Karl Kraus (21 March 1938 – 9 June 1988) was a German theoretical physicist who made major contributions to the foundations of quantum physics.

In 1980 Kraus spent a sabbatical year at UT Austin with John Archibald Wheeler, Arno Böhm, George Sudarshan, William Wootters, and Wojciech Zurek.

The Kraus representation is based on a theorem of WF Stinespring about completely positive images of finite-dimensional C*-algebras.

[6] For a modern proof of the Kraus representation, which is based on a theorem of Man-Duen Choi[7] instead of Stinespring's set, see M. Nielsen, I.

[9] These decoherence theories have been combined with modern experiments, particularly those done by the groups of Serge Haroche (Paris) and Anton Zeilinger (Innsbruck, Vienna), in an attempt to use the measurement process in quantum theory to better understand relationship between quantum and classical world.