# Groupe de Physique Statistique

## Equipe 106, Institut Jean Lamour

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### Séminaire de groupe

 Random quantum systems with long-range interactions Ferenc Iglói Wigner Research Centre for Physics, Budapest, HungaryInstitute of Theoretical Physics, Szeged University, Hungary lundi 08 juin 2015 , 10h25 Salle de séminaire du groupe de Physique Statistique We study the low-energy properties of the long-range random transverse-field Ising model in $d$-dimension having ferromagnetic interactions decaying as a power $d+\sigma$ of the distance. In particular we studied the system in $d=1$ using variants of the strong-disorder renormalization group method [1]. The critical behavior is found to be controlled by a strong-disorder fixed point with a {\it finite} dynamical exponent $z_c=d+\sigma$. Approaching the critical point, the correlation length diverges exponentially. In the critical point, the magnetization shows a $\sigma$-independent logarithmic finite-size scaling and the entanglement entropy satisfies the area law. Similar observations are found in higher dimensions, as well as for the long-range epidemic spreading (contact process) in a random environment [2].

[1] R. JuhÃ¡sz, I. A. KovÃ¡cs and F. IglÃ³i, EPL 107, 47008 (2014)
[2] R. JuhÃ¡sz, I. A. KovÃ¡cs and F. IglÃ³i, Phys. Rev. E 91, 032815 (2015)