Mean field limit for bosons and propagation of Wigner measures

We consider the N-body Schr\"{o}dinger dynamics of bosons in the mean field limit with a bounded pair-interaction potential. According to the previous work \cite{AmNi}, the mean field limit is translated into a semiclassical problem with a small parameter $\epsilon\to 0$, after introducing an $\epsilon$-dependent bosonic quantization. The limit is expressed as a push-forward by a nonlinear flow (e.g. Hartree) of the associated Wigner measures. These object and their basic properties were introduced in \cite{AmNi} in the infinite dimensional setting. The additional result presented here states that the transport by the nonlinear flow holds for rather general class of quantum states in their mean field limit.Comment: 10 page

History-dependent relaxation and the energy scale of correlation in the Electron-Glass

We present an experimental study of the energy-relaxation in Anderson-insulating indium-oxide films excited far from equilibrium. In particular, we focus on the effects of history on the relaxation of the excess conductance dG. The natural relaxation law of dG is logarithmic, namely dG=-log(t). This may be observed over more than five decades following, for example, cool-quenching the sample from high temperatures. On the other hand, when the system is excited from a state S_{o} in which it has not fully reached equilibrium to a state S_{n}, the ensuing relaxation law is logarithmic only over time t shorter than the time t_{w} it spent in S_{o}. For times t>t_{w} dG(t) show systematic deviation from the logarithmic dependence. It was previously shown that when the energy imparted to the system in the excitation process is small, this leads to dG=P(t/t_{w}) (simple-aging). Here we test the conjecture that `simple-aging' is related to a symmetry in the relaxation dynamics in S_{o} and S_{n}. This is done by using a new experimental procedure that is more sensitive to deviations in the relaxation dynamics. It is shown that simple-aging may still be obeyed (albeit with a modified P(t/t_{w})) even when the symmetry of relaxation in S_{o} and S_{n} is perturbed by a certain degree. The implications of these findings to the question of aging, and the energy scale associated with correlations are discussed

Deposition And Drying Dynamics Of Liquid Crystal Droplets

Drop drying and deposition phenomena reveal a rich interplay of fundamental science and engineering, give rise to fascinating everyday effects (coffee rings), and influence technologies ranging from printing to genotyping. Here we investigate evaporation dynamics, morphology, and deposition patterns of drying lyotropic chromonic liquid crystal droplets. These drops differ from typical evaporating colloidal drops primarily due to their concentration-dependent isotropic, nematic, and columnar phases. Phase separation occurs during evaporation, and in the process creates surface tension gradients and significant density and viscosity variation within the droplet. As a result, the drying multiphase drops exhibit different convective currents, drop morphologies, and deposition patterns (coffee-rings)

A Methodology for Abstracting the Physical Layer of Direct V2X Communications Technologies

Recent advancements in vehicle-to-everything (V2X) communications have greatly increased the flexibility of the physical (PHY) and medium access control (MAC) layers. This increases the complexity when investigating the system from a network perspective to evaluate the performance of the supported applications. Such flexibility, in fact, needs to be taken into account through a cross-layer approach, which might lead to challenging evaluation processes. As an accurate simulation of the signals appears unfeasible, a typical solution is to rely on simple models for incorporating the PHY layer of the supported technologies based on off-line measurements or accurate link-level simulations. Such data are, however, limited to a subset of possible configurations, and extending them to others is costly when not even impossible. The goal of this paper is to develop a new approach for modeling the PHY layer of V2X communications that can be extended to a wide range of configurations without leading to extensive measurement or simulation campaigns at the link layer. In particular, given a scenario and starting from results in terms of the packet error rate (PER) vs. signal-to-interference-plus-noise ratio (SINR) related to a subset of possible configurations, we first approximated the curves with step functions characterized by a given SINR threshold, and we then derived one parameter, called implementation loss, that was used to obtain the SINR threshold and evaluate the network performance under any configuration in the same scenario. The proposed methodology, leading to a good trade-off among the complexity, generality, and accuracy of the performance evaluation process, was validated through extensive simulations with both IEEE 802.11p and LTE-V2X sidelink technologies in various scenarios. The results first show that the curves can be effectively approximated by using an SINR threshold, with a value corresponding to 0.5 PER, and then demonstrate that the network-level outputs derived from the proposed approach are very close to those obtained with complete curves, despite not being restricted to a few possible configurations

