Quantum noise in the spin transfer torque effect

Describing the microscopic details of the interaction of magnets and spin-polarized currents is key to achieve control of such systems at the microscopic level. Here we discuss a description based on the Keldysh technique, casting the problem in the language of open quantum systems. We reveal the origin of noise in the presence of both field-like and damping like terms in the equation of motion arising from spin conductance

Nonlinear Inverse Spin Galvanic Effect in Anisotropic Disorder-free Systems

Spin transport phenomena in solid materials suffer limitations from spin relaxation associated to disorder or lack of translational invariance. Ultracold atoms, free of that disorder, can provide a platform to observe phenomena beyond the usual two-dimensional electron gas. By generalizing the approach used for isotropic two-dimensional electron gases, we theoretically investigate the inverse spin galvanic effect in the two-level atomic system in the presence of anisotropic Rashba-Dresselhaus spin-orbit couplings (SOC) and external magnetic field. We show that the combination of the SOC results in an asymmetric case: the total spin polarization considered for a small momentum has a longer spin state than in a two-dimensional electron gas when the SOC field prevails over the external electric field. Our results can be relevant for advancing experimental and theoretical investigations in spin dynamics as a basic approach for studying spin state control

Intrinsic spin Hall effect in systems with striped spin-orbit coupling

The Rashba spin-orbit coupling arising from structure inversion asymmetry couples spin and momentum degrees of freedom providing a suitable (and very intensively investigated) environment for spintronic effects and devices. Here we show that in the presence of strong disorder, non-homogeneity in the spin-orbit coupling gives rise to a finite spin Hall conductivity in contrast with the corresponding case of a homogeneous linear spin-orbit coupling. In particular, we examine the inhomogeneity arising from a striped structure for a two-dimensional electron gas, affecting both density and Rashba spin-orbit coupling. We suggest that this situation can be realized at oxide interfaces with periodic top gating.Comment: 9 pages, 8 figure

Bridging thermodynamics and metrology in non-equilibrium Quantum Thermometry

Single-qubit thermometry presents the simplest tool to measure the temperature of thermal baths with reduced invasivity. At thermal equilibrium, the temperature uncertainty is linked to the heat capacity of the qubit, however the best precision is achieved outside equilibrium condition. Here, we discuss a way to generalize this relation in a non-equilibrium regime, taking into account purely quantum effects such as coherence. We support our findings with an experimental photonic simulation.Comment: 7 pages, 4 figure

Design and manufacture of hybrid aluminum/composite co-cured tubes with viscoelastic interface layer

Abstract The development of hybrid FRP-metal axisymmetric components is a matter of increasing interest in the automotive and aerospace industry for a lightweight design. The hybridization of the technology enables a cost reduction of components production and an increase of mechanical performances together with the ability of machining the surface of the metal tube; this technique guarantees a production improvement since the coating of the tube is no longer required and the pieces can be manufactured in one-step curing cycle. The improvement in bending and torsional stiffness, corrosion resistance and mass reduction of hybrid tubes, in comparison to the single material-built component, has been already demonstrated. A great challenge is to find a way to make hybrid tubes with external metal, avoiding delaminations and detachments that could occur during and after the curing process, due to the different coefficients of thermal expansion between FRP and metal along the axial direction of the tube. For this reason, a component manufacturing process has been studied by experimental and numerical analysis (FEM), including custom process machines and inserting a viscoelastic layer as an interface between the two tubes. Genetic algorithm method has been used to optimize the stacking sequence of a hybrid co-cured metal/composite tube to maximize the flexural stiffness, while applying a strength constraint condition