No Arabic abstract
In Phys. Rev. Lett. 110, 219701 (2013) [arXiv:1211.0843] Billoire et al. criticize the conclusions of our Letter [Phys. Rev. Lett. 109, 177204 (2012), arxiv:1206.0783]. They argue that considering the Edwards-Anderson and Sherrington-Kirkpatrick models at the same temperature is inappropriate and propose an interpretation based on the replica symmetry breaking theory. Here we show that the theory presented in the Comment does not explain our data on the Edwards-Anderson spin glass and we stand by our assertion that the low-temperature behavior of the Edwards-Anderson spin glass model does not appear to be mean-field like.
A recent interesting paper [Yucesoy et al. Phys. Rev. Lett. 109, 177204 (2012), arXiv:1206:0783] compares the low-temperature phase of the 3D Edwards-Anderson (EA) model to its mean-field counterpart, the Sherrington-Kirkpatrick (SK) model. The authors study the overlap distributions P_J(q) and conclude that the two models behave differently. Here we notice that a similar analysis using state-of-the-art, larger data sets for the EA model (generated with the Janus computer) leads to a very clear interpretation of the results of Yucesoy et al., showing that the EA model behaves as predicted by the replica symmetry breaking (RSB) theory.
The Comment by Ha et al. [cond-mat/0603787] criticizes our recent result [Phys. Rev. Lett. 96, 038701 (2006)] that the contact process (CP) on uncorrelated scale-free (SF) networks does not behave according to heterogeneous mean-field (MF) theory. This claim is based in Gaussian ansatz that reproduces previously reported density fluctuations and numerical simulations for a particular value of the degree exponent $gamma$ that seem to fit the MF prediction for the density decay exponent $theta$ and a conjecture of the authors of the comment for the finite-size scaling exponente $alpha=beta/ u_perp$. By means of extensive simulations of the CP on random neighbors (RN) SF networks we show that the MF prediction for $theta4 is incorrect for small degree exponents, while the authors conjecture for $alpha$ is at best only approximately valid for the unphysical case of uncorrelated networks with cut-off $k_c sim N^{1/(gamma-1)}$, which can only be constructed in the RN version of SF networks. Therefore, the main conclusion of our paper [Phys. Rev. Lett. 96, 038701 (2006)], the invalidity of MF theory for real uncorrelated SF networks, remains unchallenged.
In the Edwards-Anderson model of spin glasses with a bimodal distribution of bonds, the degeneracy of the ground state allows one to define a structure called backbone, which can be characterized by the rigid lattice (RL), consisting of the bonds that retain their frustration (or lack of it) in all ground states. In this work we have performed a detailed numerical study of the properties of the RL, both in two-dimensional (2D) and three-dimensional (3D) lattices. Whereas in 3D we find strong evidence for percolation in the thermodynamic limit, in 2D our results indicate that the most probable scenario is that the RL does not percolate. On the other hand, both in 2D and 3D we find that frustration is very unevenly distributed. Frustration is much lower in the RL than in its complement. Using equilibrium simulations we observe that this property can be found even above the critical temperature. This leads us to propose that the RL should share many properties of ferromagnetic models, an idea that recently has also been proposed in other contexts. We also suggest a preliminary generalization of the definition of backbone for systems with continuous distributions of bonds, and we argue that the study of this structure could be useful for a better understanding of the low temperature phase of those frustrated models.
Reply to the Comment by L. Berthier and J.-P. Bouchaud, Phys. Rev. Lett. 90, 059701 (2003), also cond-mat/0209165, on our paper Phys. Rev. Lett. 89, 097201 (2002), also cond-mat/0203444
We study the off-equilibrium dynamics of the three-dimensional Ising spin glass in the presence of an external magnetic field. We have performed simulations both at fixed temperature and with an annealing protocol. Thanks to the Janus special-purpose computer, based on FPGAs, we have been able to reach times equivalent to 0.01 seconds in experiments. We have studied the system relaxation both for high and for low temperatures, clearly identifying a dynamical transition point. This dynamical temperature is strictly positive and depends on the external applied magnetic field. We discuss different possibilities for the underlying physics, which include a thermodynamical spin-glass transition, a mode-coupling crossover or an interpretation reminiscent of the random first-order picture of structural glasses.