28,172 research outputs found
Quantum coherence of the molecular states and their corresponding currents in nanoscale Aharonov-Bohm interferometers
By considering a nanoscale Aharonov-Bohm (AB) interferometer containing a
parrallel-coupled double dot coupled to the source and drain electrodes, we
investigate the AB phase oscillations of transport current via the bonding and
antibonding state channels. The results we obtained justify the experimental
analysis given in [Phys. Rev. Lett. \textbf{106}, 076801 (2011)] that bonding
state currents in different energy configurations are almost the same. On the
other hand, we extend the analysis to the transient transport current
components flowing through different channels, to explore the effect of the
parity of bonding and antibonding states on the AB phase dependence of the
corresponding current components in the transient regime. The relations of the
AB phase dependence between the quantum states and the associated current
components are analyzed in details, which provides useful information for the
reconstruction of quantum states through the measurement of the transport
current in such systems. With the coherent properties in the quantum dot states
as well as in the transport currents, we also provide a way to manipulate the
bonding and antibonding states by the AB magnetic flux.Comment: 10 pages, 7 figure
Applicability of Relativistic Point-Coupling Models to Neutron Star Physics
Comparing with a wide range of covariant energy density functional models
based on the finite-range meson-exchange representation, the relativistic
mean-field models with the zero-range contact interaction, namely the
relativistic point-coupling models, are still infrequent to be utilized in
establishing nuclear equation of state (EoS) and investigating neutron star
properties, although comprehensive applications and achievements of them in
describing many nuclear properties both in ground and exited states are mature.
In this work, the EoS of neutron star matter is established constructively in
the framework of the relativistic point-coupling models to study neutron star
physics. Taking two selected functionals DD-PC1 and PC-PK1 as examples, nuclear
symmetry energies and several neutron star properties including proton
fractions, mass-radius relations, the core-crust transition density, the
fraction of crustal moment of inertia and dimensionless tidal deformabilities
are discussed. A suppression of pressure of neutron star matter found in the
functional PC-PK1 at high densities results in the difficulty of its prediction
when approaching to the maximum mass of neutron stars. In addition, the
divergences between two selected functionals in describing neutron star
quantities mentioned above are still large, ascribing to the less constrained
behavior of these functionals at high densities. Then it is expected that the
constraints on the dense matter EoS from precise and massive modern
astronomical observations, such as the tidal-deformabilities taken from
gravitational-wave events, would be essential to improve the parameterizing of
the relativistic point-coupling models.Comment: To appear in the AIP Proceedings of the Xiamen-CUSTIPEN Workshop on
the EOS of Dense Neutron-Rich Matter in the Era of Gravitational Wave
Astronomy, Jan. 3-7, Xiamen, Chin
Empirical extinction coefficients for the GALEX, SDSS, 2MASS and WISE passbands
Using the "standard pair" technique of paring stars of almost nil and high
extinction but otherwise of almost identical stellar parameters from the SDSS,
and combing the SDSS, GALEX, 2MASS and WISE photometry ranging from the far UV
to the mid-IR, we have measured dust reddening in the FUV-NUV, NUV-u, u-g, g-r,
r-i, i-z, z-J, J-H, H-Ks, Ks-W1 and W1-W2 colors for thousands of Galactic
stars. The measurements, together with the E(B-V) values given by Schlegel et
al. (1998), allow us to derive the observed, model-free reddening coefficients
for those colors. The results are compared with previous measurements and the
predictions of a variety of Galactic reddening laws. We find that 1) The dust
reddening map of Schlegel et al. (1998) over-estimates E(B-V) by about 14 per
cent, consistent with the recent work of Schlafly et al. (2010) and Schlafly &
Finkbeiner (2011); 2) All the new reddening coefficients, except those for
NUV-u and u-g, prefer the R(V) = 3.1 Fitzpatrick reddening law rather than the
R(V) = 3.1 CCM and O'Donnell (O'Donnell 1994) reddening laws. Using the Ks-band
extinction coefficient predicted by the R(V) = 3.1 Fitzpatrick law and the
observed reddening coefficients, we have deduced new extinction coefficients
for the FUV, NUV, u, g, r, i, z, J, H, W1 and W2 passbands. We recommend that
the new reddening and extinction coefficients should be used in the future and
an update of the Fitzpatrick reddening law in the UV is probably necessary. We
stress however that the FUV- and NUV-band coefficients should be used with
caution given their relatively large measurement uncertainties. Finally,
potential applications of the "standard pair" technique with the LAMOST
Galactic surveys are discussed.Comment: 13 pages, 9 figures, accepted to MNRA
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