Uniform materials and the multiplicative decomposition of the deformation gradient in finite elasto-plasticity

In this work we analyze the relation between the multiplicative decomposition $\mathbf F=\mathbf F^{e}\mathbf F^{p}$ of the deformation gradient as a product of the elastic and plastic factors and the theory of uniform materials. We prove that postulating such a decomposition is equivalent to having a uniform material model with two configurations - total $\phi$ and the inelastic $\phi_{1}$. We introduce strain tensors characterizing different types of evolutions of the material and discuss the form of the internal energy and that of the dissipative potential. The evolution equations are obtained for the configurations $(\phi,\phi_{1})$ and the material metric $\mathbf g$. Finally the dissipative inequality for the materials of this type is presented.It is shown that the conditions of positivity of the internal dissipation terms related to the processes of plastic and metric evolution provide the anisotropic yield criteria

An all-optical event horizon in an optical analogue of a Laval nozzle

Exploiting the fact that light propagation in defocusing nonlinear media can mimic the transonic flow of an equivalent fluid, we demonstrate experimentally the formation of an all-optical event horizon in a waveguide structure akin to a hydrodynamic Laval nozzle. The analogue event horizon, which forms at the nozzle throat is suggested as a novel platform for analogous gravity experiments

Spin resonance induced by a mechanical rotation of a polariton condensate

We study theoretically the polarization dynamics in a ring-shape bosonic condensate of exciton-polaritons confined in a rotating trap. The interplay between the rotating potential and TE-TM splitting of polariton modes offers a tool of control over the spin state and the angular momentum of the condensate. Specific selection rules describing the coupling of pseudospin and angular momentum are formulated. The resonant coupling between states having linear and circular polarizations leads to the polarization beats. The effect may be seen as a polariton analogy to the electronic magnetic resonance in the presence of constant and rotating magnetic fields. Remarkably, spin beats are induced by a purely mechanical rotation of the condensate

Persistent polarization oscillations in ring-shape polariton condensates

We predict the limit cycle solution for a ring-shape bosonic condensate of exciton-polaritons confined in an optically induced rotating trap. The limit cycle manifests itself with polarization oscillations on a characteristic timescale of tens of picoseconds. The effect arises due to the interplay between orbital motion and the polarization degree of freedom. It is specific to spinor bosonic condensates and would be absent in a scalar case, where a bi-stability of stationary solutions would be observed instead. This work offers a tool of initialisation and control of qubits based on superpositions of polariton condensates characterised by different topologic charges