Quantum-state transfer via resonant tunnelling through local field induced barriers

Efficient quantum-state transfer is achieved in a uniformly coupled spin-1/2 chain, with open boundaries, by application of local magnetic fields on the second and last-but-one spins, respectively. These effective \textit{barriers} induce appearance of two eigenstates, bi-localized at the edges of the chain, which allow a high quality transfer also at relatively long distances. The same mechanism may be used to send an entire e-bit (e.g., an entangled qubit pair) from one to the other end of the chain

Decoherence in a fermion environment: Non-Markovianity and Orthogonality Catastrophe

We analyze the non-Markovian character of the dynamics of an open two-level atom interacting with a gas of ultra-cold fermions. In particular, we discuss the connection between the phenomena of orthogonality catastrophe and Fermi edge singularity occurring in such a kind of environment and the memory-keeping effects which are displayed in the time evolution of the open system

Low dose of Rotigotine in post-stroke patients with vascular parkinsonism and obstructive sleep apnoea syndrome, effects on quality of life and rehabilitation therapy

Stroke is a frequent cause of disability in U.S.A. (200.000/ year). Aim: The aim of this study is to underline the effect of low dose of Rotigotine patches 2 mg/24 h, a complete dopamine agonist with continuous dopaminergic stimulation through the transdermal administration, in elderly with recent stroke and vascular Parkinsonism about quality of life and adherence to rehabilitation therapy. Methods: We have enrolled 6 elderly patients (3 males and 3 females, range age 60 – 95 years) with recent ischemic and vascular Parkinsonism. We have evaluated quality of life and cognitive function with UPDRS part III, MMSE, ADL, IADL and Morinsky Scale. At the same time we have evaluated the adherence to therapy and timing of rehabilitation therapy before and post-administration of Rotigotine 2 mg/24 hours. Conclusion: In conclusion, Rotigotine could be a new useful approach in the treatment of elderly patients with recent ischemic and hemorrhagic stroke correlated with vascular Parkinsonism which can lead to an akinesia with the need to start rehabilitation therapy. Our preliminary data gives comfortable results but, at this time, we have enrolled only few patients to give conclusive results

Acoustic plasmons in extrinsic free-standing graphene

Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.An acoustic plasmon is predicted to occur, in addition to the conventional two-dimensional (2D) plasmon, as the collective motion of a system of two types of electronic carriers coexisting in the same 2D band of extrinsic (doped or gated) graphene. The origin of this novel mode stems from the anisotropy present in the graphene band structure near the Dirac points K and K'. This anisotropy allows for the coexistence of carriers moving with two distinct Fermi velocities along the γK and γK' directions, which leads to two modes of collective oscillation: one mode in which the two types of carriers oscillate in phase with one another (this is the conventional 2D graphene plasmon, which at long wavelengths (q → 0) has the same dispersion, q1/2, as the conventional 2D plasmon of a 2D free electron gas), and the other mode found here corresponds to a low-frequency acoustic oscillation (whose energy exhibits at long-wavelengths a linear dependence on the 2D wavenumber q) in which the two types of carriers oscillate out of phase. This prediction represents a realization of acoustic plasmons originated in the collective motion of a system of two types of carriers coexisting within the same band. © 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.MP acknowledges the financial support of MIUR (FIRB-Futuro in Ricerca 2010—Project PLASMOGRAPH grant no. RBFR10M5BT), the European Commission, the European Social Fund and Regione Calabria, (POR) Calabria—FSE 2007/2013. VMS acknowledges financial support from the Spanish MICINN (no. FIS2010-19609-C02-01), the Departamento de Educación del Gobierno Vasco, and the University of the Basque Country (no. GIC07-IT-366-07).Peer Reviewe

Dielectric screening and plasmon resonances in bilayer graphene

The plasmon structure of intrinsic and extrinsic bilayer graphene is investigated in the framework of ab initio time-dependent density-functional theory (TDDFT) at the level of the random-phase approximation (RPA). A two-step scheme is adopted, where the electronic ground state of a periodically repeated slab of bilayer graphene is first determined with full inclusion of the anisotropic band structure and the interlayer interaction; a Dyson-like equation is then solved self-consistently in order to calculate the so-called density-response function of the many-electron system. A two-dimensional correction is subsequently applied in order to eliminate the artificial interaction between the replicas. The energy range below ∼30 eV is explored, focusing on the spectrum of single-particle excitations and plasmon resonances induced by external electrons or photons. The high-energy loss features of the π and σ+π plasmons, particularly their anisotropic dispersions, are predicted and discussed in relation with previous calculations and experiments performed on monolayer and bilayer graphene. At the low-energy end, the energy-loss function is found to be (i) very sensitive to the injected charge carrier density in doped bilayer graphene and (ii) highly anisotropic. Furthermore, various plasmon modes are predicted to exist and are analyzed with reference to the design of novel nanodevicesM.P. and M.G. acknowledge financial support by the European Commission, the European Social Fund, and the Regione Calabria, (POR) Calabria - FSE 2007/2013, and the hospitality of CIC nanoGUNE and the Donostia International Physics Center (DIPC). V.M.S. acknowledges the partial support from the Basque Departamento de Educación, UPV/EHU (Grant No. IT-756-13) and the Spanish Ministry of Economy and Competitiveness MINECO (Grant No. FIS2013-48286-C2-1-P

The role of atomic collisions in kinetic electron emission from Al surfaces by slow ions

Abstract We measured energy distributions of electrons emitted in the interaction of slow Kr + and Na + with Al surfaces. The data allow to correlate emission intensities with spectral signatures of electron excitation processes. Our results indicate that electron promotion processes leading to the excitation of Al target atoms plays the dominating role in kinetic electron emission from Al surfaces by slow ions. In the case of Kr + ions, electron promotion occurs in close atomic collisions between recoiling target atoms. For Na + projectiles, a significant contribution to Al excitation comes also from a vacancy transfer process in asymmetric collisions involving ions that have survived neutralization in the interaction with the surface