# XXIII National Conference on Statistical Physics and Complex Systems

## in collaboration with Scuola IMT Alti Studi Lucca and with the French Embassy in Italy

June 20th - 22nd 2018
Conference Center - Aule delle Scienze, University of Parma - Campus

## Dear friends,

The XXIII National Conference on Statistical Physics and Complex Systems will be held from June 20th to June 22nd 2018 at the Conference Center - Aule delle Scienze Building in the University Campus of Parma.

This year the conference will be organized in collaboration with Scuola IMT Alti Studi Lucca and it will be an opportunity for PhD students and young researchers in Statistical Physics to show their works, during a dedicated session.

In particular, on June 21st, the session ”Recent developments in theoretical neuroscience: temporal networks and response to noise” will be organized in collaboration with the French Embassy in Italy (Bando Cassini 2017), to encourage collaboration between young Italian and French researchers. We welcome oral and poster contributions from the participants as well as contributions to the special session dedicated to young researchers.

There is no registration fee, but for organization purposes we kindly ask you to send as soon as possible an e-mail to stat@fis.unipr.it with the registration form, shown on this conference website.
In case you are interested in presenting a contribution, please fill the second part of the registration form and submit it to stat@fis.unipr.it before May 31st 2018. For further information about the conference and the city of Parma, please contact stat@fis.unipr.it

We look forward to meeting you in Parma!

## Organization

### Scientific Committee

• Raffaella Burioni - Università di Parma
• Guido Caldarelli - Scuola IMT Alti Studi Lucca
• Davide Cassi - Università di Parma
• Roberto Livi - Università di Firenze

### Organizing Committee

• Elena Bertolotti - Università di Parma
• Alessandro Vezzani - CNR-IMEM Parma
• Sandro Wimberger - Università di Parma

### Young researchers day

• Giulio Cimini - Scuola IMT Alti Studi Lucca

### Scientific Secretariat

• Victor Buendia Ruiz-Azuaga - Università di Parma e Universidad de Granada
• Michele Tizzani - Università di Parma

## Registration

There is no registration fee, but for organization purposes we kindly ask you to register May, 31st 2018 .
Send an e-mail to stat@fis.unipr.it including the informations required in the form below.
Please do not send us your registration form in pdf, doc, docx, rtf, html format. Just insert the required information in the body of the email, in plain text. Latex formulas are allowed in the title and abstract of your presentation.

REGISTRATION FORM
First name:
Surname:
E-mail:
Affiliation:
I will participate in the social dinner, on Thursday, June 21th 2018: yes [ ] no [ ]
I'd like to contribute an oral/poster presentation
oral [ ] young researchers session [ ] poster [ ]
Title:
Abstract:


