268 research outputs found
Time-dependent simulation and analytical modelling of electronic Mach-Zehnder interferometry with edge-states wave packets
We compute the exact single-particle time-resolved dynamics of electronic
Mach-Zehnder interferometers based on Landau edge-states transport, and assess
the effect of the spatial localization of carriers on the interference pattern.
The exact carrier dynamics is obtained by solving numerically the
time-dependent Schroedinger equation with a suitable 2D potential profile
reproducing the interferometer design. An external magnetic field, driving the
system to the quantum Hall regime with filling factor one, is included. The
injected carriers are represented by a superposition of edge states and their
interference pattern reproduces the results of Y.Ji et al.[Nature 422, 415
(2003)]. By tuning the system towards different regimes, we find two additional
features in the transmission spectra, both related to carrier localization,
namely a damping of the Aharonov-Bohm oscillations with increasing difference
in the arms length, and an increased mean transmission that we trace to the
energy-dependent transmittance of quantum point contacts. Finally, we present
an analytical model, also accounting for the finite spatial dispersion of the
carriers, able to reproduce the above effects.Comment: two-columns, 12 pages, 9 figures; added 10 refs.; main text modified;
corrected few typos; added 3 figures of Supplementary Dat
Analytical expression of Genuine Tripartite Quantum Discord for Symmetrical X-states
The study of classical and quantum correlations in bipartite and multipartite
systems is crucial for the development of quantum information theory. Among the
quantifiers adopted in tripartite systems, the genuine tripartite quantum
discord (GTQD), estimating the amount of quantum correlations shared among all
the subsystems, plays a key role since it represents the natural extension of
quantum discord used in bipartite systems. In this paper, we derive an
analytical expression of GTQD for three-qubit systems characterized by a
subclass of symmetrical X-states. Our approach has been tested on both GHZ and
maximally mixed states reproducing the expected results. Furthermore, we
believe that the procedure here developed constitutes a valid guideline to
investigate quantum correlations in form of discord in more general
multipartite systems.Comment: 13 pages, 4 figures. v3: Added some references and corrected some
typo
Entanglement creation in semiconductor quantum dot charge qubit
We study theoretically the appearance of quantum correlations in two- and
three-electron scattering in single and double dots. The key role played by
transport resonances into entanglement formation between the single-particle
states is shown. Both reflected and transmitted components of the scattered
particle wavefunction are used to evaluate the quantum correlations between the
incident carrier and the bound particle(s) in the dots. Our investigation
provides a guideline for the analysis of decoherence effects due to the Coulomb
scattering in semiconductor quantum dots structures.Comment: 8 pages, 5 figures, Proceedings of Quantum 2010:24-28, May, 2010
Torin
Magneto-photoluminescence in GaAs/AlAs core-multishell nanowires: a theoretical investigation
The magneto-photoluminescence in modulation doped core-multishell nanowires
is predicted as a function of photo-excitation intensity in non-perturbative
transverse magnetic fields. We use a self-consistent field approach within the
effective mass approximation to determine the photoexcited electron and hole
populations, including the complex composition and anisotropic geometry of the
nano-material. The evolution of the photoluminescence is analyzed as a function
of i) photo-excitation power, ii) magnetic field intensity, iii) type of
doping, and iv) anisotropy with respect to field orientation.Comment: 11 pages, 11 figures, accepted for publication in Physical Review
Quantum correlations of identical particles subject to classical environmental noise
Abstract In this work, we propose a measure for the quantum discord of indistinguishable
particles, based on the definition of entanglement of particles given in
Wiseman and Vaccaro (Phys Rev Lett 91:097902, 2003. doi:10.1103/PhysRevLett.91.
097902). This discord of particles is then used to evaluate the quantum correlations in
a system of two identical bosons (fermions), where the particles perform a quantum
random walk described by the Hubbard Hamiltonian in a 1D lattice. The dynamics of
the particles is either unperturbed or subject to a classical environmental noise—such
as random telegraph, pink or brown noise. The observed results are consistent with
those for the entanglement of particles, and we observe that on-site interaction between
particles have an important protective effect on correlations against the decoherence
of the system
Linear entropy as an entanglement measure in two-fermion systems
We describe an efficient theoretical criterion, suitable for
indistinguishable particles to quantify the quantum correlations of any pure
two-fermion state, based on the Slater rank concept. It represents the natural
generalization of the linear entropy used to treat quantum entanglement in
systems of non-identical particles. Such a criterion is here applied to an
electron-electron scattering in a two-dimensional system in order to perform a
quantitative evaluation of the entanglement dynamics for various spin
configurations and to compare the linear entropy with alternative approaches.
Our numerical results show the dependence of the entanglement evolution upon
the initial state of the system and its spin components. The differences with
previous analyses accomplished by using the von Neumann entropy are discussed.
The evaluation of the entanglement dynamics in terms of the linear entropy
results to be much less demanding from the computational point of view, not
requiring the diagonalization of the density matrix.Comment: 16 pages. Added references in section 1 Corrected typo
Quantum teleportation of electrons in quantum wires with surface acoustic waves
We propose and numerically simulate a semiconductor device based on coupled
quantum wires, suitable for deterministic quantum teleportation of electrons
trapped in the minima of surface acoustic waves.We exploit a network of
interacting semiconductor quantum wires able to provide the universal set of
gates for quantum information processing, with the qubit defined by the
localization of a single electron in one of two coupled channels.The numerical
approach is based on a time-dependent solution of the three-particle
Schr\"odinger equation. First, a maximally entangled pair of electrons is
obtained via Coulomb interaction between carriers in different channels. Then,
a complete Bell-state measurement involving one electron from this pair and a
third electron is performed. Finally, the teleported state is reconstructed by
means of local one-qubit operations. The large estimated fidelity explicitely
suggests that an efficient teleportation process could be reached in an
experimental setup.Comment: 7 pages,4 figures, 1 tabl
AN ANTI-STRESS PROTOCOL BASED ON THE PSYCHOLOGICAL FUNCTIONAL MODEL
ABSTRACT In psychology, Functional Model considers the individual as a unity and at the same time in all its complexity, i.e. analyzes the single psychosomatic individual functions, without losing sight the global view of the person. This paper proposes an anti-stress protocol capable to improve the quality of life in an environmentally correct manner
Carrier-carrier entanglement and transport resonances in semiconductor quantum dots
We study theoretically the entanglement created in a scattering between an
electron, incoming from a source lead, and another electron bound in the ground
state of a quantum dot, connected to two leads. We analyze the role played by
the different kinds of resonances in the transmission spectra and by the number
of scattering channels, into the amount of quantum correlations between the two
identical carriers. It is shown that the entanglement between their energy
states is not sensitive to the presence of Breit-Wigner resonances, while it
presents a peculiar behavior in correspondence of Fano peaks: two close maxima
separated by a minimum, for a two-channel scattering, a single maximum for a
multi-channel scattering. Such a behavior is ascribed to the different
mechanisms characterizing the two types of resonances. Our results suggest that
the production and detection of entanglement in quantum dot structures may be
controlled by the manipulation of Fano resonances through external fields.Comment: 8 pages, 6 figures, RevTex4 two-column format, submitte
Fluorinated heterocyclic compounds. A photochemical approach to a synthesis of polyfluoroaryl-1,2,4-triazoles
The reaction of some fluorinated 1,2,4-oxadiazoles in the presence of methylamine or propylamine has been investigated. The irradiation in methanol or acetonitrile leads with acceptable yields to the corresponding fluorinated 1-methyl- or 1-propyl-1,2,4-triazole
- …