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© 2008 American Physical Society. This work has been partially supported by MEC through Contracts No. FIS2004-01399, No. FIS2006-08533-C03, No. FIS2007-60977 and by CAM and BSCH. Computer time was obtained at BIFI, UCM, UEX, and, mainly, in the Mare Nostrum. The authors thankfully acknowledge the computer resources and technical expertise provided by the Barcelona Supercomputing Center., We present the first detailed numerical study in three dimensions of a first-order phase transition that remains first order in the presence of quenched disorder (specifically, the ferromagnetic-paramagnetic transition of the site-diluted four states Potts model). A tricritical point, which lies surprisingly near the pure-system limit and is studied by means of finite-size scaling, separates the first-order and second-order parts of the critical line. This investigation has been made possible by a new definition of the disorder average that avoids the diverging-variance probability distributions that plague the standard approach. Entropy, rather than free energy, is the basic object in this approach that exploits a recently introduced microcanonical Monte Carlo method., MEC (Spain), CAM (Spain), BSCH, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2010 The American Physical Society. We thank Federico Ricci-Tersenghi for discussions. Computations have been carried out in PC clusters at BIFI and DFTI-UCM. We have been partly supported by MICINN, Spain through Research Contracts No. FIS2006-08533 and No. FIS2009-12648-C03 and by UCM-Banco de Santander through Grant No. GR58/08. B.S. was supported by the FPU program Spain., We present a mean field model for spin glasses with a natural notion of distance built in, namely, the Edwards-Anderson model on the diluted D-dimensional unit hypercube in the limit of large D. We show that finite D effects are strongly dependent on the connectivity, being much smaller for a fixed coordination number. We solve the nontrivial problem of generating these lattices. Afterward, we numerically study the nonequilibrium dynamics of the mean field spin glass. Our three main findings are the following: i the dynamics is ruled by an infinite number of time sectors, ii the aging dynamics consists of the growth of coherent domains with a nonvanishing surface-volume ratio, and iii the propagator in Fourier space follows the p4 law. We study as well the finite D effects in the nonequilibrium dynamics, finding that a naive finite size scaling ansatz works surprisingly well., Ministerio de Ciencia e Innovación (MICINN), UCM-Banco de Santander, FPU program, Spain, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2011 American Physical Society. Artículo firmado por 23 autores. Janus has been funded by European Union (Fondo Europeo de Desarrollo Regional) funds, by Diputación General de Aragón (Spain), by a Microsoft Award-Sapienza-Italy, and by Eurotech. We acknowledge partial financial support from Ministerio de Ciencia e Innovación, Spain (Contracts No. FIS2009-12648-C03, No. FIS2010-16587, and No. TEC2010- 19207), Junta de Extremadura (GR10158), UEx (ACCVII-08), and from UCM-Banco de Santander (GR32/10-A/910383). D. Íñiguez is supported by the Government of Aragon through a Fundación ARAID contract. B. Seoane and D. Yllanes are supported by the Formación del Profesorado Universitario program (Ministerio de Educación, Spain)., We study the sample-to-sample fluctuations of the overlap probability densities from large-scale equilibrium simulations of the three-dimensional Edwards-Anderson spin glass below the critical temperature. Ultrametricity, stochastic stability, and overlap equivalence impose constraints on the moments of the overlap probability densities that can be tested against numerical data. We found small deviations from the Ghirlanda Guerra predictions, which get smaller as system size increases. We also focus on the shape of the overlap distribution, comparing the numerical data to a mean-field-like prediction in which finite-size effects are taken into account by substituting delta functions with broad peaks., Ministerio de Ciencia e Innovación (MICINN), Junta de Extremadura, Spain, UEx, UCM-Banco de Santander, Government of Aragon through a Fundación ARAID, Formación del Profesorado Universitario program (Ministerio de Educación, Spain), Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2013 Elsevier B.V. Artículo firmado por 24 autores. We warmly acknowledge the excellent work done by the Janus II team at Link Engineering. In particular we thank Pietro Lazzeri, Pamela Pedrini, Roberto Preatoni, Luigi Trombetta and Alessandro Zambardi for their professional and enthusiastic work. The Janus II project was supported by the European Regional Development Fund (ERDF/2007-2013, FEDER project UNZA08-4E-020); by the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013, ERC grant agreement no. 247328); by the MICINN (Spain) (contracts FIS2012-35719-C02, FIS2010-16587); by Junta de Extremadura (contract GR101583); by the Italian Ministry of Education and Research (PRIN Grant 2010HXAW77 007)., This paper describes the architecture, the development and the implementation of Janus II, a new generation application-driven number cruncher optimized for Monte Carlo simulations of spin systems (mainly spin glasses). This domain of computational physics is a recognized grand challenge of high-performance computing: the resources necessary to study in detail theoretical models that can make contact with experimental data are by far beyond those available using commodity computer systems. On the other hand, several specific features of the associated algorithms suggest that unconventional computer architectures – that can be implemented with available electronics technologies – may lead to order of magnitude increases in performance, reducing to acceptable values on human scales the time needed to carry out simulation campaigns that would take centuries on commercially available machines. Janus II is one such machine, recently developed and commissioned, that builds upon and improves on the successful JANUS machine, which has been used for physics since 2008 and is still in operation today. This paper describes in detail the motivations behind the project, the computational requirements, the architecture and the implementation of this new machine and compares its expected performances with those of currently available commercial systems., Unión Europea. FP7, Ministerio de Ciencia e Innovación (MICINN), European Regional Development Fund, Junta de Extremadura (Spain), Italian Ministry of Education and Research, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 1998 Elsevier Science B.V. We thank the CICyT (contracts AEN93-0604, AEN96-1634) for partial financial support, especially for the use of dedicated Pentium Pro machines on which we have carried out the simulations. JJRL is granted by EC HMC (ERBFMBICT950429). We also acknowledge to E. Luijten for pointing out the right scaling of the Binder cumulant in the pure case., Using finite-size scaling techniques, we study the critical properties of the site-diluted Ising model in four dimensions. We carry out a high-statistics Monte Carlo simulation for several values of the dilution. The results support the perturbative scenario: there is only the Ising fixed point with large logarithmic scaling corrections. We obtain, using the Perturbative Renormalization Group, functional forms for the scaling of several observables that are in agreement with the numerical data., CICyT, Spain, EC HMC, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2000 Elsevier Science B.V. This work was triggered during a discussion with F. Guinea to whom we are indebted for many suggestions, discussions and bibliographical help. The numerical calculations have being carried-out in the RTNN machines at the universities of Zaragoza and Complutense de Madrid. This work has been partially supported by CICYT, contracts AEN97- 