## Participants

2.Amato GiulioFreiburg Universitygiulio.amato@physik.uni-freiburg.de
3.Artuso RobertoINFN - Milanoroberto.artuso@uninsubria.it
5.Baldovin MarcoUniversità di Roma la Sapienzabaldovin.m@gmail.com
6.Bertolotti ElenaUniversità di Parmaelena.bertolotti1@fis.unipr.it
7.Bi HongjieUniversité de Cergy-Pontoise - Francehongjiebi@gmail.com
9.Bonini LucaUniversità di Parmaluca.bonini@unipr.it
10.Borgonovi FaustoUniversità Cattolica di Bresciafausto.borgonovi@unicatt.it
11.Budinich MarcoUniversità di Trieste & INFNmbh@ts.infn.it
13.Burioni RaffaellaUniversità di Parmaraffaella.burioni@fis.unipr.it
14.Caldarelli GuidoScuola IMT Alti Studi Luccaguido.caldarelli@imtlucca.it
15.Caprini LorenzoGran Sasso Science Institutelorenzo.caprini@gssi.it
16.Casartelli MarioUniversità di Parmamario.casartelli@fis.unipr.it
17.Caselle MicheleUniversità di Torinocaselle@to.infn.it
19.Cescatti FabianaUniversità di Parmafabiana.cescatti@studenti.unipr.it
20.Cicuta GiovanniUniversità di Parmagiovanni.cicuta@fis.unipr.it
21.Cimini GiulioScuola IMT Alti Studi Luccagiulio.cimini@imtlucca.it
22.Clawson WesleyINS - Aix-Marseille University wesley.p.clawson@gmail.com
23.Codello AlessandroSISSA - Triestecodello@sissa.it
24.Colcelli AndreaSISSA Triesteacolcelli@sissa.it
25.Colombo AlessandroUniversità degli Studi di Milanoalessandro.colombo6@unimi.it
26.Corberi FedericoUniversità degli Studi di Salernocorberi@sa.infn.it
27.Crisanti AndreaUniversità di Roma la Sapienzaandrea.crisanti@phys.uniroma1.it
29.Dall'Asta LucaPolitecnico di Torinoluca.dallasta@polito.it
30.De Domenico ManlioFondazione Bruno Kesslermdedomenico@fbk.eu
31.De Santis FrancescoUniversità di Roma la Sapienzafrancesco.desantis@roma1.infn.it
32.Di Cintio PierfrancescoCNR-IFAC & INFN - Firenzepdicintio@gmail.com
34.Di Volo MatteoUNIC CNRS Francem.divolo@hotmail.com
35.Emiliano MarcheseScuola IMT Alti Studi Lucca
37.Filiberti ZenoUniversità dell'Insubriaz.filiberti@gmail.com
38.Fiorentino JonathanUniversità di Roma la Sapienzajonathan.fiorentino@uniroma1.it
39.Furlan MattiaUniversità di Torinomattia.furlan@to.infn.it
40.Gabrielli AndreaCNR-ISC Romaandrea.gabrielli@roma1.infn.it
41.Galli Davide EmilioUniversità degli Studi di MilanoDavide.Galli@unimi.it
42.Ghavasieh ArshamFondazione Bruno Kesslerarsham.ghavasieh@yahoo.com
43.Gherardi MarcoUniversità di Milanomarco.gherardi@unimi.it
44.Giorda PaoloUniversità di Paviamagpaolo16@gmail.com
45.Giuliano RosaUniversità della Calabriarosa.giuliano@unical.it
47.Köksal Ersöz ElifINRIA Sophia Antipolis - Méditerranéelif.koksal@inria.fr
48.Kropf ChahanINFN - Paviachahan.kropf@pv.infn.it
49.Leuzzi LucaCNR-NANOTECluca.leuzzi@cnr.it
50.Livi RobertoUniversità di Firenzelivi@fi.infn.it
51.Mambretti FrancescoUniversità degli Studi di Milanofrancesco.mambretti@unimi.it
52.Mancastroppa MarcoUniversità di Parmamarco.mancastroppa@studenti.unipr.it
53.Mannella RiccardoUniversità di Pisariccardo.mannella@unipi.it
54.Marinari EnzoUniversità di Roma la Sapienzaenzo.marinari@roma1.infn.it
55.Mastrandrea RossanaScuola IMT Alti Studi Luccarossmastrandrea@gmail.com
56.Matteo SerafinoScuola IMT Alti Studi Lucca
57.Mazzolini AndreaICTP Triesteandrea.mazzolini.90@gmail.com
58.Mirko HuScuola IMT Alti Studi Lucca
59.Molinelli SimoneUniversità di Milano
62.Nghiem Trang-AnhEuropean Institute of Theoretical Neuroscience - Paristranganh.nghiem@gmail.com
63.Onofri ManueleUniversità dell'Insubriam.onofri@hotmail.com
64.Osella MatteoUniversità di Torinomosella@to.infn.it
65.Paris MatteoUniversità di Milanomatteo.paris@unimi.it
66.Petiziol FrancescoUniversità di Parmafrancesco.petiziol@studenti.unipr.it
67.Petri AlbertoCNR-ISC Romaalberto.petri@isc.cnr.it
68.Polettini MatteoUniversity of Luxembourgmatteo.polettini@uni.lu
69.Preto LucreziaUniversità di Parmalucrezia.preto@studenti.unipr.it
70.Pretti MarcoISC Torino
72.Rapisardi GiacomoScuola IMT Alti Studi Luccagiacomo.rapi@gmail.com
73.Rosay SophieICTP - Triestesophie.rosay@gmail.com
74.Roy AnjanICTP - Triesteanjanroyal@gmail.com
75.Ruffo StefanoSISSA - Triesteruffo@sissa.it
77.Sireci MatteoLMU - Munichmatteo.sireci@physik.uni-muenchen.de
78.Squartini TizianoScuola IMT Alti Studi Luccatiziano.squartini@imtlucca.it
79.Stucchi MarcoUniversità di Parmamarco.stucchi@studenti.unipr.it
81.Tizzani MicheleUniversità di Parmamichele.tizzani@studenti.unipr.it
82.Torta PietroUniversità degli Studi di Milanopietro.93@icloud.com
83.Trasarti Battistoni Robertorobtb2005@libero.it
84.Vezzani AlessandroCNR-IMEM Parmaalessandro.vezzani@fis.unipr.it
86.Wagner AlexanderRuprecht-Karls Universität - Heidelbergalexander.wagner@stud.uni-heidelberg.de
87.Wimberger SandroUniversità di Parmasandromarcel.wimberger@unipr.it
88.Zamparo MarcoPolitectico di Torinomarco.zamparo@polito.it

