Teleportation between distant qudits via scattering of mobile qubits

We consider a one-dimensional (1D) structure where non-interacting spin-$s$ scattering centers, such as quantum impurities or multi-level atoms, are embedded at given positions. We show that the injection into the structure of unpolarized flying qubits, such as electrons or photons, along with {path} detection suffice to accomplish spin-state teleportation between two centers via a third ancillary one. {No action over the internal quantum state of both the spin-$s$ particles and the flying qubits is required. The protocol enables the transfer of quantum information between well-seperated static entities in nanostructures by exploiting a very low-control mechanism, namely scattering.Comment: 8 pages, 5 figure

Electron interactions with atoms in intense electromagnetic fields

In the first part of the thesis we consider two theoretical problems: (a) The Kroll-Watson result for laser assisted potential scattering of charged particle has been extended to the case where a uniform static magnetic field is also present, and the consequences examined. (b) The problem of the transition of an incoming plane wave state of a charged particle entering such a magnetic field, to occupy Landau levels is solved in both the adiabatic and the sudden cases. The cross section for potential scattering in presence of a magnetic field and the limit for B0 are derived. The second part of the thesis deals with laser assisted electron impact ionisation of helium atoms. The slow electron is described in a tree-state close-coupling formulation. Conditions for the observation of the predicted splitting of the "Erhardt" pattern of the triple differential cross section are discussed.<p

Entanglement-induced electron coherence in a mesoscopic ring with two magnetic impurities

We investigate the Aharonov-Bohm (AB) interference pattern in the electron transmission through a mesoscopic ring in which two identical non-interacting magnetic impurities are embedded. Adopting a quantum waveguide theory, we derive the exact transmission probability amplitudes and study the influence of maximally entangled states of the impurity spins on the electron transmittivity interference pattern. For suitable electron wave vectors, we show that the amplitude of AB oscillations in the absence of impurities is in fact not reduced within a wide range of the electron-impurity coupling constant when the maximally entangled singlet state is prepared. Such state is thus able to inhibit the usual electron decoherence due to scattering by magnetic impurities. We also show how this maximally entangled state of the impurity spins can be generated via electron scattering.Comment: 8 page

Diffusion of neutrons by a slab of moderating material: an application of the Monte Carlo Method

An application of the Monte Carlo method to the diffusion of neutrons passing through a slab of a moderating material is presented. This method can be used as a tool to improve the student's comprehension of the statistical properties of many particle systems, showing the necessity of simulation procedures to obtain information on the expected results of real experiments. We have chosen a very simple example to illustrate it: the evaluation of the transmission, reflection and absorption probabilities of a monochromatic beam of neutrons diffusing through a slab of a moderator material. After a collision with a nucleus of the moderator the neutron may be either elastically scattered or captured. The transmission, reflection and absorption properties of the neutrons diffused by different moderating materials are visualized with the help of an appropriate animation progra

Third harmonic generation in the skin layer of a hot dense plasma

The third harmonic generation of a pump wave, resulting from the electron-ion collision frequency dependence on the electric field in the skin-layer of a hot dense plasma is investigated. The relation of the current third harmonic with the high-frequency field in the skin-layer is established for arbitrary ratios of the electron-ion collision frequency to the field frequency. For arbitrary ratios of these two frequencies the field structure inside the skin-layer is determined, and the field of the wave irradiated by the plasma at tripled frequency too is calculated. It has permitted to find the explicit dependencies of the third harmonic generation efficiency on the plasma and pump fiel