Observation of replica symmetry breaking in disordered nonlinear wave propagation

A landmark of statistical mechanics, spin-glass theory describes critical phenomena in disordered systems that range from condensed matter to biophysics and social dynamics. The most fascinating concept is the breaking of replica symmetry: identical copies of the randomly interacting system that manifest completely different dynamics. Replica symmetry breaking has been predicted in nonlinear wave propagation, including Bose-Einstein condensates and optics, but it has never been observed. Here, we report the experimental evidence of replica symmetry breaking in optical wave propagation, a phenomenon that emerges from the interplay of disorder and nonlinearity. When mode interaction dominates light dynamics in a disordered optical waveguide, different experimental realizations are found to have an anomalous overlap intensity distribution that signals a transition to an optical glassy phase. The findings demonstrate that nonlinear propagation can manifest features typical of spin-glasses and provide a novel platform for testing so-far unexplored fundamental physical theories for complex systems

Anti-diffracting beams through the diffusive optical nonlinearity

Anti-diffraction is a theoretically predicted nonlinear optical phenomenon that occurs when a light beam spontaneously focalizes independently of its intensity. We observe anti-diffracting beams supported by the peak-intensity-independent diffusive nonlinearity that are able to shrink below their diffraction-limited size in photorefractive lithium-enriched potassium-tantalate-niobate (KTN:Li)

Aging solitons in photorefractive dipolar glasses

We study experimentally the aging of optical spatial solitons in a dipolar glass hosted by a nanodisordered sample of photorefractive potassium-sodium-tantalate-niobate (KNTN). As the system ages, the waves erratically explore varying strengths of the nonlinear response, causing them to break up and scatter. We show that this process can still lead to solitons, but in a generalized form for which the changing response is compensated by changing the normalized wave size and intensity so as to maintain fixed the optical waveform

Super-crystals in composite ferroelectrics

As atoms and molecules condense to form solids, a crystalline state can emerge with its highly ordered geometry and subnanometric lattice constant. In some physical systems, such as ferroelectric perovskites, a perfect crystalline structure forms even when the condensing substances are non-stoichiometric. The resulting solids have compositional disorder and complex macroscopic properties, such as giant susceptibilities and non-ergodicity. Here, we observe the spontaneous formation of a cubic structure in composite ferroelectric potassium– lithium–tantalate–niobate with micrometric lattice constant, 104 times larger than that of the underlying perovskite lattice. The 3D effect is observed in specifically designed samples in which the substitutional mixture varies periodically along one specific crystal axis. Laser propagation indicates a coherent polarization super-crystal that produces an optical X-ray diffractometry, an ordered mesoscopic state of matter with important implications for critical phenomena and applications in miniaturized 3D optical technologies

Observation of an intrinsic nonlinearity in the electro-optic response of freezing relaxors ferroelectrics

We demonstrate an electro-optic response that is linear in the amplitude but independent of the sign of the applied electric field. The symmetry-preserving linear electro-optic effect emerges at low applied electric fields in freezing nanodisordered KNTN above the dielectric peak temperature, deep into the nominal paraelectric phase. Strong temperature dependence allows us to attribute the phenomenon to an anomalously reduced thermal agitation in the reorientational response of the underlying polar-nanoregions

Cancer mortality trend in central Italy. focus on a “low rate of land use” area from 1982 to 2011

The aim of the present study was to estimate total cancer mortality trends from 1982 to 2011 in a “low rate of land use” province of the Latium region (Rieti, central Italy) characterized by a low degree of urbanization, a high prevalence of elderly, and a low number of births. Mortality data of the studied period, provided by the Italian National Institute of Statistics, were used for calculating standardized cancer mortality rates. Trends in mortality were analyzed using Joinpoint regression analysis. Results showed that total standardized cancer mortality rates decreased in the monitored area over the study period. A comparison with other provinces of the same region evidenced that the studied province presented the lowest cancer mortality. The three systems/apparatuses affected by cancer that mainly influenced cancer mortality in the monitored province were the trachea-bronchus-lung, colorectal-anus, and stomach. These findings could be attributed to the implement of preventive initiatives performed in the early 2000s, to healthier environmental scenario, and to lower levels of carcinogenic pollutants in air, water, and soil matrices. Thus, our results indicate that the studied area could be considered a “healthy” benchmark for studies in oncological diseases

Nonlinear optics in a high-index of refraction material

Nonlinear response in a material increases with its index of refraction as $n^4$. Commonly, $n \sim$ 1 so that diffraction, dispersion, and chromatic walk-off limit nonlinear scattering. Ferroelectric crystals with a periodic 3D polarization structure overcome some of these constraints through versatile Cherenkov and quasi-phase-matching mechanisms. Three-dimensional self-structuring can also lead to a giant broadband refraction \cite{DiMei2018}. We here perform second-harmonic-generation experiments in KTN:Li with $n>26$. Enhanced response causes wavelength conversion to occur in the form of bulk Cherenkov radiation without diffraction and chromatic walk-off, even in the presence of strong wave-vector mismatch and highly focused beams. The process occurs with an arbitrarily wide spectral acceptance, more than 100 nm in the near infrared spectrum, an ultra-wide angular acceptance, up to $\pm 40^{\circ}$, with no polarization selectivity, and can be tuned to allow bulk supercontinuum generation. Results pave the way to highly efficient versatile and adaptable nonlinear optical devices with the promise of single-photon-to-single-photon nonlinear optics.Comment: 9 pages, 5 figure

Notulae to the Italian alien vascular flora: 17

In this contribution, new data concerning the distribution of vascular flora alien to Italy are presented. It includes new records and status changes from casual to naturalized for Italy or for Italian administrative regions for taxa in the genera Callianthe, Chamaecyparis, Chamaeiris, Cotoneaster, Erigeron, Freesia, Hemerocallis, Juglans, Kalanchoë, Ludwigia, Nassella, Paulownia, Physocarpus, Pistia, Saccharum, Setaria, and Vachellia. Nomenclatural and distribution updates, published elsewhere, and corrections are provided as supplementary material

Notulae to the Italian native vascular flora: 5.

In this contribution, new data concerning the distribution of native vascular flora in Italy are presented. It includes new records and confirmations to the Italian administrative regions for taxa in the genera Allium, Arabis, Campanula, Centaurea, Chaerophyllum, Crocus, Dactylis, Dianthus, Festuca, Galanthus, Helianthemum, Lysimachia, Milium, Pteris, and Quercus. Nomenclature and distribution updates, published elsewhere, and corrections are provided as supplementary material

Subwavelength anti-diffracting beams propagating over more than 1,000 Rayleigh lengths

Propagating light beams with widths down to and below the optical wavelength require bulky large-aperture lenses and remain focused only for micrometric distances. Here, we report the observation of light beams that violate this localization/depth- of-focus law by shrinking as they propagate, allowing resolution to be maintained and increased over macroscopic propagation lengths. In nanodisordered ferroelectrics we observe a non-paraxial propagation of a sub-micrometre-sized beam for over 1,000 diffraction lengths, the narrowest visible beam reported to date. This unprecedented effect is caused by the nonlinear response of a dipolar glass, which transforms the leading opticalwave equation into a Klein-Gordon-type equation that describes a massive particle field. Our findings open the way to high-resolution optics over large depths of focus, and a route to merging bulk optics into nanodevices