## Program

### Friday, June 22nd 2018 - young reasearchers day

 9:30 - 9:50 Andrea Mazzolini - ICTP, Trieste Zipf and Heaps laws from dependency structures in component systems Complex natural and technological systems can be considered, on a coarse-grained level, as assemblies of elementary components: for example, genomes as sets of genes, or texts as sets of words. On one hand, the joint occurrence of components emerges from architectural and specific constraints in such systems. On the other hand, general regularities may unify different systems, such as the broadly studied Zipf and Heaps laws, respectively concerning the distribution of component frequencies and their number as a function of system size. Dependency structures (i.e., directed networks encoding the dependency relations between the components in a system) were proposed recently as a possible organizing principles underlying some of the regularities observed. However, the consequences of this assumption were explored only in binary component systems, where solely the presence or absence of components is considered, and multiple copies of the same component are not allowed. Here, we consider a simple model that generates, from a given ensemble of dependency structures, a statistical ensemble of sets of components, allowing for components to appear with any multiplicity. Our model is a minimal extension that is memoryless, and therefore accessible to analytical calculations. A mean-field analytical approach (analogous to the "Zipfian ensemble" in the linguistics literature) captures the relevant laws describing the component statistics as we show by comparison with numerical computations. In particular, we recover a power-law Zipf rank plot, with a set of core components, and a Heaps law displaying three consecutive regimes (linear, sub-linear and saturating) that we characterize quantitatively. 9:50 - 10:10 Marco Baldovin - Sapienza Università di Roma Langevin equation in systems with also negative temperatures We discuss how to derive a Langevin equation (LE) in non standard systems, i.e. when the kinetic part of the Hamiltonian is not the usual quadratic function. This generalization allows to consider also cases with negative absolute temperature. We first give some phenomenological arguments suggesting the shape of the viscous drift, replacing the usual linear viscous damping, and its relation with the diffusion coefficient modulating the white noise term. As a second step, we implement a procedure to reconstruct the drift and the diffusion term of the LE from the time-series of the momentum of a heavy particle embedded in a large Hamiltonian system. Applying the method to systems with negative temperature, we can observe that also in this case there is a suitable LE, obtained with a precise protocol, able to reproduce in a proper way the statistical features of the slow variables. In other words, even in this context, systems with negative temperature do not show any pathology. 10:10 - 10:30 Mattia Radice - Università dell’Insubria A persistent random walk on an averaged environment for the Lévy-Lorentz gas Persistent random walks represent a class of stochastic models where, in their simplest version, a particle jumps to a nearest-neighbour site where there is a probability T of being transmitted and R of being reflected. Such nontrivial, correlated random walks have been recognized as a natural model for a number of relevant settings, from long-chain polymers, to chemotaxis, to active matter, but many of the associated statistical properties still remain unexplored. We introduce a non-homogeneous, persistent random walk that may be viewed as a mean-field version of the Lévy-Lorentz gas, which consists of an array of scatterers whose distances are distributed according to a Lévy distribution with parameter $0<\alpha<2$, i.e. a distribution whose second moment is not defined. Depending on the values of $\alpha$, the model shows a transition from normal transport ($1<\alpha<2$) to superdiffusion ($0<\alpha<1$), with an exponent $\nu(\alpha)=2/(1+\alpha)$, which is analytically derived by an appropriate continuum limit. Joint work with Roberto Artuso, Giampaolo Cristadoro and Manuele Onofri 10:30 - 10:50 Alessandro Colombo - Università degli Studi di Milano Miming the Memes for Imaging the Unimagined Coherent Diffractive Imaging (CDI) is a technique for imaging matter hit by coherent radiation. The experimentally recorded diffraction pattern $I_{i,j}$ is the square modulus of the Fourier Transform (FT) of the sample density distribution $\rho_{i,j}$, while any information about its phases is lost. Therefore, the inverse FT to get the real-space image of the sample can be accomplished only after the retrieval of the phase information by means of suitable algorithms. These algorithms treats each entry of $\rho_{i,j}$ as a free parameter, trying to optimize the discrepancy with the experimental measurement $I_{i,j}$. The number of unknowns involved in the optimization, which merely are the pixels of the image $\rho_{i,j}$, runs from $10^5$ for 2D CDI up to $10^7$ for the 3D case. This means that the solution is a point in a $10^{5 \sim 7}$-dimensional space. Standard deterministic algorithms for phase retrieval are iterative gradient-based approaches, which suffer from many limitations, among which stagnation in local optima. On the other side, purely stochastic approaches are doomed to fail, due to the high dimensionality of the optimization problem and the involvement of the Fourier Transform in the evaluation of the cost function. Our hybrid stochastic method, called Memetic Phase Retrieval (MPR) [1], mixes a genetic algorithm with gradient-based procedures, giving rise to a memetic algorithm, a class of stochastic optimization methods representing one of the recent growing areas of research in evolutionary computation. In particular, MPR treats a population of candidate solutions to the problem, which are able to self-improve via standard iterative approaches, and combines, step by step, their information by the use of computational intelligence. The complex dynamic of MPR is capable to approach and identify the solution much better than the standard procedures. Imaging results on 2D and 3D imaging will be presented, along with a description of the method, showing how much computational intelligence is effective in facing such a complex optimization problem. [1] Colombo, Alessandro, et al. "Facing the phase problem in coherent diffractive imaging via memetic algorithms." Scientific Reports 7 (2017): 42236. 