1680,1693,1708., We study the linear response to an external electric field of a system of fermions in a lattice at zero temperature. This allows to measure numerically the Euclidean conductivity which turns out to be compatible with an analytical calculation for free fermions. The numerical method is generalizable to systems with dynamical interactions where no analytical approach is possible., CICYT, Spain, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2009 The American Physical Society. The CPU time used was 1.3 106 hours at CINECA through the EU DEISA initiative, 4.7 106 hours at the Mare Nostrum, 106 hours at Caesaraugusta, and 105 hours at the Hierarchical Systems Research Foundation. We were partly supported by MICINN Spain, research Contract No. FIS2006-08533-C03. The authors thankfully acknowledge the computer resources, technical expertise, and assistance provided by the staff at the Red Española de Supercomputación–Barcelona Supercomputing Center and at CINECA., We have investigated the phase transition in the Heisenberg spin glass using massive numerical simulations to study very large sizes, 483. A finite-size scaling analysis indicates that the data are compatible with the most economical scenario: a common transition temperature for spins and chiralities., Ministerio de Ciencia e Innovación (MICINN), Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2001 American Physical Society. We are thankful for helpful conversations to L. Brey, J. Fontcuberta, G. Gómez-Santos, C. Simon, J. M. De Teresa, and especially to R. Ibarra. V.M.-M. acknowledges the financial support of MEC. The Monte Carlo simulations have been carried out in RTNN computers at Zaragoza and Madrid. We acknowledge financial support from Grant Nos. PB96-0875, AEN97-1680, AEN97-1693, AEN99-0990 (MEC, Spain), and (07N/0045/98) (C. Madrid)., It is shown that the double-exchange Hamiltonian, with weak antiferromagnetic interactions, has a rich variety of first-order transitions between phases with different electronic densities and/or magnetizations. The paramagnetic-ferromagnetic transition moves towards lower temperatures, and becomes discontinuous as the relative strength of the double-exchange mechanism and antiferromagnetic coupling is changed. This trend is consistent with the observed differences between compounds with the same nominal doping, such as La_(2/3)Sr_(1/3)MnO_(3) and La_(2/3)Ca_(1/3)MnO_(3). Our results suggest that, in the low doping regime, a simple magnetic mechanism suffices to explain the main features of the phase diagram., MEC, Spain, C. Madrid, Spain, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

©2016 American Physical Society. This work was partially supported by the Ministerio de Economía y Competitividad (MINECO, Spain) through Grants No. FIS2012-35719-C02 and No. FIS2013-42840-P, and by the Junta de Extremadura (Spain), with partial contribution by the European Union (FEDER) through Grant No. GRU10158., We use finite size scaling to study Ising spin glasses in two spatial dimensions. The issue of universality is addressed by comparing discrete and continuous probability distributions for the quenched random couplings. The sophisticated temperature dependency of the scaling fields is identified as the major obstacle that has impeded a complete analysis. Once temperature is relinquished in favor of the correlation length as the basic variable, we obtain a reliable estimation of the anomalous dimension and of the thermal critical exponent. Universality among binary and Gaussian couplings is confirmed to a high numerical accuracy., Ministerio de Economía y Competitividad (MINECO)/FEDER, Junta de Extremadura, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2008 The American Physical Society. Artículo firmado por 21 autores. We corresponded with M. Hasenbusch, A. Pelissetto, and E. Vicari. Janus was supported by EU FEDER funds (UNZA05-33-003, MEC-DGA, Spain), and developed in collaboration with ETHlab. We were partially supported by MEC (Spain), through Contracts No. FIS2006-08533, FIS2007-60977, FPA2004-02602, TEC2007-64188; by CAM (Spain), and by Microsoft, We study numerically the nonequilibrium dynamics of the Ising spin glass, for a time spanning 11 orders of magnitude, thus approaching the experimentally relevant scale (i.e., seconds). We introduce novel analysis techniques to compute the coherence length in a model-independent way. We present strong evidence for a replicon correlator and for overlap equivalence. The emerging picture is compatible with noncoarsening behavior., EU FEDER funds, MEC (Spain), CAM (Spain), Microsoft, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2002 American Physical Society. We thank P. A. Algarabel, J. Blasco, J. García, R. Ibarra, J. M. de Teresa, and especially Domingo González, for discussions. The authors acknowledge financial support from CICyT (Spain) through Grant Nos. PB96-0875, AEN99- 0990, FPA2000-0956, and FPA2000-1252. V.M.-M. was supported by E.C. Contract No. HPMF-CT-2000-00450., Considering the disorder caused in manganites by the substitution Mn→Fe or Ga, we accomplish a systematic study of doped manganites begun in previous papers. To this end, a disordered model is formulated and solved using the variational mean-field technique. The subtle interplay between double exchange, superexchange, and disorder causes similar effects on the dependence of T_(C) on the percentage of Mn substitution in the cases considered. Yet, in La_(2/3)Ca_(1/3)Mn_(1-y)Ga_(y)O_(3) our results suggest a quantum critical point (QCP) for y ≈ 0.1–0.2, associated to the localization of the electronic states of the conduction band. In the case of La_(x)Ca_(x)Mn_(1-y)Fe_(y)O_(3) (with x = 1/3,3/8) no such QCP is expected., CICyT (Spain), E.C., Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2010 IOP Publishing Ltd and SISSA. Artículo firmado por 21 autores. Janus has been funded by European Union (FEDER) funds, Diputación General de Aragón (Spain), by a Microsoft Award - Sapienza - Italy, and by Eurotech. We were partially supported by MICINN (Spain), through contracts No. TEC2007-64188, FIS2006-08533-C03, FIS2007-60977, FIS2009-12648-C03 and UCM-Banco de Santander. D. Yllanes and B. Seoane are FPU Fellow (Spain). S.P.-G. was supported by FECYT (Spain). The authors would like to thank the Arénaire team, especially J. Detrey and F. de Dinechin for the VHDL code of the logarithm function 19., We study the 3D Disordered Potts Model with p = 5 and p = 6. Our numerical simulations (that severely slow down for increasing p) detect a very clear spin glass phase transition. We evaluate the critical exponents and the critical value of the temperature, and we use known results at lower p values to discuss how they evolve for increasing p. We do not find any sign of the presence of a transition to a ferromagnetic regime., Ministerio de Ciencia e Innovación (MICINN), European Union (FEDER), Diputación General de Aragón (Spain), Microsoft Award - Sapienza - Italy, Eurotech, UCM-Banco de Santander, FPU Fellow (Spain), FECYT (Spain), Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 1998 The American Physical Society. We are grateful to Dave Belanger for calling our attention to relevant experimental work. The computations have been carried out using the RTNN machines at Universidad de Zaragoza and Universidad Complutense de Madrid. We acknowledge CICyT for partial financial support (AEN97-1708 and AEN97-1693). J.J.R.L. is granted by EC HMC (ERBFMBICT950429)., We study the phase diagram of the site-diluted Ising model in a wide dilution range, through Monte Carlo simulations and finite-size scaling techniques. Our results for the critical exponents and universal cumulants turn out to be dilution independent, but only after a proper infinite volume extrapolation, taking into account the leading corrections-to-scaling terms., CICyT, Spain, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2012 National Academy of Sciences. Artículo firmado por 22 autores. We thank Davide Rossetti for introducing us to the handling of the 128-bit registers. We acknowledge partial financial support from Ministerio de Ciencia e Innovación (MICINN), Spain, (contract nos. FIS2009-12648-C03, FIS2010-16587, TEC2010-19207), from Universidad Complutense de Madrid (UCM)-Banco de Santander (GR32/10-A/910383), from Junta de Extremadura, Spain (contract no. GR10158), and from Universidad de Extremadura (contract no. ACCVII-08). B.S. and D.Y. were supported by the Formación de Profesorado Universitario (FPU) program (Ministerio de Educación, Spain); R.A.B. and J.M.