Quantum Dynamical Phase Transition in a pair of interacting spins, double quantum dots and two level systems. Experiments and theory.
Horacio Miguel PASTAWSKI - (univ. Cordob
Mercredi 28/06/2006, 14h00
Bât. C5 P.421A, CEA-Grenoble


The talk, which will be presented at a tutorial level, focuses on the effect of the environment on the dynamical manipulation of charge and spin qubits in swapping gates such as the double quantum dot and coupled nucleus in NMR.  We found a critical value for the interaction with the environment which totally freezes the swapping through Quantum Zeno Effect which is quite analogous to the overdamped regime in an harmonic oscillator. The critical strength depends on the symmetry of the S-E interaction. The phenomenon also can be interpreted as a dynamical version of P. W. Anderson's exchange narrowing effect, which recently has received much attention in the context of Vacuum Rabi Oscillations. Part of the theory and the NMR experiments have been published recently in Journal of Chemical Physics.


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