10:50 - 11:20 coffee break 11:20 - 11:40 Marco Faccioli - Università di Padova Gaussian fluctuations in quantum phase transitions We discuss the effect of Gaussian quantum fluctuations close to the critical point of a quantum phase transition [1]. In particular, we analyze the effective action of the Bose-Hubbard Hamiltonian close to the Mott-superfluid phase transition [2]. This effective action contains the familiar Ginzburg-Landau-Wilson terms [3] but also first order and second order time derivatives of the complex order parameter. We investigate the elementary excitations of this effective action finding that they are in good agreement with experimental data [4]. From the elementary excitations and using dimensional regularization [5], we determine beyond-mean-field Gaussian corrections to the zero-temperature equation of state of the system. We show that these Gaussian corrections crucially depend on the dimensionality of the system. [1] S. Sachdev, Quantum Phase Transitions (Cambridge Univ. Press, 2012). [2] K. Sengupta and N. Dupuis, Phys. Rev. A 71, 033629 (2005). [3] D. Amit, Field Theory, the Renormalization Group and Critical Phenomena (World Scientific, 2005). [4] M. Endres et al., Nature 487, 454 (2012). [5] L. Salasnich and F. Toigo, Phys. Rep. 640, 1 (2016). 11:40 - 12:00 Francesco Mambretti - Università degli Studi di Milano Energy-landscape driven crystallization slowdown in supercooled liquid mixtures Crystallization is a process of fundamental importance in a variety of fields ranging from materials to climate science. At the microscopic level, crystallization in supercooled liquids is described qualitatively by the classical crystal nucleation and growth theories. In general, however, solid formation is a far more complex process and even the rich behavior observed in simple binary mixtures greatly challenges our current understanding of crystallization. Recently, I joined the group of R. Grisenti in an experimental campaign at DESY, Germany, based on innovative x-ray scattering measurements on liquid microjets [1]. The results have revealed a non-trivial dependence of the crystallization rate on the mixing ratio of supercooled Argon-Krypton liquid mixtures. Our Molecular Dynamics simulations show that this dependence is mainly related to an increased probability for fluctuations between crystal-like and liquid-like states at the crystal/liquid interface driven by the change in the potential energy landscape with composition. The emerging picture might be valid in general, providing a major step towards a more sophisticated theory of crystal growth in out-of-equilibrium supercooled liquids. Moreover, these results support the hypothesis[2] that the energy-landscape complexity may play a leading role also in systems characterized by a higher supercooling degree and by the competition between the crystal formation and the onset of a glassy phase. 1) R.E. Grisenti et al., Phys. Rev. Lett. 90, 234501 (2003) 2) P.G. Debenedetti et al., Nature 410, 259 (2001) 12:00 - 12:20 Chahan Kropf - INFN, Pavia Optimal exciton current in one-dimensional chains Finding optimal parameters for exciton transport in small quantum systems is an important step to guide the building of novel and efficient light-harvesting devices. In one-dimensional models of finite size attached to a lead (modeled to study exciton transport) coherence-enhanced transport is achieved when the coupling to the lead is close to the superradiant transition [1]. Using these results we show that such coherence-enhanced transport is compatible with the parameters of transition metal oxides thin films, and thus the latter can potentially be used for experimental verification. In addition, we benchmark our model with more realistic dynamical mean-field theory (DMFT) calculations of a Hubbard model in the Mott insulating phase in a parameter range close to the optimum. Our work suggests that coherence-enhanced transport is achievable in nano-scale solid state devices which would provide an experimental platform for research on light-harvesting devices with substantial advantages over their bio-molecule based counterparts. 1. G.L. Celardo, F. Borgonovi, M. Merkli, V.I. Tsifrinovich, and G.P. Berman, J. Phys. Chem. C, 116, 22105 (2012) 12:20 - 12:40 Rosa Giuliano - Università della Calabria Persistent current and zero-energy Majorana modes in a p-wave disordered superconducting ring In this talk will be discussed the emergence of zero-energy Majorana modes in a disordered finite-length p-wave one-dimensional superconducting ring, pierced by a magnetic flux Φ when it is tuned at an appropriate value Φ=Φ∗. In the absence of fermion parity conservation, will be evidenced the emergence of the Majorana modes by looking at the discontinuities in the persistent current I[Φ] at Φ=Φ∗. By monitoring the discontinuities in I[Φ], will be sho9wn how to map out the region in parameter space characterized by the emergence of Majorana modes in the disordered ring. 12:40 - 13:00 Andrea Colcelli - SISSA, Trieste Deviations from Off-Diagonal Long-Range Order and Mesoscopic Condensation in One-Dimensional Quantum Systems A quantum system exhibits off-diagonal long-range order (ODLRO) when the largest eigenvalue $\lambda_0$ of the one-body-density matrix scales as $\lambda_0 \sim N$, where $N$ is the total number of particles. Putting $\lambda_0 \sim N^{{\cal C}}$ to define the scaling exponent ${\cal C}$, then ${\cal C}=1$ corresponds to ODLRO and ${\cal C}=0$ to the single-particle occupation of the density matrix orbitals. When $0<{\cal C}<1$, ${\cal C}$ can be used to quantify deviations from ODLRO. In this talk I will present the study of the exponent ${\cal C}$ in a variety of one-dimensional bosonic and anyonic systems. 