15,136 research outputs found
Protected Rabi oscillation induced by natural interactions among physical qubits
For a system composed of nine qubits, we show that natural interactions among
the qubits induce the time evolution that can be regarded, at discrete times,
as the Rabi oscillation of a logical qubit. Neither fine tuning of the
parameters nor switching of the interactions is necessary. Although
straightforward application of quantum error correction fails, we propose a
protocol by which the logical Rabi oscillation is protected against all
single-qubit errors. The present method thus opens a simple and realistic way
of protecting the unitary time evolution against noise.Comment: In this revised manuscript, new sections V, VI, VII and new
appendices A, B, C have been added to give detailed discussions. 13 pages, 4
figure
Photoluminescence and spectral switching of single CdSe/ZnS colloidal nanocrystals in poly(methyl methacrylate)
Emission from single CdSe nanocrystals in PMMA was investigated. A fraction
of the nanocrystals exhibiting switching between two energy states, which have
similar total intensities, but distinctly different spectra were observed. We
found that the spectral shift characteristic frequency increases with the pump
power. By using the dynamic shift in the spectral position of emission peaks,
we were able to correlate peaks from the same nanocrystal. The measured
correlation is consistent with assignment of low energy lines to phonon
replicas.Comment: 5 pages, 4 figure
The small-scale structure of photospheric convection retrieved by a deconvolution technique applied to Hinode/SP data
Solar granules are bright patterns surrounded by dark channels called
intergranular lanes in the solar photosphere and are a manifestation of
overshooting convection. Observational studies generally find stronger upflows
in granules and weaker downflows in intergranular lanes. This trend is,
however, inconsistent with the results of numerical simulations in which
downflows are stronger than upflows through the joint action of gravitational
acceleration/deceleration and pressure gradients. One cause of this discrepancy
is the image degradation caused by optical distortion and light diffraction and
scattering that takes place in an imaging instrument. We apply a deconvolution
technique to Hinode/SP data in an attempt to recover the original solar scene.
Our results show a significant enhancement in both, the convective upflows and
downflows, but particularly for the latter. After deconvolution, the up- and
downflows reach maximum amplitudes of -3.0 km/s and +3.0 km/s at an average
geometrical height of roughly 50 km, respectively. We found that the velocity
distributions after deconvolution match those derived from numerical
simulations. After deconvolution the net LOS velocity averaged over the whole
FOV lies close to zero as expected in a rough sense from mass balance.Comment: 32 pages, 13 figures, accepted for publication in Ap
Shape coexistence in Lead isotopes in the interacting boson model with Gogny energy density functional
We investigate the emergence and evolution of shape coexistence in the
neutron-deficient Lead isotopes within the interacting boson model (IBM) plus
configuration mixing with microscopic input based on the Gogny energy density
functional (EDF). The microscopic potential energy surface obtained from the
constrained self-consistent Hartree-Fock-Bogoliubov method employing the
Gogny-D1M EDF is mapped onto the coherent-state expectation value of the
configuration-mixing IBM Hamiltonian. In this way, the parameters of the IBM
Hamiltonian are fixed for each of the three relevant configurations (spherical,
prolate and oblate) associated to the mean field minima. Subsequent
diagonalization of the Hamiltonian provides the excitation energy of the
low-lying states and transition strengths among them. The model predictions for
the level energies and evolving shape coexistence in the considered
Lead chain are consistent both with experiment and with the indications of the
Gogny-EDF energy surfaces.Comment: 12 pages, 6 figures, 1 tabl
1D Modeling for Temperature-Dependent Upflow in the Dimming Region Observed by Hinode/EIS
We have previously found a temperature-dependent upflow in the dimming region
following a coronal mass ejection (CME) observed by the {\it Hinode} EUV
Imaging Spectrometer (EIS). In this paper, we reanalyzed the observations along
with previous work on this event, and provided boundary conditions for
modeling. We found that the intensity in the dimming region dramatically drops
within 30 minutes from the flare onset, and the dimming region reaches the
equilibrium stage after 1 hour later. The temperature-dependent upflows
were observed during the equilibrium stage by EIS. The cross sectional area of
the fluxtube in the dimming region does not appear to expand significantly.
From the observational constraints, we reconstructed the temperature-dependent
upflow by using a new method which considers the mass and momentum conservation
law, and demonstrated the height variation of plasma conditions in the dimming
region. We found that a super radial expansion of the cross sectional area is
required to satisfy the mass conservation and momentum equations. There is a
steep temperature and velocity gradient of around 7 Mm from the solar surface.
This result may suggest that the strong heating occurred above 7 Mm from the
solar surface in the dimming region. We also showed that the ionization
equilibrium assumption in the dimming region is violated especially in the
higher temperature range.Comment: accepted for publication in The Astrophysical Journa
The Brieva-Rook Localization of the Microscopic Nucleon-Nucleus Potential
The nonlocality of the microscopic nucleon-nucleus optical potential is
commonly localized by the Brieva-Rook approximation. The validity of the
localization is tested for the proton+Zr scattering at the incident
energies from 65 MeV to 800 MeV. The localization is valid in the wide
incident-energy range.Comment: 20 pages, 8 figure
Drop on a Bent Fibre
Inspired by the huge droplets attached on cypress tree leaf tips after rain,
we find that a bent fibre can hold significantly more water in the corner than
a horizontally placed fibre (typically up to three times or more). The maximum
volume of the liquid that can be trapped is remarkably affected by the bending
angle of the fibre and surface tension of the liquid. We experimentally find
the optimal included angle () that holds the most water.
Analytical and semi-empirical models are developed to explain these
counter-intuitive experimental observations and predict the optimal angle. The
data and models could be useful for designing microfluidic and fog harvesting
devices
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