Solitons and disorder-induced Anderson states are two apparently unrelated forms of wave localization, the former being due to nonlinearity and the latter to linear disorder.
However, on closer inspection, solitons and disorder induced localized states have similarities: exponential localization, negative eigenvalues, any possible position in space. In the presence of nonlinearity, disorder-induced localizations are expected to have eigenvalue and localization length dependent on power. These states, however, also exist for a negligible nonlinearity: Hence, in the low fluence regime, they are linear Anderson localizations, but at high fluence, they become related to solitons.
In Physical Review A, we analytically and numerically study the process of “solitonization of the Anderson localization,” that is smooth transition from disorder induced to nonlinearity induced wave localization in random media.
The image shows the cutting of bacteria by graphene oxide flakes.
Some Web release
The super bugs are the plague of modern era. Super bugs are antibiotic resistant bacteria that will cause the death of thousands of people in the future. We need novel tools to sterilize surfaces and medical equipment; we also need novel approaches to defeat bacteria.
Within a collaboration with the University Cattolica, we recently reported in Scientific Reports on a novel “cloak” against super bugs. The cloak is a laser printed surface that includes graphene oxide. The cloak is able to kill the bacteria because the surface mimics the carapace of the Cancer Pagurus (picture above), which is known to repel dangerous organisms, and also uses graphene as a blade that cuts the bacteria (and also wrap and poison them), as in the following picture
The cloak is a novel very effective solution to sterilize surfaces, and our research sheds light on the effect of graphene against bacteria. We report 90% bacteria killing action.
Shock waves emerge in various fields and trigger effects like rogue waves, supercontinuum generation and emission of resonant radiation. Despite shock waves ubiquity, their effect on the coherence properties is barely understood. Among the open problems, the quantum features of shock waves are particularly intriguing for the possibility of generating non-classical states by highly nonlinear regimes. In a manuscript in arXiv, Maria Chiara Braidotti, Antonio Mecozzi, and Claudio Conti theoretically predict classical squeezing of light during shock formation. The picture above shows the Wigner transform of the field in the squeezed regime. By using techniques of rigged Hilbert space quantum mechanics, they show that a coherent state develops squeezing which stops in proximity of the shock point. The analysis holds true for temporal and spatial shock waves in highly nonlocal regime.These results open a new scenario in shock phenomena and link nonlinear propagation in extreme regimes with quantum optics and related applications.