The SU(2)⊗SU(2) extension of the Jaynes–Cummings model provides a quantum mechanical system with a finite Hilbert space together with a maximum energy level in the spectrum. The model, which remains exactly solvable, is based on the replacement of the bosonic (creation and annihilation) operators by spin operators defined to act within a definite SU(2) irreducible representation, in such a way that the photon field has a finite number of excitations. The usual Heisenberg–Weyl () algebra can be obtained by contraction of the su(2) Lie algebra. We analyze the behavior of both the atomic and field quantum properties, like collapse and revivals, photon antibunching and squeezing, giving special attention to their dependence upon the maximum number of photon excitations.

The galvanic couple AA2024/Carbon Fiber Reinforced Polymer (CFRP) has been studied numerically and experimentally in a dynamic electrolyte droplet. As an electrolyte, a NaCl droplet (0.6 M initial concentration) was used at a controlled temperature (24.5°C) and relative humidity (83.5%). The evaporation of the electrolyte was monitored for 24 hours using a Scanning Kelvin Probe (SKP), simulating atmospheric corrosion phenomena. The electrochemical potential and droplet height were constantly monitored. Geometry, temperature, potential, aluminum corrosion products, pH fields, and electrochemical and physicochemical boundary conditions were all considered by finite element analysis. The experimental and numerical results showed strong correlations.

We introduce a spin model which exhibits the main properties of a Kerr medium to describe an intensity dependent coupling between a two-level atom and the radiation field. We select a unitary irreducible representation of the su(2) Lie algebra such that the number of excitations of the field is bounded from above. We analyze the behavior of both the atomic and the field quantum properties and its dependence on the maximal number of excitations.