Institut de Physique Théorique - Orme des Merisiers, CEA Saclay
Real-Space Renormalization for pure and random quantum spin systems : application to the Shannon-Renyi entropies of the ground state wave function.
Abstract : After a general introduction on real-space renormalization in disordered systems, two explicit RG procedures will be discussed for the quantum Ising chain that displays a zero-temperature phase transition between a ferromagnetic phase and a paramagnetic phase :
(i) the self-dual block RG, introduced by Fernandez-Pacheco for the pure chain.
(ii) the Ma-Dasgupta-Fisher Strong Disorder RG, defined only for the random chain.
These RG procedures can be applied in particular to study the Shannon-Renyi entropies of the ground state wave function : the singularity of the leading extensive term at criticality will be discussed both for the pure and for the random chain.