Europhys. Lett.
Volume 67, Number 5, September 2004
Page(s) 700 - 706
Section General
Published online 01 August 2004
Europhys. Lett., 67 (5), pp. 700-706 (2004)
DOI: 10.1209/epl/i2004-10110-1

The information entropy of quantum-mechanical states

A. Stotland1, A. A. Pomeransky2, E. Bachmat3 and D. Cohen1

1  Department of Physics, Ben-Gurion University - Beer-Sheva 84105, Israel
2  Laboratoire de Physique Théorique, UMR 5152 du CNRS, Université Paul Sabatier 31062 Toulouse Cedex 4, France
3  Department of Computer Science, Ben-Gurion University - Beer-Sheva 84105, Israel

(Received 19 April 2004; accepted in final form 15 June 2004)

It is well known that a Shannon-based definition of information entropy leads in the classical case to the Boltzmann entropy. It is tempting to regard the von Neumann entropy as the corresponding quantum-mechanical definition. But the latter is problematic from the quantum information point of view. Consequently, we introduce a new definition of entropy that reflects the inherent uncertainty of quantum-mechanical states. We derive for it an explicit expression, and discuss some of its general properties. We distinguish between the minimum uncertainty entropy of pure states, and the excess statistical entropy of mixtures.

03.65.Ta - Foundations of quantum mechanics; measurement theory.
03.67.-a - Quantum information.

© EDP Sciences 2004