Geometrical factor in multi-interface homostructures

In an experimental investigation carried out on multilayer silicon homostructures (of the n+-n-n+ type) an electric interaction between the two homointerfaces through majority carriers as a function of the geometrical factor has been shown. The two model homointerfaces were formed in the same monocrystal (CVD epitaxy) by only an abrupt change in the impurity doping level. Samples differing in the spacing of their parallel interfaces were characterized in the stationary and steady states (static and quasi-static regimes) to reveal modifications in their macroscopic transport. It has been demonstrated that the thermionic emission current, normally taken into account in the barrier transport (with large potential barriers) dominates in only two of five characteristic bias intervals. The two other phenomena, also related to the geometrical factor, i.e. the diffusion-drift and tunneling currents, dominate the conduction over practically the whole dc-bias range. These results allow the study of short and long range electrical interactions as well as the free carrier micromovement of simple and complex semiconductor interfaces of multilayer devices

SU(4) symmetry breaking revealed by magneto-optical spectroscopy in epitaxial graphene

Refined infrared magnetotransmission experiments have been performed in magnetic fields B up to 35 T on a series of multilayer epitaxial graphene samples. Following the main optical transition involving the n=0 Landau level (LL), we observe a new absorption transition increasing in intensity with magnetic fields B>26 T. Our analysis shows that this is a signature of the breaking of the SU(4) symmetry of the n=0 LL. Using a quantitative model, we show that the only symmetry-breaking scheme consistent with our experiments is a charge density wave (CDW)

Comparison of 35 and 50 {\mu}m thin HPK UFSD after neutron irradiation up to 6*10^15 neq/cm^2

We report results from the testing of 35 {\mu}m thick Ultra-Fast Silicon Detectors (UFSD produced by Hamamatsu Photonics (HPK), Japan and the comparison of these new results to data reported before on 50 {\mu}m thick UFSD produced by HPK. The 35 {\mu}m thick sensors were irradiated with neutrons to fluences of 0, 1*10^14, 1*10^15, 3*10^15, 6*10^15 neq/cm^2. The sensors were tested pre-irradiation and post-irradiation with minimum ionizing particles (MIPs) from a 90Sr \b{eta}-source. The leakage current, capacitance, internal gain and the timing resolution were measured as a function of bias voltage at -20C and -27C. The timing resolution was extracted from the time difference with a second calibrated UFSD in coincidence, using the constant fraction method for both. Within the fluence range measured, the advantage of the 35 {\mu}m thick UFSD in timing accuracy, bias voltage and power can be established.Comment: 9 pages, 9 figures, HSTD11 Okinawa. arXiv admin note: text overlap with arXiv:1707.0496

Analysis of Co-Channel Coexistence Mitigation Methods Applied to IEEE 802.11p and 5G NR-V2X Sidelink

Direct communication between vehicles and surrounding objects, called vehicle-to-everything (V2X), is ready for the market and promises to raise the level of safety and comfort while driving. To this aim, specific bands have been reserved in some countries worldwide and different wireless technologies have been developed; however, these are not interoperable. Recently, the issue of co-channel coexistence has been raised, leading the European Telecommunications Standards Institute (ETSI) to propose a number of solutions, called mitigation methods, for the coexistence of the IEEE 802.11p based ITS-G5 and the 3GPP fourth generation (4G) long term evolution (LTE)-V2X sidelink. In this work, several of the envisioned alternatives are investigated when adapted to the coexistence of the IEEE 802.11p with its enhancement IEEE 802.11bd and the latest 3GPP standards, i.e., the fifth generation (5G) new radio (NR)-V2X. The results, obtained through an open-source simulator that is shared with the research community for the evaluation of additional proposals, show that the methods called A and C, which require modifications to the standards, improve the transmission range of one or both systems without affecting the other, at least in low-density scenarios

Time Dependent Development of the Coulomb Gap

We show that the time development of the Coulomb gap in a Coulomb glass can involve very long relaxation times due to electron rearrangement and hopping. We find that an applied magnetic field reduces the rate of electron hopping and, hence, Coulomb gap formation. These results are consistent with recent conductance experiments on thin semiconducting and metallic films.Comment: 4 pages, Latex, 3 encapsulated postscript figure