Spin glasses are a longstanding model for the sluggish dynamics that appears at the glass transition. The enjoy a privileged status in this context, as they provide the simplest model system both for theoretical and experimental studies of a glassy dynamics. However, in spite of forty years of intensive investigation, spin glasses still pose a formidable challenge to theoretical, computational and experimental physics. The main difficulty lies in their incredibly slow dynamics. A recent breakthrough has been made possible by our custom-built computer, Janus. For specific problems in Statistical Physics, Janus outperforms conventional computers by three orders of magnitude. It was designed and built in a collaboration formed by five universities in Spain and Italy.

After a general introduction to spin glasses, the talk will focus on the new physics unearthed by Janus. In particular, we recall our numerical study of the nonequilibrium dynamics of the Ising Spin Glass, for a time that spans eleven orders of magnitude, thus approaching the experimentally relevant scale (i.e. seconds) [1]. We have also studied the equilibrium properties of the spin-glass length, with an emphasis on the quantitative matching between nonequilibrium and equilibrium correlation functions [2]. Last but not least, we have clarified the existence of a glass transition in the presence of a magnetic field [3] (the so-called de Almeida-Thouless line).

[1] Janus collaboration: F. Belleti et al., Phys. Rev. Lett. 101 (2008) 157201, and J. Stat. Phys. 135, 1121-1158 (2009)

[2] Janus Collaboration: R. A. Baños et al.,Phys. Rev. Lett. 105, 177202 (2010) and J. Stat. Mech. (2010) P06026.

[3] Janus Collaboration: R. A. Baños et al., arXiv:1202.5593 (PNAS 2012, in press).