-G. were supported by the Formación de Personal Investigador (FPI) program (Diputación de Aragón, Spain); finally J.M.G.-N. was supported by the FPI program (Ministerio de Ciencia e Innovación, Spain)., Spin glasses are a longstanding model for the sluggish dynamics that appear at the glass transition. However, spin glasses differ from structural glasses in a crucial feature: they enjoy a time reversal symmetry. This symmetry can be broken by applying an external magnetic field, but embarrassingly little is known about the critical behavior of a spin glass in a field. In this context, the space dimension is crucial. Simulations are easier to interpret in a large number of dimensions, but one must work below the upper critical dimension (i.e., in d < 6) in order for results to have relevance for experiments. Here we show conclusive evidence for the presence of a phase transition in a four-dimensional spin glass in a field. Two ingredients were crucial for this achievement: massive numerical simulations were carried out on the Janus special-purpose computer, and a new and powerful finite-size scaling method., Ministerio de Ciencia e Innovación (MICINN), Universidad Complutense de Madrid (UCM)-Banco de Santander, Junta de Extremadura, Spain, Universidad de Extremadura, Spain, Formación de Profesorado Universitario (FPU) program (Ministerio de Educación, Spain), Formación de Personal Investigador (FPI) program (Diputación de Aragón, Spain), FPI program (Ministerio de Ciencia e Innovación, Spain), Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2007 Elsevier B.V. Artículo firmado por 18 autores. The help of G. Poli in the development of the IANUS Ethernet interface is warmly acknowledged., We describe the hardwired implementation of algorithms for Monte Carlo simulations of a large class of spin models. We have implemented these algorithms as VHDL codes and we have mapped them onto a dedicated processor based on a large FPGA device. The measured performance on one such processor is comparable to O(100) carefully programmed high-end PCs: it turns out to be even better for some selected spin models. We describe here codes that we are currently executing on the IANUS massively parallel FPGA-based system., Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

©2016 American Physical Society. We are grateful to D. Yllanes and, especially, to L.A. Fernández for substantial help during several parts of this work. We also thank M. Picco and N. Sourlas for reading the manuscript. We were partly supported by MINECO, Spain, through research Contract No. FIS2012-35719-C02-01. Significant allocations of computing time were obtained in the clusters Terminus and Memento (BIFI). N.G.F. acknowledges financial support from a Royal Society Research Grant under No. RG140201 and from a Research Collaboration Fellowship Scheme of Coventry University., It was recently shown [Phys. Rev. Lett. 110, 227201 (2013)] that the critical behavior of the random-field Ising model in three dimensions is ruled by a single universality class. This conclusion was reached only after a proper taming of the large scaling corrections of the model by applying a combined approach of various techniques, coming from the zero-and positive-temperature toolboxes of statistical physics. In the present contribution we provide a detailed description of this combined scheme, explaining in detail the zero-temperature numerical scheme and developing the generalized fluctuation-dissipation formula that allowed us to compute connected and disconnected correlation functions of the model. We discuss the error evolution of our method and we illustrate the infinite limit-size extrapolation of several observables within phenomenological renormalization. We present an extension of the quotients method that allows us to obtain estimates of the critical exponent a of the specific heat of the model via the scaling of the bond energy and we discuss the self-averaging properties of the system and the algorithmic aspects of the maximum-flow algorithm used., Ministerio de Economía y Competitividad (MINECO), Royal Society (Reino Unido), Coventry University, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 1997 IOP Publishing Ltd. We thank to the CICyT (contracts AEN94-0218, AEN96-1634) for partial financial support. JJRL is granted by EC HMC (ERBFMBICT950429)., We study the site-diluted Ising model in two dimensions with Monte Carlo simulations. Using finite-size scaling techniques we compute the critical exponents observing deviations from the pure Ising ones. The differences can be explained as the effects of logarithmic corrections, without requiring to change the Universality Class., CICyT, Spain, EC HMC, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2010 The American Physical Society. Artículo firmado por 21 autores. The Janus computer was funded by EU FEDER (UNZA05 33-003, MEC-DGA, Spain) and developed in collaboration with ETHlab. We were partially supported by MICINN (Spain), through Contracts No. TEC2007- 64188, No. FIS2007-60977, No. FIS2009-12648-C03, by Junta de Extremadura (GRU09038), and by UCM-Banco de Santander. B. S. and D. Y. were supported by the FPU program (Spain) and SPG by FECYT (Spain)., We numerically study the aging properties of the dynamical heterogeneities in the Ising spin glass. We find that a phase transition takes place during the aging process. Statics-dynamics correspondence implies that systems of finite size in equilibrium have static heterogeneities that obey finite-size scaling, thus signaling an analogous phase transition in the thermodynamical limit. We compute the critical exponents and the transition point in the equilibrium setting, and use them to show that aging in dynamic heterogeneities can be described by a finite-time scaling ansatz, with potential implications for experimental work., Ministerio de Ciencia e Innovación (MICINN), EU FEDER, MEC-DGA, Spain, Junta de Extremadura, Spain, UCM-Banco de Santander, FPU program (Spain), SPG by FECYT (Spain), Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2005 The American Physical Society. It is a pleasure to thank F. Guinea for useful conversation at the beginning of this work. We have maintained interesting discussions with A. Pelissetto regarding the large-N approximation. This work has been partially supported through research contracts FPA2001-1813, FPA2000-0956, BFM2001-0718, BFM2003-8532, PB98-0842 sMCyTd and HPRN-CT-2002-00307 sEUd. We have used the PentiumIV cluster RTN3 at the Universidad de Zaragoza for the simulations. S.J. was supported by DGA., The phase diagram of the simplest approximation to double-exchange systems, the bosonic double-exchange model with antiferromagnetic (AFM) superexchange coupling, is fully worked out by means of Monte Carlo simulations, large-N expansions, and variational mean-field calculations. We find a rich phase diagram, with no first-order phase transitions. The most surprising finding is the existence of a segmentlike ordered phase at low temperature for intermediate AFM coupling which cannot be detected in neutron-scattering experiments. This is signaled by a maximum (a cusp) in the specific heat. Below the phase transition, only short-range ordering would be found in neutron scattering. Researchers looking for a quantum critical point in manganites should be wary of this possibility. Finite-size scaling estimates of critical exponents are presented, although large