Dirk Schlingemann, Workshop on: QUANTUM INFORMATION PROCESSING FOR QUANTUM COMMUNICATIONS

Workshop on
Quantum Information and Foundations of Quantum Mechanics The Information-Disturbance Tradeoff and the Continuity of Stinespring's Representation
aula DOTTORATO - MERCOLedì 17 MAGGIO ore 11.00
	DIRK SCHLINGEMANN, Technical University of Braunschweig
>VITAE: 1987-1996: Study in Physics at the University of Hamburg (Germany), Diploma and PhD in the field of "algebraic quantum field theory" at the II. Institute for Theoretical Physics in the group of Klaus Fredenhagen. 1997-1999: Research project in quantum field theory an euclidean field theory at the Erwin Schrödinger International Institute for Mathematical Physics (ESI), Vienna associated with the group of Jakob Yngvason at the Institut für Theoretische Physik, University Vienna. Funding by the DFG, the ESI and the Jubiläumsfonds der Oesterreichischen Nationalbank. Since 2000: Research associate at the Institut für Mathematische Physik, Technical University Braunschweig, in the quantum information theory research group of Reinhard Werner. Funding by the DFG and EQUIP.
Abstract
	Stinespring's dilation theorem is the basic structure theorem for quantum channels: it states that any quantum channel arises from a unitary evolution on a larger system. Here we prove a continuity theorem for Stinespring's dilation: if two quantum channels are close in cb-norm, then it is always possible to find unitary implementations which are close in operator norm, with dimension-independent bounds. This result generalizes Uhlmann's theorem from states to channels and allows to derive a formulation of the information-disturbance tradeoff in terms of quantum channels, as well as a continuity estimate for the no-broadcasting theorem. We briefly discuss further implications for quantum cryptography, thermalization processes, and the black hole information loss puzzle.