63 research outputs found
Shape transitions in excited states of two-electron quantum dots in a magnetic field
We use entanglement to study shape transitions in two-electron axially symmetric parabolic quantum dots in a perpendicular magnetic field. At a specific magnetic field value the dot attains a spherical symmetry. The transition from the axial to the spherical symmetry manifests itself as a drastic change of the entanglement of the lowest state with zero angular momentum projection. While the electrons in such a state are always localized in the plane (x-y) before the transition point, after this point they become localized in the vertical direction.Fil: Nazmitdinov, R.G.. Bogoliubov Laboratory Of Theoretical Physics, Joint Institute For Nuclear Research; Rusia. Universitat de Les Illes Balears; EspañaFil: Simonovic, N. S.. University of Belgrade; SerbiaFil: Plastino, Ángel Ricardo. Comisión de Regulación de Energía y Gas; Argentina. Universidad Nacional de La Plata; Argentina. Universidad de Granada; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Chizhov, A.V.. Bogoliubov Laboratory Of Theoretical Physics, Joint Institute For Nuclear Research; Rusi
Wobbling excitations at high spins in A~160
We found that in 156Dy and 162Yb the lowest odd spin gamma-vibrational states
transform to the wobbling excitations after the backbending, associated with
the transition from axially-symmetric to nonaxial shapes. The analysis of
quadrupole electric transitions determines uniquely the sign of the
gamma-deformation in both nuclei after the transition point.Comment: 6 pages, 4 figure
Dynamics of open quantum systems
The coupling between the states of a system and the continuum into which it
is embedded, induces correlations that are especially large in the short time
scale. These correlations cannot be calculated by using a statistical or
perturbational approach. They are, however, involved in an approach describing
structure and reaction aspects in a unified manner. Such a model is the SMEC
(shell model embedded in the continuum). Some characteristic results obtained
from SMEC as well as some aspects of the correlations induced by the coupling
to the continuum are discussed.Comment: 16 pages, 5 figure
Conformal Hamiltonian Dynamics of General Relativity
The General Relativity formulated with the aid of the spin connection
coefficients is considered in the finite space geometry of similarity with the
Dirac scalar dilaton. We show that the redshift evolution of the General
Relativity describes the vacuum creation of the matter in the empty Universe at
the electroweak epoch and the dilaton vacuum energy plays a role of the dark
energy.Comment: 9 pages, 1 figure, submitted to PL
Hidden symmetries of two-electron quantum dots in a magnetic field
Using a classical and quantum mechanical analysis, we show that the magnetic
field gives rise to dynamical symmetries of a three-dimensional axially
symmetric two-electron quantum dot with a parabolic confinement. These
symmetries manifest themselves as near-degeneracies in the quantum spectrum at
specific values of the magnetic field and are robust at any strength of the
electron-electron interaction.Comment: 6 pages, 3 figures in a gif forma
Resonance scattering and singularities of the scattering function
Recent studies of transport phenomena with complex potentials are explained
by generic square root singularities of spectrum and eigenfunctions of
non-Hermitian Hamiltonians. Using a two channel problem we demonstrate that
such singularities produce a significant effect upon the pole behaviour of the
scattering matrix, and more significantly upon the associated residues. This
mechanism explains why by proper choice of the system parameters the resonance
cross section is increased drastically in one channel and suppressed in the
other channel.Comment: 4 pages, 3 figure
Scanning Fourier Spectroscopy: A microwave analog study to image transmission paths in quantum dots
We use a microwave cavity to investigate the influence of a movable absorbing
center on the wave function of an open quantum dot. Our study shows that the
absorber acts as a position-selective probe, which may be used to suppress
those wave function states that exhibit an enhancement of their probability
density near the region where the impurity is located. For an experimental
probe of this wave function selection, we develop a technique that we refer to
as scanning Fourier spectroscopy, which allows us to identify, and map out, the
structure of the classical trajectories that are important for transmission
through the cavity.Comment: 4 pages, 5 figure
Nuclear matter at high density: Phase transitions, multiquark states, and supernova outbursts
Phase transition from hadronic matter to quark-gluon matter is discussed for
various regimes of temperature and baryon number density. For small and medium
densities, the phase transition is accurately described in the framework of the
Field Correlation Method, whereas at high density predictions are less certain
and leave room for the phenomenological models. We study formation of
multiquark states (MQS) at zero temperature and high density. Relevant MQS
components of the nuclear matter can be described using a previously developed
formalism of the quark compound bags (QCB).
Partial-wave analysis of nucleon-nucleon scattering indicates the existence
of 6QS which manifest themselves as poles of -matrix. In the framework of
the QCB model, we formulate a self-consistent system of coupled equations for
the nucleon and 6QS propagators in nuclear matter and the G-matrix. The
approach provides a link between high-density nuclear matter with the MQS
components and the cumulative effect observed in reactions on the nuclei, which
requires the admixture of MQS in the wave functions of nuclei kinematically.
6QS determine the natural scale of the density for a possible phase
transition into the MQS phase of nuclear matter. Such a phase transition can
lead to dynamic instability of newly born protoneutron stars and dramatically
affect the dynamics of supernovae. Numerical simulations show that the phase
transition may be a good remedy for the triggering supernova explosions in the
spherically symmetric supernova models. A specific signature of the phase
transition is an additional neutrino peak in the neutrino light curve. For a
Galactic core-collapse supernova, such a peak could be resolved by the present
neutrino detectors. The possibility of extracting the parameters of the phase
of transition from observation of the neutrino signal is discussed also.Comment: 57 pages, 22 figures, 7 tables; RevTeX 4; submitted to Phys. Atom.
Nuc
- …