Laser-induced optical breakdown by femtosecond pulses is extraordinarily precise when the energy is near threshold. Despite numerous applications, the basis for this deterministic nature has not been determined. We present experiments that shed light on the basic mechanisms of light-matter interactions in this regime, which we term "optics at critical intensity." We find that the remarkably sha...

The Landau-Zener formula for the probability that a nonadiabatic transition has taken place is derived without solving directly the usual second-order differential equation. This is achieved in just a few steps by using contour integration.

We introduce a new model for dark energy in the universe in which a small cosmological constant is generated by ordinary electromagnetic vacuum energy. The corresponding virtual photons exist at all frequencies but switch from a gravitationally active phase at low frequencies to a gravitationally inactive phase at higher frequencies via a Ginzburg-Landau type of phase transition. Only virtual p...

The nature of diatomic ligand recombination in heme proteins is elucidated by using a Landau-Zener model for the electronic coupling in the recombination rate constant. The model is developed by means of explicit potential energy surfaces calculated by using density functional theory (DFT). The interaction of all possible spin states of the three common diatomic ligands, CO, NO, and O2, and hig...

The microstructure stability during d sub-solvus annealing in Inconel 718 was investigated, focusing on the conditions that may lead to the development of very large grains (about 100 lm) in a recrystallized fine grained matrix (4 to 5 lm) despite the presence of second-phase particles. Microstructure evolution was analyzed by EBSD (grain size, intragranular misorientation) and SEM (d phase par...

The present study examines the possibility of attenuating blood pulses by means of introducing prosthetic viscoelastic materials able to absorb energy and damp such pulses. Vascular prostheses made of polymeric materials modify the mechanical properties of blood vessels. The effect of these materials on the blood pulse propagation remains to be fully understood. Several materials for medical ap...

Non-adiabatic transitions in multilevel systems appear various fields of physics, but it is not easy to analyze their dynamics general. In this paper, we propose extend the adiabatic impulse approximation systems. This method shown be equivalent a series unitary evolutions and facilitates evaluate numerically. particular, Landau-Zener grid model Landau-Zener-St\"uckelberg-Majorana interference ...