scaling corrections are present in the reachable lattice sizes., DGA, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2008 IAEA, Vienna. The authors acknowledge partial financial support from MEC (Spain), through research contract FIS2006-08533-C03, European Commission through contracts EGEE-II-031688 and int.eu.grid 031857 and from BSCH-UCM. J.L. Velasco is a DGA (Aragón, Spain) fellow., In TJ-II stellarator plasmas, in the electron cyclotron heating regime, an increase in the ion temperature is observed, synchronized with that of the electron temperature, during the transition to the core electron-root confinement (CERC) regime. This rise in ion temperature should be attributed to the joint action of the electron–ion energy transfer (which changes slightly during the CERC formation) and an enhancement of the ion confinement. This improvement must be related to the increase in the positive electric field in the core region. In this paper, we confirm this hypothesis by estimating the ion collisional transport in TJ-II under the physical conditions established before and after the transition to CERC. We calculate a large number of ion orbits in the guiding-centre approximation considering the collisions with a background plasma composed of electrons and ions. The ion temperature profile and the thermal flux are calculated in a self-consistent way, so that the change in the ion heat transport can be assessed., MEC (Spain), European Commission, BSCH-UCM, DGA (Aragón, Spain), Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2014 American Physical Society. Artículo firmado por 24 autores. The Janus project has been partially supported by the EU (FEDER funds, Grant No. UNZA05-33-003, MEC-DGA, Spain); by the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013, ERC Grant agreement N. 247328); by the MICINN (Spain) (Contracts No. FIS2006-08533, No. FIS2012-35719-C02, No. FIS2010-16587, and No. TEC2010-19207); by the SUMA project of INFN (Italy); by CAM (Spain); by the Junta de Extremadura (GR10158); by the Microsoft Prize 2007 and by the European Union (PIRSES-GA-2011-295302). F.R.-T. was supported by the Italian Research Ministry through the FIRB Project No. RBFR086NN1; M.B.-J. was supported by the FPU program (Ministerio de Educación, Spain); R.A.B. and J.M.-G. were supported by the FPI program (Diputación de Aragón, Spain); S.P.-G. was supported by the ARAID foundation; finally, J.M.G.-N. was supported by the FPI program (Ministerio de Ciencia e Innovación, Spain)., 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 field-programmable gate array (FPGAs), we have been able to reach times equivalent to 0.01 s 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., Unión Europea. FP7, EU (FEDER funds), Ministerio de Ciencia e Innovación (MICINN), INFN (Italy), CAM (Spain), Junta de Extremadura, Microsoft Prize 2007, European Union, Italian Research Ministry, Ministerio de Educación (Spain) under FPU program, Diputación de Aragón (Spain) under FPI program, ARAID foundation, Ministerio de Ciencia e Innovación (Spain) under FPI program, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2009 The American Physical Society. Artículo firmado por 20 autores. JANUS has been funded by European Union FEDER funds, Diputación General de Aragón Spain, Microsoft–Italy, and Eurotech. We were partially supported by MEC Spain through Contracts No. TEC2007-64188, No. FIS2006-08533, No. FIS2007-60977, and No. FIS2008- 01323, from CAM Spain under Contract No. CCG07- UCM/ESP-2532, and from the Microsoft Prize 2007. D.S. acknowledges Contract No. BFM2003-08532-C03-01 from MEC Spain. The authors would like to thank the Arénaire team, especially Jérémie Detrey and Florent de Dinechin for the VHDL code of the logarithm function., We perform numerical simulations, including parallel tempering, a four-state Potts glass model with binary random quenched couplings using the JANUS application-oriented computer. We find and characterize a glassy transition, estimating the critical temperature and the value of the critical exponents. Nevertheless, the extrapolation to infinite volume is hampered by strong scaling corrections. We show that there is no ferromagnetic transition in a large temperature range around the glassy critical temperature. We also compare our results with those obtained recently on the “random permutation” Potts glass., Comunidad de Madrid, European Union FEDER funds, Diputación General de Aragón Spain, Microsoft–Italy, Eurotech, MEC, Spain, Microsoft Prize 2007, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© EPLA, 2013. We are indebted with the Janus Collaboration for allowing us to analyze their thermalized configurations. We thank particularly David Yllanes for discussions and for assistance in the data analysis. We acknowledge support from MINECO, Spain, through research contracts FIS2012-35719-C02 and from the European Research Council (ERC) through grant agreement No. 247328. BS was supported by the FPU program (MECD, Spain)., Temperature chaos has often been reported in the literature as a rare-event–driven phenomenon. However, this fact has always been ignored in the data analysis, thus erasing the signal of the chaotic behavior (still rare in the sizes achieved) and leading to an overall picture of a weak and gradual phenomenon. On the contrary, our analysis relies on a largedeviations functional that allows to discuss the size dependences. In addition, we had at our disposal unprecedentedly large configurations equilibrated at low temperatures, thanks to the Janus computer. According to our results, when temperature chaos occurs its effects are strong and can be felt even at short distances., Unión Europea. FP7, Ministerio de Economía y Competitividad (MINECO), FPU program (MECD, Spain), Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

©2015 American Physical Society.We thank Enzo Marinari, Giorgio Parisi, and Andrea Maiorano for helping us with our first Pthreads programs. We also thank Andrea Pelissetto, Giorgio Parisi, and Matteo Lulli for discussing with us, prior to publication, their very interesting and accurate finite-time, finite-size scaling approach [62]. We thank as well Juan Jesus Ruiz-Lorenzo, Peter Young, and David Yllanes for discussions. The total simulation time devoted to this project was the equivalent of 36 days of the full (3072 AMD cores) Memento cluster (see http://bifi.es). We were partly supported by MINECO (Spain) through research Contract No. FIS2012-35719-C02., The statics-dynamics correspondence in spin glasses relate nonequilibrium results on large samples (the experimental realm) with equilibrium quantities computed on small systems (the typical arena for theoretical computations). Here we employ statics-dynamics equivalence to study the Ising spin-glass critical behavior in three dimensions. By means of Monte Carlo simulation, we follow the growth of the coherence length (the size of the glassy domains), on lattices too large to be thermalized. Thanks to the large coherence lengths we reach, we are able to obtain accurate results in excellent agreement with the best available equilibrium computations. To do so, we need to clarify the several physical meanings of the dynamic exponent close to the critical temperature., Ministerio de Economía y Competitividad (MINECO), España, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 1999 IOP Publishing Ltd. We acknowledge interesting discussions with D Stauffer and R Ziff. We thank CICyT (AEN97-1708 and AEN97-1693) for partial financial support. The computations have been carried out using the RTNN machines at Universidad de Zaragoza and Universidad Complutense de Madrid., Using Finite-Size Scaling techniques we obtain accurate results for critical quantities of the Ising model and the site percolation, in three dimensions. We pay special attention in parameterizing the corrections-to-scaling, what is necessary to put the systematic errors below the statistical ones., CICyT, Spain, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© Nature