13:00 - 14:30 lunch break 14:30 - 14:50 Zeno Filiberti - Università degli studi dell'Insubria A statistical approach to thermo-osmosis P. Anzini Z. Filiberti and A. Parola Fluids in temperature gradients are among the simplest systems out of equilibrium and serve as testing ground for our understanding of stationary, non equilibrium states. A temperature gradient in the bulk drives a heat flux, while the local density changes and the pressure remain uniform, granting mechanical equilibrium. However, near a surface, the pressure balance cannot be realized and the fluid is set into motion. This phenomenon is known as thermo-osmosis and has been studied in rarefied gases since many years [1,2]. The same effect is also expected in liquids, although the lengthscales involved are much shorter. Arguments based on non equilibrium thermodynamics led Derjaguin to conclude that the phenomenon originates at the wall-fluid interface and an approximate expression for the thermo-osmotic velocity in liquids was proposed [3]. Only recently numerical simulations attempted a quantitative investigation of this effect, while a direct experimental evidence is still missing. Here, starting from a microscopic model of molecular fluid and taking advantage of the Kubo-Mori linear response theory, we provide a first principle description of the phenomenon. By specializing the resulting expressions to the liquid and to the gas regimes we show that two quite different physical mechanisms are at work: while in dense fluids the phenomenon originates from the anisotropies of the pressure tensor near the wall, in agreement with Derjaguin approach, in the rarefied limit the mechanism has a purely kinetic nature and the linear response formalism confirms the understanding based on kinetic theories. [1] F.H. Kennard, "Kinetic Theory of Gases" (McGraw Hill, 1938) [2] Y. Sone, Annu. Rev. Fluid Mech. 32, 779 (2000) [3] N.V. Churaev, B.V. Derjaguin, V.M. Muller, "Surface Forces" (Springer 1987) 14:50 - 15:10 Lorenzo Caprini - Gran Sasso Science Institute (GSSI) Activity induced delocalization and freezing in self-propelled systems We study a system of interacting active particles, propelled by colored noises, characterized by an activity time $\tau$, and confined by a single-well anharmonic potential. We observe that - already with negligible interactions - increasing $\tau$ pushes the particles far from the potential minimum, until a saturation distance is reached. We compute the phase diagram (activity vs interaction length), showing that interaction does not spoil this delocalisation phenomenon but induces a liquid- or solid-like structure in the densest regions. An approximate analytical scheme gives fair predictions for the density profiles in the weakly interacting case. The analysis of non-equilibrium heat fluxes of the system reveals that in the region of largest concentration of particles equilibrium is restored in several aspects. 15:10 - 15:30 Francesco De Santis - Sapienza Università di Roma Computation of the Zero Temperature RSB order parameter in Bethe Lattice Spin Glasses Bethe Lattice Spin Glasses are models with finite connectivity which undergo a Replica Symmetry Breaking (RSB) phase transition in field, at zero temperature. We compute numerically the RSB order parameter of the model near the transition, in the case of minimum connectivity (z=3) and bimodal distribution of the couplings (J=±1). The method is based on a universal formula which relates the order parameter to the joint probability distribution of the energy difference and overlap of excitations induced by a convenient perturbation to the Hamiltonian. 15:30 - 15:50 Giacomo Rapisardi - Scuola IMT Alti Studi Lucca Multiple structural transitions in interacting networks Many real-world systems can be modeled as interconnected multilayer networks, namely a set of networks interacting with each other. Here we present a perturbative approach to study the properties of a general class of interconnected networks as inter-network interactions are established. We reveal multiple structural transitions for the algebraic connectivity of such systems, between regimes in which each network layer keeps its independent identity or drives diffusive processes over the whole system, thus generalizing previous results reporting a single transition point. Furthermore we show that, at first order in perturbation theory, the growth of the algebraic connectivity of each layer depends only on the degree configuration of the interaction network (projected on the respective Fiedler vector), and not on the actual interaction topology. Our findings can have important implications in the design of robust interconnected networked system, particularly in the presence of network layers whose integrity is more crucial for the functioning of the entire system. We finally show results of perturbation theory applied to the adjacency matrix of the interconnected network, which can be useful to characterize percolation processes on such systems. 15:50 - 16:10 Jonathan Fiorentino - Sapienza Università di Roma Statistics of optimal information flow in ensembles of regulatory motifs Genetic regulatory circuits universally cope with different sources of noise that limit their ability to coordinate input and output signals. In many cases, optimal regulatory performance can be thought to correspond to configurations of variables and parameters that maximize the mutual information between inputs and outputs. Since the mid-2000s, such optima have been well characterized in several biologically relevant cases. Here we use methods of statistical field theory to calculate the statistics of the maximal mutual information (the “capacity”) achievable by tuning the input variable only in an ensemble of regulatory motifs, such that a single controller regulates N targets. Assuming (i) sufficiently large N, (ii) quenched random kinetic parameters, and (iii) small noise affecting the input-output channels, we can accurately reproduce numerical simulations both for the mean capacity and for the whole distribution. Our results provide insight into the inherent variability in effectiveness occurring in regulatory systems with heterogeneous kinetic parameters.

