In a certain sense we generalize the recently introduced and extensively studied notion called quantum Rényi divergence (in another name, sandwiched Rényi relative entropy) and des…