The Open Problems in Quantum Information page that was started by Reinhard Werner at TU Braunschweig and then moved to U Hannover (here the last recorded version (May 2022) in the Internet Archive) is now maintained here by a team at IQOQI Vienna.

## Suggested further problems

We, the administrators of the Hannover open problem pages, will periodically check these contributions and move the ones we find most interesting to the main list.

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Below is a very short sample problem with the main sections.

### Maximal rate function for estimation

#### Problem

Show that there is no state estimation procedure whose large deviation rate function is equal to the relative entropy.

#### Background

It is known from hypothesis testing that the relative entropy is an upper bound to the rate function.

#### Literature

- M. Keyl, Quantum state estimation and large deviations,