Geometric phases in a critical environment

FERNANDO C. LOMBARDO; PAULA I. VILLAR; FERNANDO CUCCHIETTI

Benasque

Conferencia; Quantum Coherence and Decoherence International Worskshop; 2010

We obtain a correction of the unitary geometric phaseby measuring the nonunitary evolution of the reduced density matrix of a spin one-halfcoupled to an environment. In particular we are interested in baths near a quantum phase transition, which areknown to induce strong decoherence. The experiments are done with a NMR quantum simulator, where weemulate qualitatively the influence of a critical environment using a simple one-qubit model.