Paul-Antoine Hervieux

Autoresonant control of the many-electron dynamics in nonparabolic quantum wells

The optical response of nonparabolic quantum wells is dominated by a strong peak at the plasmon frequency. When the electrons reach the anharmonic regions, resonant absorption becomes inefficient. This limitation is overcome by using a chirped laser pulse in the autoresonant regime. By direct simulations using the Wigner phase-space approach, the authors prove that, with a sequence of just a few pulses, electrons can be efficiently detrapped from a nonparabolic well. For an array of multiple quantum wells, they can create and control an electronic current by suitably applying an autoresonant laser pulse and a slowly varying dc electric field.

Breather mode in the many-electron dynamics of semiconductor quantum wells

We demonstrate the existence of a breather mode in the self-consistent electron dynamics of a semiconductor quantum well. A nonperturbative variational method based on quantum hydrodynamics is used to determine the salient features of the electron breather mode. Numerical simulations of the time-dependent Wigner-Poisson or Hartree equations are shown to be in excellent agreement with our analytical results. For asymmetric quantum wells, a signature of the breather mode is observed in the dipole response, which can be detected by standard optical means.

Semiclassical Vlasov and fluid models for an electron gas with spin effects

We derive a four-component Vlasov equation for a system composed of spin-1/2 fermions (typically electrons). The orbital part of the motion is classical, whereas the spin degrees of freedom are treated in a completely quantum-mechanical way. The corresponding hydrodynamic equations are derived by taking velocity moments of the phase-space distribution function. This hydrodynamic model is closed using a maximum entropy principle in the case of three or four constraints on the fluid moments, both for Maxwell-Boltzmann and Fermi-Dirac statistics.

Variational approach to the time-dependent Schrödinger–Newton equations

Using a variational approach based on a Lagrangian formulation and Gaussian trial functions, we derive a simple dynamical system that captures the main features of the time-dependent Schrodinger-Newton equations. With little analytical or numerical effort, the model furnishes information on the ground state density and energy eigenvalue, the linear frequencies, as well as the nonlinear long-time behaviour. Our results are in good agreement with those obtained through analytical estimates or numerical simulations of the full Schrodinger-Newton equations.

Autoresonant control of the magnetization switching in single-domain nanoparticles

The ability to control the magnetization switching in nanoscale devices is a crucial step for the development of fast and reliable techniques to store and process information. Here we show that the switching dynamics can be controlled efficiently using a microwave field with slowly varying frequency (autoresonance). This technique allowed us to reduce the applied field by more than

Lagrangian approach to the semirelativistic electron dynamics in the mean-field approximation

30%

Ultrafast magnetization dynamics in diluted magnetic semiconductors

compared to competing approaches, with no need to fine-tune the field parameters. For a linear chain of nanoparticles the effect is even more dramatic, as the dipolar interactions tend to cancel out the effect of the temperature. Simultaneous switching of all the magnetic moments can thus be efficiently triggered on a nanosecond timescale.

Quantum–classical transition in the electron dynamics of thin metal films

We derive a mean-field model that is based on a two-component Pauli-like equation and incorporates quantum, spin, and relativistic effects up to second order in

Ab initio calculation of differential cross sections for the double ionization of water vapour by electron impact

1/c

Exact treatment of planar two-electron quantum dots: Effects of anharmonicity on the complexity

. Using a Lagrangian approach, we obtain the self-consistent charge and current densities that act as sources in the Maxwell equations. A physical interpretation is provided for the second-order corrections to the sources. The Maxwell equations are also expanded to the same order. The resulting self-consistent model constitutes a suitable semi-relativistic approximation to the full Dirac-Maxwell equations.