Publishing Group. We thank Luis Antonio Fernández and David Yllanes for providing us with their analysis program for the PT correlation function. We also thank Marco Baity-Jesi for helping us to prepare the figures. We are indebted to Mohammad Amin, Luis Antonio Fernández, Enzo Marinari, Denis Navarro, Giorgio Parisi, Federico Ricci-Tersenghi and Juan Jesús Ruiz-Lorenzo for discussions. We thank Luis Antonio Fernández, Daniel Lidar, Felipe LLanes-Estrada, David Yllanes and Peter Young for their reading of a preliminary version of the manuscript. We thank D-Wave Systems Inc. for granting us access to the chip. We acknowledge the use of algorithms and source code for a classic solver, devised and written by Alex Selby, available for public usage at https://github.com/alex1770/QUBO-Chimera. Our simulated annealing runs were carried out on the Picasso supercomputer. The authors thankfully acknowledge the computer resources, technical expertise and assistance provided by the staff at the Red Española de Supercomputación. IH acknowledges support by ARO grant number W911NF-12-1-0523. VMM was supported by MINECO (Spain) through research contract No FIS2012-35719-C02., Recent advances in quantum technology have led to the development and manufacturing of experimental programmable quantum annealing optimizers that contain hundreds of quantum bits. These optimizers, commonly referred to as 'D-Wave' chips, promise to solve practical optimization problems potentially faster than conventional 'classical' computers. Attempts to quantify the quantum nature of these chips have been met with both excitement and skepticism but have also brought up numerous fundamental questions pertaining to the distinguishability of experimental quantum annealers from their classical thermal counterparts. Inspired by recent results in spinglass theory that recognize 'temperature chaos' as the underlying mechanism responsible for the computational intractability of hard optimization problems, we devise a general method to quantify the performance of quantum annealers on optimization problems suffering from varying degrees of temperature chaos: A superior performance of quantum annealers over classical algorithms on these may allude to the role that quantum effects play in providing speedup. We utilize our method to experimentally study the D-Wave Two chip on different temperature-chaotic problems and find, surprisingly, that its performance scales unfavorably as compared to several analogous classical algorithms. We detect, quantify and discuss several purely classical effects that possibly mask the quantum behavior of the chip., Army Research Office, EE.UU., United States Goverment, Ministerio de Economía y Competitividad (MINECO), España, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2008 Elsevier B.V. We were partially supported by MEC (Spain) through contract No. FIS-2006-08533-C03-01 and by CAM (Spain) through contract No. CCG07-UCM/ESP-2532., We present Tethered Monte Carlo, a simple, general purpose method of computing the effective potential of the order parameter (Helmholtz free energy). This formalism is based on a new statistical ensemble, closely related to the micromagnetic one, but with an extended configuration space (through Creutz-like demons). Canonical averages for arbitrary values of the external magnetic field are computed without additional simulations. The method is put to work in the two-dimensional Ising model, where the existence of exact results enables us to perform high precision checks. A rather peculiar feature of our implementation, which employs a local Metropolis algorithm, is the total absence, within errors, of critical slowing down for magnetic observables. Indeed, high accuracy results are presented for lattices as large as L = 1024., MEC (Spain), CAM (Spain), Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2009, IEEE. Artículo firmado por 23 autores. We thank M. Lena and S. Sialino for their outstanding support during the commissioning of the first JANUS system., This paper describes JANUS, a modular massively parallel and reconfigurable FPGA-based computing system. Each JANUS module has a computational core and a host. The computational core is a 4x4 array of FPGA-based processing elements with nearest-neighbor data links. Processors are also directly connected to an I/O node attached to the JANUS host, a conventional PC. JANUS is tailored for, but not limited to, the requirements of a class of hard scientific applications characterized by regular code structure, unconventional data manipulation instructions and not too large data-base size. We discuss the architecture of this configurable machine, and focus on its use on Monte Carlo simulations of statistical mechanics. On this class of application JANUS achieves impressive performances: in some cases one JANUS processing element outperfoms high-end PCs by a factor ≈1000. We also discuss the role of JANUS on other classes of scientific applications., Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

@ 1997 Published by Elsevier Science B.V. We thank the CICyT (contracts AEN94-0218, AEN96-1634) for partial financial support, specially for the financing of dedicated Pentium Pro machines where most of the simulations have been done. J.J.R.L. is supported by an EC HMC (ERBFMBICT950429) grant., Using finite-size scaling methods we measure the thermal and magnetic exponents of the site percolation in four dimensions, obtaining a value for the anomalous dimension very different from the results found in the literature. We also obtain the leading corrections-to-scaling exponent and, with great accuracy, the critical density., CICyT, Spain, EC HMC, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2000 The American Physical Society. We gratefully acknowledge discussions with D. Belanger, J. Cardy and H. Rieger. We are grateful for partial financial support from CICyT (AEN97-1708 and AEN97-1693). The computations have been carried out using the RTNN machines (Universidad de Zaragoza and Universidad Complutense de Madrid) and the ORIGIN2000 at the Centro de Supercomputación Complutense (CSC)., We have studied numerically the effect of quenched site dilution on a weak first-order phase transition in three dimensions. We have simulated the site diluted three-states Potts model studying in detail the secondorder region of its phase diagram. We have found that the n exponent is compatible with the one of the three-dimensional diluted Ising model, whereas the h exponent is definitely different., CICyT, Spain, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

©2016 American Physical Society. We thank Ehsan Khatami for useful comments and suggestions. This work was partially supported by MINECO (Spain) through Grants No. FIS2012-35719-C02, No. FIS2015-65078-C2-1-P. Computation for the work described in this paper was partially supported by the University of Southern California's Center for High-Performance Computing (http://hpcc.usc.edu)., Recent technological developments in the field of experimental quantum annealing have made prototypical annealing optimizers with hundreds of qubits commercially available. The experimental demonstration of a quantum speedup for optimization problems has since then become a coveted, albeit elusive goal. Recent studies have shown that the so far inconclusive results, regarding a quantum enhancement, may have been partly due to the benchmark problems used being unsuitable. In particular, these problems had inherently too simple a structure, allowing for both traditional resources and quantum annealers to solve them with no special efforts. The need therefore has arisen for the generation of harder benchmarks which would hopefully possess the discriminative power to separate classical scaling of performance with size from quantum. We introduce here a practical technique for the engineering of extremely hard spin-glass Ising-type problem instances that does not require "cherry picking" from large