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Dynamical thermalization in Bose-Hubbard systems Schlagheck, Peter ; in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2016), 93 We numerically study a Bose-Hubbard ring of finite size with disorder containing a finite number of bosons that are subject to an on-site two-body interaction. Our results show that moderate interactions ... [more ▼] We numerically study a Bose-Hubbard ring of finite size with disorder containing a finite number of bosons that are subject to an on-site two-body interaction. Our results show that moderate interactions induce dynamical thermalization in this isolated system. In this regime the individual many-body eigenstates are well described by the standard thermal Bose-Einstein distribution for well-defined values of the temperature and the chemical potential, which depend on the eigenstate under consideration. We show that the dynamical thermalization conjecture works well at both positive and negative temperatures. The relations to quantum chaos, quantum ergodicity, and the Åberg criterion are also discussed. [less ▲] Detailed reference viewed: 7 (0 ULg)Rotation of melting ice disks due to melt fluid flow Dorbolo, Stéphane ; ; Dubois, Charles et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2016) Detailed reference viewed: 18 (7 ULg)Quantum manifestations of classical nonlinear resonances ; Schlagheck, Peter in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2015), 92 When an integrable classical system is perturbed, nonlinear resonances are born, grow, and eventually disappear due to chaos. In this paper the quantum manifestations of such a transition are studied in ... [more ▼] When an integrable classical system is perturbed, nonlinear resonances are born, grow, and eventually disappear due to chaos. In this paper the quantum manifestations of such a transition are studied in the standard map. We show that nonlinear resonances act as a perturbation that break eigenphase degeneracies for unperturbed states with quantum numbers that differ in a multiple of the order of the resonance. We show that the eigenphase splittings are well described by a semiclassical expression based on an integrable approximation of the Hamiltonian in the vicinity of the resonance. The morphology in phase space of these states is also studied. We show that the nonlinear resonance imprints a systematic influence in their localization properties [less ▲] Detailed reference viewed: 12 (0 ULg)Multifractality of quantum wave functions in the presence of perturbations Dubertrand, Rémy ; ; et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2015), 92 We present a comprehensive study of the destruction of quantum multifractality in the presence of perturbations. We study diverse representative models displaying multifractality, including a ... [more ▼] We present a comprehensive study of the destruction of quantum multifractality in the presence of perturbations. We study diverse representative models displaying multifractality, including a pseudointegrable system, the Anderson model, and a random matrix model. We apply several types of natural perturbations which can be relevant for experimental implementations. We construct an analytical theory for certain cases and perform extensive large-scale numerical simulations in other cases. The data are analyzed through refined methods including double scaling analysis. Our results confirm the recent conjecture that multifractality breaks down following two scenarios. In the first one, multifractality is preserved unchanged below a certain characteristic length which decreases with perturbation strength. In the second one, multifractality is affected at all scales and disappears uniformly for a strong-enough perturbation. Our refined analysis shows that subtle variants of these scenarios can be present in certain cases. This study could guide experimental implementations in order to observe quantum multifractality in real systems. [less ▲] Detailed reference viewed: 19 (8 ULg)Resonant and antiresonant bouncing droplets Hubert, Maxime ; ; Caps, Hervé et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2015), 91 When placed onto a vibrating liquid bath, a droplet may adopt a permanent bouncing behavior, depending on both the forcing frequency and the forcing amplitude. The relationship between the droplet ... [more ▼] When placed onto a vibrating liquid bath, a droplet may adopt a permanent bouncing behavior, depending on both the forcing frequency and the forcing amplitude. The relationship between the droplet deformations and the bouncing mechanism is studied experimentally and theoretically through an asymmetric and dissipative bouncing spring model. Antiresonance phenomena are evidenced. Experiments and theoretical predictions show that both resonance at specific frequencies and antiresonance at Rayleigh frequencies play crucial roles in the bouncing mechanism. In particular, we show that they could be exploited for bouncing droplet size selection. [less ▲] Detailed reference viewed: 56 (11 ULg)Principal-component analysis of particle motion ; Liegeois, Raphaël ; et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2015) We demonstrate the application of principal-component analysis (PCA) to the analysis of particle motion data in the form of a time series of images. PCA has the ability to resolve and isolate ... [more ▼] We demonstrate the application of principal-component analysis (PCA) to the analysis of particle motion data in the form of a time series of images. PCA has the ability to resolve and isolate spatiotemporal patterns in the data. Using simulated data, we show that this translates into the ability to separate individual frequency components of the particle motion. We also show that PCA can be used to extract the fluid viscosity from images of particles undergoing Brownian motion. PCA thus provides an efficient alternative to more traditional particle-tracking methods for the analysis of microrheological data. [less ▲] Detailed reference viewed: 18 (3 ULg)Importance of wavenumber dependence of Biot numbers in one-sided models of evaporative Marangoni instability: horizontal layer and spherical droplet Machrafi, Hatim ; ; et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2015), 91 Detailed reference viewed: 34 (2 ULg)Bernal random loose packing through freeze-thaw cycling Ludewig, François ; Vandewalle, Nicolas ; Dorbolo, Stéphane et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2015) We study the effect of freeze-thaw cycling on the packing fraction of equal spheres immersed in water. The water located between the grains experiences a dilatation during freezing and a contraction ... [more ▼] We study the effect of freeze-thaw cycling on the packing fraction of equal spheres immersed in water. The water located between the grains experiences a dilatation during freezing and a contraction during melting. After several cycles, the packing fraction converges to a particular value η∞ = 0.595 independently of its initial value η0. This behavior is well reproduced by numerical simulations. Moreover, the numerical results allow one to analyze the packing structural configuration. With a Vorono ̈ı partition analysis, we show that the piles are fully random during the whole process and are characterized by two parameters: the average Vorono ̈ı volume μv (related to the packing fractionη)andthestandarddeviationσv ofVorono ̈ıvolumes.Thefreeze-thawdrivingmodifythevolumestandard deviation σv to converge to a particular disordered state with a packing fraction corresponding to the random loose packing fraction ηBRLP obtained by Bernal during his pioneering experimental work. Therefore, freeze-thaw cycling is found to be a soft and spatially homogeneous driving method for disordered granular materials. [less ▲] Detailed reference viewed: 23 (6 ULg)Armoring a droplet: Soft jamming of a dense granular interface Lagubeau, Guillaume ; ; in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2014), 90 Droplets and bubbles protected by armors of particles have found vast applications in encapsulation, stabilization of emulsions and foams, or flotation processes. The liquid phase stores capillary energy ... [more ▼] Droplets and bubbles protected by armors of particles have found vast applications in encapsulation, stabilization of emulsions and foams, or flotation processes. The liquid phase stores capillary energy, while concurrently the solid contacts of the granular network induce friction and energy dissipation, leading to hybrid interfaces of combined properties. By means of nonintrusive tensiometric methods and structural measurements, we distinguish three surface phases of increasing rigidity during the evaporation of armored droplets. The emergence of surface rigidity is reminiscent of jamming of granular matter, but it occurs differently since it is marked by a step by step hardening under surface compression. These results show that the concept of the effective surface tension remains useful only below the first jamming transition. Beyond this point, the surface stresses become anisotropic. [less ▲] Detailed reference viewed: 9 (2 ULg)Geometrical guidance and trapping transition of human sperm cells ; ; et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2014), 89 The guidance of human sperm cells under con finement in quasi 2D microchambers is investigated using a purely physical method to control their distribution. Transport property measurements and simulations ... [more ▼] The guidance of human sperm cells under con finement in quasi 2D microchambers is investigated using a purely physical method to control their distribution. Transport property measurements and simulations are performed with diluted sperm populations, for which eff ects of geometrical guidance and concentration are studied in detail. In particular, a trapping transition at convex angular wall features is identi ed and analyzed. We also show that highly efficient microratchets can be fabricated by using curved asymmetric obstacles to take advantage of the spermatozoa specifi c swimming strategy. [less ▲] Detailed reference viewed: 50 (13 ULg)Origin of the exponential decay of the Loschmidt echo in integrable systems Dubertrand, Rémy ; in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2014), 89 We address the time decay of the Loschmidt echo, measuring the sensitivity of quantum dynamics to small Hamiltonian perturbations, in one-dimensional integrable systems. Using a semiclassical analysis, we ... [more ▼] We address the time decay of the Loschmidt echo, measuring the sensitivity of quantum dynamics to small Hamiltonian perturbations, in one-dimensional integrable systems. Using a semiclassical analysis, we show that the Loschmidt echo may exhibit a well-pronounced regime of exponential decay, similar to the one typically observed in quantum systems whose dynamics is chaotic in the classical limit. We derive an explicit formula for the exponential decay rate in terms of the spectral properties of the unperturbed and perturbed Hamilton operators and the initial state. In particular, we show that the decay rate, unlike in the case of the chaotic dynamics, is directly proportional to the strength of the Hamiltonian perturbation. Finally, we compare our analytical predictions against the results of a numerical computation of the Loschmidt echo for a quantum particle moving inside a one-dimensional box with Dirichlet-Robin boundary conditions, and find the two in good agreement. [less ▲] Detailed reference viewed: 9 (0 ULg)Leidenfrost effect: Accurate drop shape modeling and refined scaling laws ; ; Dorbolo, Stéphane et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2014), 90 Detailed reference viewed: 20 (2 ULg)Dynamics and statistics of wave-particle interactions in a confined geometry Gilet, Tristan in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2014), 90 Detailed reference viewed: 19 (4 ULg)How dynamical clustering triggers Maxwell's demon in microgravity Opsomer, Eric ; Noirhomme, Martial ; Vandewalle, Nicolas et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2013), 88 In microgravity, the gathering of granular material can be achieved by a dynamical clustering whose existence depends on the geometry of the cell that contains the particles and the energy that is ... [more ▼] In microgravity, the gathering of granular material can be achieved by a dynamical clustering whose existence depends on the geometry of the cell that contains the particles and the energy that is injected into the system. By compartmentalizing the cell in several subcells of smaller volume, local clustering is triggered and the so formed dense regions act as stable traps. In this paper, molecular dynamics simulations were performed in order to reproduce the phenomenon and to analyze the