Quantum Computation and Information Seminar 

01/07/2008, 14:15 — 15:15 — Room P6, Mathematics Building
Nikola Paunkovic, SQIG, Instituto de Telecomunicações

Macroscopic Distinguishability between Quantum States defining different Phases of Matter

We show that fidelity, a measure of state distinguishability, used in quantum information and computation, can be efficiently used as a tool to detect some macroscopic phase transitions and we establish its relation to standard many-body properties. In particular, we make the analytical study of the Hubbard-Stoner model of itinerant magnetism and the BCS model of superconductivity, and make the numerical study of an impurity in a superconductor film.