ensembles of randomly generated instances. We accomplish this by treating the generation of hard optimization problems itself as an optimization problem, for which we offer a heuristic algorithm that solves it. We demonstrate the genuine thermal hardness of our generated instances by examining them thermodynamically and analyzing their energy landscapes, as well as by testing the performance of various state-of-the-art algorithms on them. We argue that a proper characterization of the generated instances offers a practical, efficient way to properly benchmark experimental quantum annealers, as well as any other optimization algorithm., Ministerio de Economía y Competitividad (MINECO), Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 1997 The American Physical Society. We thank J. L. Alonso and J. J. Ruiz-Lorenzo for many enlightening discussions. This work was partially supported by CICyT AEN93-0604, AEN94-0218, and AEN95-1284-E., We study the antiferromagnetic RP^(2) model in four dimensions. We find a second order transition with two order parameters, one ferromagnetic and the other antiferromagnetic. The antiferromagnetic sector has mean- field critical exponents and a renormalized coupling which goes to zero in the continuum limit. The exponents of the ferromagnetic channel are not the mean-field ones, but the difference can be interpreted as logarithmic corrections. We perform a detailed analysis of these corrections and conclude the triviality of the continuum limit of this model., CICyT, Spain, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2016 IEEE. Artículo firmado por 20 autores. We wish to thank Piero Vicini, Alessandro Lonardo, Davide Rossetti and Sergio De Luca for very useful discussions. We also thank Liliana Arrachea, Pierpaolo Bruscolini, Kenneth Dawson, Giacomo Marchiori, Yamir Moreno Vega, Giorgio Parisi, Ilenia Pedron and Federico Ricci-Tersenghi for sharing with us interesting ideas. This work has been partially supported by DGA, MEC (BFM2003-C08532-C03, FIS04-5073-C04, FISES2004-01399, FPA04-2602) and the European Community’s Human Potential Programme, contracts HPRNCT-2002-00307 (DYGLAGEMEM) and HPRN-CT-2002-00319 (STIPCO)., Dedicated machines designed for specific computational algorithms can outperform conventional computers by several orders of magnitude. In this note we describe Ianus, a new generation FPGA based machine and its basic features: hardware integration and wide reprogrammability. Our goal is to build a machine that can fully exploit the performance potential of new generation FPGA devices. We also plan a software platform which simplifies its programming, in order to extend its intended range of application to a wide class of interesting and computationally demanding problems. The decision to develop a dedicated processor is a complex one, involving careful assessment of its performance lead, during its expected lifetime, over traditional computers, taking into account their performance increase, as predicted by Moore’s law. We discuss this point in detail., DGA, MEC (Spain), European Community’s Human Potential Programme, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2010 IOP Publishing Ltd and SISSA. Artículo firmado por 21 autores. We acknowledge support from MICINN, Spain, through research contracts No. TEC2007- 64188, FIS2006-08533-C03, FIS2007-60977, FIS2009-12648-C03 and from UCM-Banco de Santander. BS and DY are FPU fellows (Spain) and RAB and JM-G are DGA fellows. SPG was supported by FECYT (Spain). The authors would like to thank the Arénaire team, especially J Detrey and F de Dinechin for the VHDL code of the logarithm function [76]. M Moore posed interesting questions that helped us sharpen the discussion in section 4.3., We present a massive equilibrium simulation of the three-dimensional Ising spin glass at low temperatures. The Janus special-purpose computer has allowed us to equilibrate, using parallel tempering, L = 32 lattices down to T ≈ 0.64Tc. We demonstrate the relevance of equilibrium finite-size simulations to understand experimental non-equilibrium spin glasses in the thermodynamical limit by establishing a time-length dictionary. We conclude that non-equilibrium experiments performed on a time scale of one hour can be matched with equilibrium results on L ≈ 110 lattices. A detailed investigation of the probability distribution functions of the spin and link overlap, as well as of their correlation functions, shows that Replica Symmetry Breaking is the appropriate theoretical framework for the physically relevant length scales. Besides, we improve over existing methodologies to ensure equilibration in parallel tempering simulations., Ministerio de Ciencia e Innovación (MICINN), UCM-Banco de Santander, FPU fellows (Spain), DGA fellows, FECYT (Spain), Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2014 IOP Publishing Ltd and SISSA Medialab srl. Artículo firmado por 24 autores. The Janus project has been partially supported by the EU (FEDER funds, No. UNZA05-33-003, MEC DGA, Spain), by the European Research Council under the European Union's Seventh Framework Programme (FP7/2007–2013, ERC grant agreement No. 247328), by MINECO (Spain) (contracts FIS2012-35719-C02, FIS2010-16587, TEC2010-19207), by the SUMA project of INFN (Italy), by the Junta de Extremadura (GR10158) and by the European Union (PIRSES-GA 2011-295302). FR-T was supported by the Italian Research Ministry through the FIRB project No. RBFR086NN1, MB-J was supported by the FPU programme (Ministerio de Educación, Spain), RAB and JM-G were supported by the FPI programme (Diputación de Aragón, Spain) and SP-G was supported by the ARAID foundation; finally JMG-N was supported by the FPI programme (Ministerio de Economía, Spain)., We perform equilibrium parallel-tempering simulations of the 3D Ising Edwards-Anderson spin glass in a field, using the Janus computer. A traditional analysis shows no signs of a phase transition. Yet, we encounter dramatic fluctuations in the behaviour of the model: Averages over all the data only describe the behaviour of a small fraction of it. Therefore we develop a new approach to study the equilibrium behaviour of the system, by classifying the measurements as a function of a conditioning variate. We propose a finite-size scaling analysis based on the probability distribution function of the conditioning variate, which may accelerate the convergence to the thermodynamic limit. In this way, we find a non-trivial spectrum of behaviours, where a part of the measurements behaves as the average, while the majority of them shows signs of scale invariance. As a result, we can estimate the temperature interval where the phase transition in a field ought to lie, if it exists. Although this would be critical regime is unreachable with present resources, the numerical challenge is finally well posed., Unión Europea. FP7, EU (FEDER funds Spain), Ministerio de Economía y Competitividad (MINECO), INFN (Italy), Junta de Extremadura (Spain), European Union, Italian Research Ministry, FPU programme (Ministerio de Educación, Spain), FPI programme (Diputación de Aragón, Spain), ARAID foundation, FPI programme (Ministerio de Economía, Spain), Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2007 The American Physical Society. We thank V. Erokhin and F. Zamponi for discussions. We were supported by MEC (Spain), through Contracts No. BFM2003-08532, No. FIS2004-05073, No. FPA2004- 02602, CAM (CAM-910383), and by BSCH—UCM. The CPU time utilized (at BIFI and CINECA) amounts to 10 years of 3 GHz PentiumIV, The phase diagram of soft spheres with size dispersion is studied by means of an optimized Monte Carlo algorithm which allows us to equilibrate below the kinetic glass transition for all size distributions. The system ubiquitously undergoes a first-order freezing transition. While for a small size dispersion the frozen phase has a crystalline structure, large density inhomogeneities appear in the highly disperse systems. Studying the interplay between the