### Poster Session - Thursday

 Giulio Amato - Freiburg University Quantum transport with cold atoms The classical theory of transport is of paramount importance, being at the basis of electronics. Nonetheless, in recent years, the quantum theroy of transport has become more and more relevant. In fact, due to the novel experimental capabilities, it is possible to perform studies on the transport of ultracold atoms, which, under appropriate conditions (e.g. low temperatures), behave quantum mechanically. In particular, the chance to witness novel quantum effects and the possibility to change the nature of the ultracold atoms filling the lattice, from fermionic to bosonic, gives a wide variety of interesting research topics. We present here some preliminary result. Marco Baiesi - Università di Padova Response to noise variations in stochastic systems Recently there has been a considerable interest in fluctuation-response relations for nonequilibrium regimes. An example of such relations characterizes the thermal response to a variation of one temperature of a reservoir in contact with the system. For inertial systems, we show that Andersen thermostats are a natural tool for studying this kind of thermal response. For nonequilibrium overdamped systems it is also possible to derive fluctuation-response relations. We discuss the common theme characterizing these formulas. Victor Buendia Ruiz-Azuaga - Università di Parma e Universidad de Granada Limited role of spatial self-structuring in emergent trade-offs during pathogen evolution Pathogen transmission and virulence are main evolutionary variables broadly assumedto be linked through trade-offs. In well-mixed populations, these trade-offs are often ascribed to physiological restrictions, while populations with spatial self-structuring might evolve emergent trade-offs. Here, we reexamine a model of the latter kind proposed by Ballegooijen and Boerlijst with the aim of characterising the mechanisms causing the emergence of the trade-off and its structural robustness. Using invadability criteria, we establish the conditions under which an evolutionary feedback between transmission and virulence mediated by pattern formation can poise the system to a critical boundary separating a disordered state (without emergent trade-off) from a self-structured phase (where the trade-off emerges), and analytically calculate the functional shape of the boundary in a certain approximation. Beyond evolutionary parameters, the success of an invasion depends on the size and spatial structure of the invading and invaded populations. Spatial self-structuring is often destroyed when hosts are mobile, changing the evolutionary dynamics to those of a well-mixed population. In a metapopulation scenario, the systematic extinction of the pathogen in the disordered phase may counteract the disruptive effect of host mobility, favour pattern formation and therefore recover the emergent trade-off. Davide Emilio Galli - Università degli Studi di Milano Quantum Critical Behavior of One-Dimensional Soft Bosons in the Continuum We have investigated [1] a 1D system of bosons interacting via a soft-shoulder potential in the continuum, typical of dressed Rydberg gases. The flatness of the potential at short distances introduces a typical length, such that, at relatively high densities and sufficiently strong interactions, clusters are formed, even in the presence of a completely repulsive potential. We employ quantum Monte Carlo simulations, which allow for the exact calculation of imaginary-time correlations, and a stochastic analytic continuation method, to extract the dynamical structure factor. At finite densities, in the weakly interacting homogeneous regime, a rotonic spectrum marks the tendency to clustering. With strong interactions, we indeed observe cluster liquid phases emerging, characterized by the spectrum of a composite harmonic chain. Luttinger theory has to be adapted by changing the reference lattice density field. In both the liquid and cluster liquid phases, for two-particle clusters we find convincing evidence of a secondary mode, which becomes gapless only at the transition. In that region, we also measure the central charge and observe its increase towards c=3/2, and we note a fast reduction of the Luttinger parameter. We interpret such observations in terms of the compresence of a Luttinger liquid and a critical transverse Ising model, related to the instability of the reference lattice density field towards coalescence of couples of particles. Even in the absence of a true lattice, we are able to evaluate the spatial correlation function of a suitable pseudospin operator, which manifests ferromagnetic order in the cluster liquid phase, exponential decay in the liquid phase, and algebraic order at criticality. [1] S. Rossotti, M. Teruzzi, D. Pini, D.E. Galli, and G. Bertaina Phys. Rev. Lett. 119, 215301 (2017). Manuele Onofri - Università degli Studi dell’Insubria Simulations on a persistent random walk on an averaged environment for the Lévy-Lorentz gas We present results of simulations concerning the averaged Lévy-Lorentz gas. Both from analytical and numerical results we notice, depending on $\alpha$, two different regimes, one described by normal diffusion ($\alpha>1$) and the other by superdiffusion ($\alpha<1$). For the normal regime we obtain a good agreement between simulations and analytical results over the entire range $1<\alpha<2$, while in the anomalous case we discuss how finite time simulations can hardly reproduce correctly the asymptotic results. Joint work with R. Artuso, G. Cristadoro and M. Radice Francesco Petiziol - Università di Parma Structure of counterdiabatic fields and approximate counterdiabatic driving Adiabatic processes are ubiquitous in quantum science, and they are a crucial resource in the field of time-dependent quantum control. However, the limitations imposed by coherence times are typically in sharp contrast with the necessity of slow evolutions. In recent years, various methods have been proposed for speeding up adiabatic processes. A most promising one, known as method of the couterdiabatic fields or transitionless quantum driving, suggests to add a control field which compensates exactly for non-adiabatic transitions at all times. Unfortunately, in most cases of interest the correcting field turns out to involve interactions not included among the initial control possibilities. We investigate