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An introduction to hydrodynamic spin lattices
No full textThis article is an introduction for non-specialist readers to hydrodynamic spin lattices, collections of macroscopic wave-propelled particles that exhibit symmetry-breaking phenomena. Hydrodynamic spin lattices have been introduced
and thoroughly investigated with both experiments and theoretical models by S´aenz et al. (Nature, 596 (2021) 58). Here I summarize the main results obtained in experiments with one-dimensional lattices and describe the simplest theoretical model, i.e., the generalized Kuramoto model, that captures the experimental data. The results presented here include transitions from antiferromagnetic to ferromagnetic order obtained by varying lattice geometry and system rotation, which is equivalent to applying a magnetic field. Finally, hydrodynamic spin lattices are briefly
discussed in the context of active systems
Detector characterization for LEGEND-200 experiment
No full textThe LEGEND Collaboration is developing an experimental search for the neutrinoless double-beta (0νββ) decay of the 76Ge isotope. Its first phase, LEGEND-200, uses 200 kg of 76Ge-enriched high-purity germanium detectors in an active liquid argon shield and is currently under construction at the Laboratori Nazionali del Gran Sasso (LNGS) of the INFN in Italy. Inverted coaxial pointcontact detectors are deployed in the experiment. Their unique geometry provides
an excellent energy resolution in a broad energy range and impressive discrimination of signal against background events. LEGEND’s search for 0νββ requires a precise
understanding of the behavior of germanium detectors, necessitating extensive detector characterization. The acceptance tests aim to verify whether the performance of the delivered detectors meets specifications and to determine their optimal operational parameters. We discuss the first results in the characterization program
Medium-scale anisotropies in the arrival directions of UHECRs observed by the Pierre Auger Observatory
No full textThe most prominent obstacle to identifying the sources of UltraHigh-Energy Cosmic Rays (UHECRs) is their incredibly low flux. For this reason, the Pierre Auger Observatory covers an area of ∼3000 km2 and, in its 17 years of
operation, has collected over 2600 UHECR events with energies above 32 EeV. In this contribution, I present the search of this dataset for anisotropies on medium scales of a few tenths of degrees in the arrival directions of UHECRs. Evidence for an overdensity in the Centaurus region of the sky is obtained at the 4σ significance level; this evidence is corroborated by a catalog-based likelihood ratio analysis comparing the dataset against the distribution of the closest radiogalaxies and starburst galaxies
A pseudo-spectral numerical approach to solve the Einstein field equations
No full textIn this paper, we present a numerical study of the Einstein field equations, based on the 3 + 1 foliation of the spacetime. A pseudo-spectral technique has been employed for simulations in vacuum conditions, within the formalism of Baumgarte-Shapiro-Shibata-Nakamura (BSSN). We use the Spectral-FIltered Numerical Gravity codE (SFINGE), a numerical code based on the Fourier decomposition, accompanied by different filtering techniques. The accuracy of the model has been validated through standard testbeds, revealing that the filtered pseudo-spectral technique is incredibly accurate. We evolved black hole dynamics in vacuum conditions, in small domains, making use of hyperviscous dissipation that suppresses spurious boundary problems. This simple algorithm can be applied to a variety of gravitational problems, including those related to massive objects dynamics
Molecules deposition on highly reactive surfaces: The case study of porphyrins on Fe(001)
No full textThe choice of low-interacting substrates to support a molecular layer is extremely relevant for the realization of working devices, especially when molecules with an open structure, such as metal tetraphenylporphyrins (MTPP), are used. Conversely, in the present work, I employ a prototypical highly reactive substrate (such as Fe(001)) to weight its influence on the structural and electronic
properties of deposited molecules. To this goal, I have exploited photoemission spectroscopy (XPS and UPS, porphyrin core and valence states properties), NearEdge X-ray Absorption Fine Structure spectroscopy (NEXAFS, molecule orientation with respect to the buried substrate) and scanning tunneling microscopy (STM, MTPP assembling properties) on three different MTPP molecules (namely, ZnTPP, CoTPP and VOTPP). While Zn- and CoTPP shows basically a planar configuration, VOTPP has the oxygen atom placed outside the main tetra-pyrrole ring, which can influence the molecules assembling on clean substrate
Kinematics and rotation of a vortex lattice in a polariton fluid
No full textWe study the kinematic properties of a rotating vortex lattice imprinted on a freely expanding polariton quantum fluid. Thanks to the optical component of polaritons, we can directly measure the phase and modulus of the complex-valued macroscopic wavefunction, and extract the velocity and angular momentum profiles across the condensate. These are in agreement with quantisation prescription, although the non-uniform and unsteady background density profile may induce corrections to the vortex trajectories, and result into fractional orbital angular momentum per particle
Different distinguishability quantifiers for quantum non-Markovianity
No full textIn this note, the definitions of quantum non-Markovianity based on the monotonicity of distinguishability quantifiers between two evolving quantum states are discussed. In particular, we elaborate on going beyond the commonly used trace distance and using entropic quantifiers
Radiation squeezing in interacting quantum Hall edge channels
No full textA mesoscopic system emits microwaves when subject to a periodic drive in the GHz range. The quantum features of this emitted radiation, such as squeezing, can be accessed by measuring the finite frequency photo-assisted noise in a quantum point contact geometry. In this context, we theoretically investigate the robustness of these quantum properties against electron-electron interaction using
quantum Hall edge channels at ν = 2 as the testbed
A digital holographic technique for studying mineral dust content in snow and ice cores
No full textWe propose a digital in-line holographic technique for accurate particle-by-particle characterization of airborne particles stored in meltwater samples from the cryosphere. Deriving information about particle shapes is critical to
determine the intrinsic optical properties of dust, which are of great importance to increase the knowledge about aerosols and their contribution to radiative transfer
through the atmosphere. To this end, digital holography has proven to be an excellent suite for distinguishing non-spherical particles, going beyond the common spherical approximation. It ensures a simultaneous measurement of particle crosssectional area and extinction cross-section, which are important proxies in paleoclimate research and relevant to quantyifing the particle role in radiative forcing
Flexible microelectrode array based on PEDOT:PSS for neural recording and stimulation
No full textFlexible microelectrode arrays placed on the surface of the brain cortex are promising tools for treating neurological deficits and restoring lost functionalities. Modern microfabrication techniques offer great possibilities to achieve high spatial and temporal resolution, but the device performances are ultimately determined by the material chosen as the biotic/abiotic interface. The conductive
polymer poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS) is a favorable material to use for this scope, due to its biocompatibility,
long-term stability, and large charge injection capacity. Our research aims to realize an optimized device with flexible mechanical properties and low-impedance
electrodes enabling efficient recording and stimulation of neural activity