equilibrium phase diagram and the kinetic glass transition, we argue that the experimentally found terminal polydispersity of colloids is a purely kinetic phenomenon., MEC (Spain), CAM (Spain), BSCH-UCM (Spain), Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2003 American Physical Society. We are thankful to J. Blasco, J.M.D. Coey, J.M. de Teresa, J. Fontcuberta, M. García-Hernández, M.R. Ibarra, J. L. Martínez, L. Morellón, D. D. Sarma, and D. Serrate, M. Venkatesan, and especially to V. Laliena, for helpful discussions. V.M.M. was supported by E.C. Contract No. HPMF-CT- 2000-00450 and by a Ramón y Cajal contract (Spain). Financial support from Grants No. PB96-0875, FPA2000-0956, FPA2000-1252, FPA2001-1813 (MCyT, Spain), and 07N/ 0045/98 (C. Madrid) are acknowledged., The phase diagram of the double perovskites of the type Sr_(2-x)La_(x)FeMoO_(6) is analyzed, with and without disorder due to antisites. In addition to an homogeneous half metallic ferrimagnetic phase in the absence of doping and disorder, we find antiferromagnetic phases at large dopings, and other ferrimagnetic phases with lower saturation magnetization, in the presence of disorder., MCyT, Spain, C. Madrid, Spain, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

©2022 American Physical Society The authors wish to thank the Janus Collaboration for allowing us to analyze their data. We would like also to thank E. Marinari for interesting discussions. The analysis of the Janus configurations was performed at the ICCAEx Supercomputer Center in Badajoz, and we thank its staff for their assistance. This work was supported by the European Research Council under the European Unions Horizon 2020 Research and Innovation Programme (Grant No. 694925, G.P.), by Ministerio de Economía y Competitividad, Agencia Estatal de Investigación, and Fondo Europeo de Desarrollo Regional(FEDER)(Spain and European Union) through Grants No. PID2020-112936GB-I00 and No. PGC2018-094684-B-C21, and by Junta de Extremadura (Spain) through Grants No. GRU18079 and No. IB20079 (partially funded by FEDER). I.G.A.P. was supported by MCIU (Spain) through FPU Grant No. FPU18/02665., A growing body of evidence indicates that the sluggish low-temperature dynamics of glass formers (e.g., supercooled liquids, colloids, or spin glasses) is due to a growing correlation length. Which is the effective field theory that describes these correlations? The natural field theory was drastically simplified by Bray and Roberts in 1980. More than 40 years later, we confirm the tenets of Bray and Roberts’s theory by studying the Ising spin glass in an externally applied magnetic field, both in four spatial dimensions (data obtained from the Janus collaboration) and on the Bethe lattice., Unión Europea. Horizonte 2020, Ministerio de Economia, Industria y Competitividad (MINECO)/FEDER, Ministerio de Ciencia e Innovación (MICINN), Junta de Extremadura /FEDER, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

During my Ph.D., we made small progress in the secular question on the nature of the spin-glass system. However, we demonstrated the unique and powerful combination of experiments, theory, and simulations addressing complex dynamics. On one hand, the experimental progress on the sample preparation and the increased precision on the measurements of key physical observables have opened new prospects in the spinglass investigation. On the other hand, the Janus II special-purpose supercomputer, in combination with theory, is suficient to extend simulation time and length scales tovalues explored experimentally. The text is organized into four parts. In the following paragraphs, we introduce briefly each of them..., Esta tesis presenta nuestra modesta contribución a la comprensión y modelización de los vidrios de espín. En particular, hemos mostrado que la combinación resultados teóricos, numéricos y experimentales permite revolucionar la comprensión de la dinámica de estos sistemas complejos. Desde el punto de vista experimental, los progresos en la preparación de muestras se alían con la alta precisión de las medidas para abrir nuevas perspectivas previamente insospechadas. Por otro lado, el uso combinado del superordenador Janus II y el análisis teórico ha permitido obtener (e interpretar)simulaciones en una escala temporal comparable a la de los experimentos. Para explicar de manera coherente estos avances, hemos dividido el texto en cuatro partes cuyo contenido describimos a continuación...

© 2021 EPLA. We are grateful to Itay Hen for the helpful discussions. This work was supported by MINECO (Spain) through Grant No. PGC2018-094684-B-C21 (partially funded by FEDER) and the European Research Council under the European Union’s Horizon 2020 research and innovation program (Grant No. 694925-Lotglassy). This research used resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725., A recent 3-XORSAT challenge required to minimize a very complex and rough energy function, typical of glassy models with a random first-order transition and a golf-course-like energy landscape. We present the ideas beyond the quasi-greedy algorithm and its very efficient implementation on GPUs that are allowing us to rank first in such a competition. We suggest a better protocol to compare algorithmic performances and we also provide analytical predictions about the exponential growth of the times to find the solution in terms of free-energy barriers. Copyright (C) 2021 EPLA, Unión Europea. Horizonte 2020, Ministerio de Economía y Competitividad (MINECO)/FEDER, United States Department of Energy (DOE), Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© The Author(s) 2021 Artículo publicado por más de 10 autores. We are grateful for discussions with R. Orbach and Q. Zhai. This work was partially supported by Ministerio de Economia, Industria y Competitividad (MINECO, Spain), Agencia Estatal de Investigacion (AEI, Spain), and Fondo Europeo de Desarrollo Regional (FEDER, EU) through Grants No. FIS2016-76359-P, No. PID2019-103939RB-I00, No. PGC2018-094684-B-C21 and PGC2018-094684-B-C22, by the Junta de Extremadura (Spain) and Fondo Europeo de Desarrollo Regional (FEDER, EU) through Grant No. GRU18079 and IB15013 and by the DGA-FSE (Diputacion General de Aragon - Fondo Social Europeo). This project has also received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant No. 694925-LotglasSy). DY was supported by the Chan Zuckerberg Biohub and IGAP was supported by the Ministerio de Ciencia, Innovacion y Universidades (MCIU, Spain) through FPU grant no. FPU18/02665. BS was supported by the Comunidad de Madrid and the Complutense University of Madrid (Spain) through the Atraccion de Talento program (Ref. 2019-T1/TIC-12776)., Experiments featuring non-equilibrium glassy dynamics under temperature changes still await interpretation. There is a widespread feeling that temperature chaos (an extreme sensitivity of the glass to temperature changes) should play a major role but, up to now, this phenomenon has been investigated solely under equilibrium conditions. In fact, the very existence of a chaotic effect in the non-equilibrium dynamics is yet to be established. In this article, we tackle this problem through a large simulation of the 3D Edwards-Anderson model, carried out on the Janus II supercomputer. We find a dynamic effect that closely parallels equilibrium temperature chaos. This dynamic temperature-chaos effect is spatially heterogeneous to a large degree and turns out to be controlled by the spin-glass coherence length xi. Indeed, an emerging length-scale xi* rules the crossover from weak (at xi MUCH LESS-THAN xi*) to strong chaos (xi >> xi*). Extrapolations of xi* to relevant experimental conditions are provided. While temperature chaos is an equilibrium notion that denotes the extreme fragility of the glassy phase with respect to temperature changes, it remains unclear whether it is present in non-equilibrium dynamics. Here the authors use the Janus II supercomputer to prove the existence of dynamic