more in detail how the matrix structure of the correcting field is related to the initial set of controllable Hamiltonians. Building on such results, we discuss the possibility of realizing it in an approximate manner, by means of the available control resources. We then propose an explicit method for realizing an approximate counterdiabatic driving. Marco Pretti - ISC-CNR, Torino Dynamical transition in the TASEP with Langmuir kinetics: mean-field theory We study the dynamical transition in the Totally Asymmetric Simple Exclusion Process with open boundaries. Such a phenomenon is characterized by a singularity in the relaxation rate of the system to its non-equilibrium steady state. In the high-density (low-density) phase, the relaxation rate becomes independent of the injection (extraction) rate, at a certain critical value of the parameter. This transition is not accompanied by any change in the steady state. We provide rigorous bounds for the relaxation rate that become tight in the infinite size limit. We generalize these results to the TASEP with Langmuir kinetics, where particles can also bind to an empty site and unbind from an occupied one, at given rates. We restrict the analysis to the symmetric case of equal binding/unbinding rates and show that a dynamical transition occurs in this case as well. Anjan Roy - Università degli Studi dell’Insubria Bacterial populations with growth heterogeneity We numerically studied gene regulation models in bacterial systems which show growth bi-stability, at the level of a single cell and extended it to two types of population set-ups popular with experimentalists, namely, the Chemostat (or continuous culture) and a microfluidic device called the Mother Machine. We find that typically measured quantities such as growth rates, switching rates, distribution of proteins and hysteresis curves, have distinctive signatures at the single cell and population levels. In the process we also developed a highly efficient version of Gillespie's Stochastic Simulation Algorithm, which makes simulating large population of cells possible. Michele Tizzani - Università di Parma Epidemics Spreading on temporal networks with memory effects Activity Driven models are an interesting class of temporal networks. They are characterized by assigning to each node an activity, easily measured from extensive datasets, that represents the number of activation per time of a node [1]. Strong ties and rules for links formations in activity driven networks can be encoded in a memory function that represent the probability for a node, that has already been in contact with a certain number of different nodes, to establish a new link. The memory function has been extensively measured from real datasets and it has been shown to reproduce well the asymptotic evolution of several real temporal networks [2]. In activity driven networks without memory effects, epidemic models can be analytically studied due to the fully mean field nature of the model [1]. Here, we perform a detailed analysis of the SIR and SIS models on activity driven networks with memory. We show that, in general, memory effects lower the epidemic threshold, promoting infection spreading, as already shown in [3] for a single value of the memory parameters. Interestingly, we also show that memory induces non ergodic effects in the dynamics: the value of the epidemic threshold strongly depends on the starting time of the epidemic spreading. Despite this complex dynamical behavior, we are able to provide an analytic description of the epidemic thresholds when the epidemics starts at a very large value of the average degree of the time integrated network. In this case, the creation of new connections becomes very unlikely so that the epidemics evolve on an effective static network. The static network is characterized by a large connectivity so that a suitable site dependent mean field approach can be applied as well and we can formulate the activity based mean field model (ABMF). In this framework the epidemic process can be seen as an activity driven process evolving on the effective static network. We compare numerical simulations with analytical predictions showing a quite good agreement in the ABMF regime. Surprisingly for strong memory, the value of the threshold tends to the memoryless system. This is due to the fact that, in the effective static networks, large activity nodes are also the most connected and this amplifies the effects of the activity fluctuations. In this framework, degree fluctuations vanishes increasing the memory parameter. On the other hand, for small values of the memory the static networks is maximally heterogeneous in the degree, providing a maximal difference between the analytic prediction and the threshold of the memoryless case. [1] Perra N, Gonçalves B, Pastor-Satorras R, Vespignani A. Activity driven modeling of time varying networks. Scientific Reports. 2012;2:469. doi:10.1038/srep00469. [2] Ubaldi E, Perra N, Karsai M, Vezzani A, Burioni R, Vespignani A. Asymptotic theory of time-varying social networks with heterogeneous activity and tie allocation. Scientific Reports. 2016;6:35724. doi:10.1038/srep35724. [3] Kaiyuan Sun, Andrea Baronchelli, and Nicola Perra, Contrasting eects of strong ties on sir and sis processes in temporal networks, The European Physical Journal B 88 (2015), no. 12, 326. Pablo Villegas - Universidad de Granada Landau Ginzburg theory of cortex dynamics: Scale-free avalanches emerge at the edge of synchronization The human cortex operates in a state of restless activity, the meaning and functionality of which are still not understood. A fascinating, though controversial, hypothesis, partially backed by empirical evidence, suggests that the cortex might work at the edge of a phase transition, from which important functional advantages stem. However, the nature of such a transition remains elusive. Here, we adopt ideas from the physics of phase transitions to construct a general (Landau Ginzburg) theory of cortical networks, allowing us to analyze their possible collective phases and phase transitions. We conclude that the empirically reported scale-invariant avalanches can possibly come about if the cortex operated at the edge of a synchronization phase transition, at which neuronal avalanches and incipient oscillations coexist. Alexander Wagner - Ruprecht-Karls-Universität, Heidelberg Topological effects in quantum walks of a BEC