formation and the stability of such traps. Depending on the total number N of particles present in the whole system, several clustering modes are encountered and a corresponding bifurcation diagram is presented. Moreover, an iterative model based on the measured particle flux F as well as a theoretical model giving the asymptotical steady states are used to validate our results. The obtained results are promising and can provide ways to manipulate grains in microgravity. [less ▲] Detailed reference viewed: 26 (8 ULg)Melting of a confined monolayer of magnetized beads Schockmel, Julien ; ; Vandewalle, Nicolas et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2013) Detailed reference viewed: 68 (18 ULg)Influence of swimming strategy on microorganism separation by asymmetric obstacles ; ; et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2013), 87 It has been shown that a nanoliter chamber separated by a wall of asymmetric obstacles can lead to an inhomogeneous distribution of self-propelled microorganisms. Although it is well established that this ... [more ▼] It has been shown that a nanoliter chamber separated by a wall of asymmetric obstacles can lead to an inhomogeneous distribution of self-propelled microorganisms. Although it is well established that this rectification effect arises from the interaction between the swimmers and the noncentrosymmetric pillars, here we demonstrate numerically that its efficiency is strongly dependent on the detailed dynamics of the individual microorganism. In particular, for the case of run-and-tumble dynamics, the distribution of run lengths, the rotational diffusion, and the partial preservation of run orientation memory through a tumble are important factors when computing the rectification efficiency. In addition, we optimize the geometrical dimensions of the asymmetric pillars in order to maximize the swimmer concentration and we illustrate how it can be used for sorting by swimming strategy in a long array of parallel obstacles. [less ▲] Detailed reference viewed: 36 (0 ULg)Semiclassical description of resonance-assisted tunneling in one-dimensional integrable models ; ; Schlagheck, Peter in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2013), 88 Resonance-assisted tunneling is investigated within the framework of one-dimensional integrable systems. We present a systematic recipe, based on Hamiltonian normal forms, to construct one-dimensional ... [more ▼] Resonance-assisted tunneling is investigated within the framework of one-dimensional integrable systems. We present a systematic recipe, based on Hamiltonian normal forms, to construct one-dimensional integrable models that exhibit resonance island chain structures with accurately controlled sizes and positions of the islands. Using complex classical trajectories that evolve along suitably defined paths in the complex time domain, we construct a semiclassical theory of the resonance-assisted tunneling process. This semiclassical approach yields a compact analytical expression for tunnelling-induced level splittings which is found to be in very good agreement with the exact splittings obtained through numerical diagonalization. [less ▲] Detailed reference viewed: 24 (0 ULg)Multifractality of quantum wave packets ; Martin, John ; et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2012), 86 We study a version of the mathematical Ruijsenaars-Schneider model and reinterpret it physically in order to describe the spreading with time of quantum wave packets in a system where multifractality can ... [more ▼] We study a version of the mathematical Ruijsenaars-Schneider model and reinterpret it physically in order to describe the spreading with time of quantum wave packets in a system where multifractality can be tuned by varying a parameter. We compare different methods to measure the multifractality of wave packets and identify the best one. We find the multifractality to decrease with time until it reaches an asymptotic limit, which is different from the multifractality of eigenvectors but related to it, as is the rate of the decrease. Our results could guide the study of experimental situations where multifractality is present in quantum systems. [less ▲] Detailed reference viewed: 91 (4 ULg)Trace formula for dielectric cavities. III. TE modes ; Dubertrand, Rémy in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2012), 86 The construction of the semiclassical trace formula for resonances with transverse electric polarization for two-dimensional dielectric cavities is discussed. Special attention is given to the derivation ... [more ▼] The construction of the semiclassical trace formula for resonances with transverse electric polarization for two-dimensional dielectric cavities is discussed. Special attention is given to the derivation of the two first terms of Weyl’s series for the average number of such resonances. The formulas obtained agree well with numerical calculations for dielectric cavities of different shapes. [less ▲] Detailed reference viewed: 13 (0 ULg)Trace formula for chaotic dielectric resonators tested with microwave experiments ; ; Dubertrand, Rémy et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2012), 85 We measured the resonance spectra of two stadium-shaped dielectric microwave resonators and tested a semiclassical trace formula for chaotic dielectric resonators proposed by Bogomolny et al. [Phys. Rev ... [more ▼] We measured the resonance spectra of two stadium-shaped dielectric microwave resonators and tested a semiclassical trace formula for chaotic dielectric resonators proposed by Bogomolny et al. [Phys. Rev. E 78, 056202 (2008)]. We found good qualitative agreement between the experimental data and the predictions of the trace formula. Deviations could be attributed to missing resonances in the measured spectra in accordance with previous experiments [Phys. Rev. E 81, 066215 (2010)]. The investigation of the numerical length pectrum showed good qualitative and reasonable quantitative agreement with the trace formula. It demonstrated, however, the need for higher-order corrections of the trace formula. The application of a curvature correction to the Fresnel reflection coefficients entering the trace formula yielded better agreement, but deviations remained, indicating the necessity of further investigations. [less ▲] Detailed reference viewed: 7 (0 ULg) |
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