temperature chaos, a nonequilibrium phenomenon that closely mimics equilibrium temperature chaos., Unión Europea. Horizonte 2020, Ministerio de Economia, Industria y Competitividad (MINECO)/FEDER, Ministerio de Ciencia e Innovación (MICCIN), Comunidad de Madrid/Universidad Complutense de Madrid, Junta de Extremadura /FEDER, Chan Zuckerberg Biohub, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© the author(s) This work was partially supported by Ministerio de Economía, Industria y Competitividad (MINECO, Spain), Agencia Estatal de Investigación (AEI, Spain), and Fondo Europeo de Desarrollo Regional (FEDER, EU) through Grants No. PGC2018-094684-B-C21, No. FIS2017-84440-C2-2-P, and No. MTM2017-84446-C2-2-R. A.L. and J.S. were also partially supported by Grant No. PID2020-116567GB-C22 AEI/10.13039/501100011033. A.L. was also partly supported by Grant No A-FQM-644-UGR20 Programa operativo FEDER Andalucía 2014–2020. J.S. was also partly supported by the Madrid Government (Comunidad de Madrid-Spain) under the Multiannual Agreement with UC3M in the line of Excellence of University Professors (EPUC3M23), and in the context of the V PRICIT (Regional Programme of Research and Technological Innovation). I.G.-A.P. was supported by the Ministerio de Ciencia, Innovación y Universidades (MCIU, Spain) through FPU Grant No. FPU18/02665., Cooling and heating faster a system is a crucial problem in science, technology, and industry. Indeed, choosing the best thermal protocol to reach a desired temperature or energy is nota trivial task. Noticeably, we find that the phase transitions may speed up thermalization in systems where there are no conserved quantities. In particular, we show that the slow growth of magnetic domains shortens the overall time that the system takes to reach a final desired state. To prove that statement, we use intensive numerical simulations of a prototypical many-body system, namely, the two-dimensional Ising model., Ministerio de Economía, Industria y Competitividad (MINECO)/FEDER, Ministerio de Economía, Industria y Competitividad (MINECO)/AEI, Ministerio de Ciencia e Innovación (MICCIN), Junta de Andalucía/FEDER, Comunidad de Madrid/Universidad Carlos III de Madrid, Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

© 2021 IOP Publishing Ltd We are grateful for helpful discussions with S Swinnea about sample characterisation. This work was partially supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering, under Award No. DE-SC0013599, and Contract No. DE-AC02-07CH11358. We were partly funded as well by Ministerio de Economia, Industria y Competitividad (MINECO, Spain), Agencia Estatal de Investigacion (AEI, Spain), and Fondo Europeo de Desarrollo Regional (FEDER, EU) through Grants No. FIS2016-76359-P, No. PID2019-103939RB-I00, No. PGC2018-094684-B-C21 and PGC2018-094684-B-C22, by the Junta de Extremadura (Spain) and Fondo Europeo de Desarrollo Regional (FEDER, EU) through Grant Nos. GRU18079 and IB15013 and by the DGA-FSE (Diputaci ' on General de Aragon-Fondo Social Europeo). This project has also received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant No. 694925 LotGlasSy). D Y was supported by the Chan Zuckerberg Biohub and IGAP was supported by the Ministerio de Ciencia, Innovacion y Universidades (MCIU, Spain) through FPU Grant No. FPU18/02665. B S was supported by the Comunidad de Madrid and the Complutense University of Madrid (Spain) through the Atraccion de Talento programme (reference 2019-T1/TIC-12776). The simulations of section 5.6.2 were carried out at the ICCAEx supercomputer centre in Badajoz. We thank the staff at ICCAEx for their assistance., The synergy between experiment, theory, and simulations enables a microscopic analysis of spin-glass dynamics in a magnetic field in the vicinity of and below the spin-glass transition temperature T-g. The spin-glass correlation length, xi(t, t(w); T), is analysed both in experiments and in simulations in terms of the waiting time t(w) after the spin glass has been cooled down to a stabilised measuring temperature T < T-g and of the time t after the magnetic field is changed. This correlation length is extracted experimentally for a CuMn 6 at. % single crystal, as well as for simulations on the Janus II special-purpose supercomputer, the latter with time and length scales comparable to experiment. The non-linear magnetic susceptibility is reported from experiment and simulations, using xi(t, t(w); T) as the scaling variable. Previous experiments are reanalysed, and disagreements about the nature of the Zeeman energy are resolved. The growth of the spin-glass magnetisation in zero-field magnetisation experiments, M-ZFC(t, t(w); T), is measured from simulations, verifying the scaling relationships in the dynamical or non-equilibrium regime. Our preliminary search for the de Almeida-Thouless line in D = 3 is discussed., Unión Europea. Horizonte 2020, Ministerio de Economia, Industria y Competitividad (MINECO)/AEI/FEDER, Ministerio de Ciencia e Innovación (MICCIN), Comunidad de Madrid/Universidad Complutense de Madrid, Junta de Extremadura /FEDER, United States Department of Energy (DOE), Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub

During my Ph.D., we made small progress in the secular question on the nature of the spin-glass system. However, we demonstrated the unique and powerful combination of experiments, theory, and simulations addressing complex dynamics. On one hand, the experimental progress on the sample preparation and the increased precision on the measurements of key physical observables have opened new prospects in the spinglass investigation. On the other hand, the Janus II special-purpose supercomputer, in combination with theory, is suficient to extend simulation time and length scales tovalues explored experimentally. The text is organized into four parts. In the following paragraphs, we introduce briefly each of them...

© 2020 American Physical Society. Artículo publicado por más de 10 autores. We are grateful for helpful discussions with S. Swinnea about sample characterization. This work was partially supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering, under Award No. DE-SC0013599, and Contract No. DE-AC02-07CH11358; by the Ministerio de Economia, Industria y Competitividad (MINECO, Spain), Agencia Estatal de Investigacion (AEI, Spain), and Fondo Europeo de Desarrollo Regional (FEDER, EU) through Grants No. FIS2016-76359-P, No. PID2019-103939RB-I00, No. PGC2018-094684-B-C21, and No. PGC2018-094684-B-C22; by the Junta de Extremadura (Spain) and Fondo Europeo de Desarrollo Regional (FEDER, EU) through Grants No. GRU18079 and No. IB15013. This project has also received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant No. 694925-LotglasSy). D. Y. was supported by the Chan Zuckerberg Biohub and I. G. A. P. was supported by the Ministerio de Ciencia, Innovacion y Universidades (MCIU, Spain) through FPU Grant No. FPU18/02665. B. S. was supported by the Comunidad de Madrid and the Complutense University of Madrid (Spain) through the Atraccion de Talento program (Ref. 2019-T1/TIC-12776)., The correlation length xi, a key quantity in glassy dynamics, can now be precisely measured for spin glasses both in experiments and in simulations. However, known analysis methods lead to discrepancies either for large external fields or close to the glass temperature. We solve this problem by introducing a scaling law that takes into account both the magnetic field and the time-dependent spin-glass correlation length. The scaling law is successfully tested against experimental measurements in a CuMn single crystal and against large-scale simulations on the Janus II dedicated computer., Unión Europea. Horizonte 2020, Ministerio de Economía y Competitividad (MINECO)/FEDER, Ministerio de Ciencia e Innovación (MICCIN), Comunidad de Madrid/Universidad Complutense de Madrid, Junta de Extremadura /FEDER, United States Department of Energy (DOE), Depto. de Física Teórica, Fac. de Ciencias Físicas, TRUE, pub