## Venue

The conference will take place in the Conference center in the "Aule delle Scienze" Building (Pad. 25, also called "Plesso o Polo "Q02"), number   23    in the figure on the right. The Building "Aule delle Scienze" is the first structure that can be seen when you are entering the University Campus from Viale G.P. Usberti, immediately after the main gate.

The Physics Building   16   of the Department of Mathematical, Physical and Computer Sciences is netx to "Aule delle Scienze", behind the second BUS stop inside the Campus.

## How to get there

• By Bus (from the railway station of Parma):
From the Parma station, take bus N. 21 (20 min trip) N. 7 (25 min trip). The destination is (see above the front windshield of buses) UNIVERSITÀ SUD. Be careful not to take the wrong direction. Each line has a frequency of about 7 min, between 7:00 and 19:45, less frequent in August and September.
All buses enter and exit the Campus through the main gate (viale G.P. Usberti). The nearest stop to the Conference Center is the first one, immediately after the Campus gate and the shopping center, but you can get off also at the second stop after the gate, in front of the Physics Building.
Bus timetables from station to Campus available here. Urban tickets can be purchased at ticket offices and in shops (cafés, tobacco shops, newsstands, etc) displaying the relevant sign. For an extra charge and with the exact change, it is also possible to buy the ticket on the bus.
Below you can find the timetables for the buses leaving from Campus (transport service operates 6:30 AM through 8:00 PM) More bus timetables and routes can be found on Parma's public transport website (in Italian only, sorry about that!).
• Automobile
Coming from Milan (A1 motorway) - exit at 'Parma Ovest', take the Via Emilia Ovest, then turn right onto Tangenziale Sud and follow the direction: Campus/Langhirano.
Coming from Bologna or from Verona (A1 motorway): - take 'Parma Nord' exit, turn right onto Tangenziale Nord, then follow the indications to La Spezia/Campus/Langhirano. From Tangenziale take exit n. 15 (Langhirano/Campus). This exit leads to a large round-about, take its first exit, marked “Campus”. Go straight on, across a small round-about, and enter the University gate.
• By Train
Parma is connected to the rest of Italy, France, Austria, Germany and Switzerland by high speed trains. For timetable and ticket purchase see http://www.trenitalia.com and https://www.italotreno.it.
• By Air
The airport in Parma is about 10 Km from Campus. It is linked to the railway station, the main hotels of Parma and downtown by the Aerobus, a bus service that offers a run for each departure or arrival flight. Parma can be reached from the following airports: Bologna (BLQ), Milano Linate (LIN), Milano Malpensa (MXP) e Bergamo Orio al Serio (BGY).

## Where to eat

In our Campus you can find two University Cafeteria (Mensa) are present, which are freely accessible (number   2    and   5    on the above map). Near both Cafeteria there are two Cafes with quick lunches.
Moreover, immediately outside the gates of the Campus (gate viale G.P. Usberti) there is a shopping center, with a Cafe and a bakery. Other restaurants can be found within 5 min walk, near the Cinema.

## Accommodation

• Special Hotel Rates. The hotels listed below offer a special rate to academics visiting the University of Parma or taking part in a conference: Button, Savoy, Stendhal, Torino, Toscanini (click on the name of the hotel to be redirected to the relevant webpage). Participants in the conference are kindly requested to make a reservation directly with the hotel of their choice.
• More Hotels in Parma. Click here to open an online booking website.