13,561 research outputs found
Quantum gate using qubit states separated by terahertz
A two-qubit quantum gate is realized using electronic excited states in a
single ion with an energy separation on the order of a terahertz times the
Planck constant as a qubit. Two phase locked lasers are used to excite a
stimulated Raman transition between two metastable states and
separated by 1.82 THz in a single trapped Ca ion to
construct a qubit, which is used as the target bit for the Cirac-Zoller
two-qubit controlled NOT gate. Quantum dynamics conditioned on a motional qubit
is clearly observed as a fringe reversal in Ramsey interferometry.Comment: 4 pages, 4 figure
Signatures of S-wave bound-state formation in finite volume
We discuss formation of an S-wave bound-state in finite volume on the basis
of L\"uscher's phase-shift formula.It is found that although a bound-state pole
condition is fulfilled only in the infinite volume limit, its modification by
the finite size corrections is exponentially suppressed by the spatial extent
in a finite box . We also confirm that the appearance of the S-wave
bound state is accompanied by an abrupt sign change of the S-wave scattering
length even in finite volume through numerical simulations. This distinctive
behavior may help us to discriminate the loosely bound state from the lowest
energy level of the scattering state in finite volume simulations.Comment: 25 pages, 30 figures; v2: typos corrected and two references added,
v3: final version to appear in PR
Recombining Plasma & Gamma-ray Emission in the Mixed-morphology Supernova Remnant 3C 400.2
3C 400.2 belongs to the mixed morphology supernova remnant class, showing
center-filled X-ray and shell-like radio morphology. We present a study of 3C
400.2 with archival Suzaku and Fermi-LAT observations. We find recombining
plasma (RP) in the Suzaku spectra of north-east and south-east regions. The
spectra of these regions are well described by two-component thermal plasma
models: The hard component is in RP, while the soft component is in collisional
ionization equilibrium (CIE) conditions. The RP has enhanced abundances
indicating that the X-ray emission has an ejecta origin, while the CIE has
solar abundances associated with the interstellar material. The X-ray spectra
of north-west and south-west regions are best fitted by a two-component thermal
plasma model: an ionizing and a CIE plasma. We have detected GeV gamma-ray
emission from 3C 400.2 at the level of 5 assuming a point-like
source model with a power-law (PL) type spectrum. We have also detected a new
GeV source at the level of 13 assuming a Gaussian extension model
with a PL type spectrum in the neighborhood of the SNR. We report the analysis
results of 3C 400.2 and the new extended gamma-ray source and discuss the
nature of gamma-ray emission of 3C 400.2 in the context of existing NANTEN CO
data, DRAO HI data, and the Suzaku X-ray analysis results.Comment: Accepted to be published in the Astrophysical Journa
The relation between post-shock temperature, cosmic-ray pressure and cosmic-ray escape for non-relativistic shocks
Supernova remnants are thought to be the dominant source of Galactic cosmic
rays. This requires that at least 5% of the available energy is transferred to
cosmic rays, implying a high cosmic-ray pressure downstream of supernova
remnant shocks. Recently, it has been shown that the downstream temperature in
some remnants is low compared to the measured shock velocities, implying that
additional pressure support by accelerated particles is present.
Here we use a two-fluid thermodynamic approach to derive the relation between
post-shock fractional cosmic-ray pressure and post-shock temperature, assuming
no additional heating beyond adiabatic heating in the shock precursor and with
all non-adiabatic heating occurring at the subshock. The derived relations show
that a high fractional cosmic-ray pressure is only possible, if a substantial
fraction of the incoming energy flux escapes from the system. Recently a shock
velocity and a downstream proton temperature were measured for a shock in the
supernova remnant RCW 86. We apply the two-fluid solutions to these
measurements and find that the the downstream fractional cosmic-ray pressure is
at least 50% with a cosmic-ray energy flux escape of at least 20%. In general,
in order to have 5% of the supernova energy go into accelerating cosmic rays,
on average the post-shock cosmic-ray pressure needs to be 30% for an effective
cosmic-ray adiabatic index of 4/3.Comment: 9 pages, 6 color figures. This is updated with a corrected figure 5a
and 5b, reflecting an ApJ erratu
Kaonic nuclei studied based on a new framework of Antisymmetric Molecular Dynamics
We have developed a new framework of Antisymmetrized Molecular Dynamics
(AMD), to adequately treat the I=0 \={K}N interaction, which is essential to
study kaonic nuclei. The improved points are 1) pK/n\={K} mixing and 2)
total spin and isospin projections. These improvements enable us to investigate
various kaonic nuclei (ppnK, pppK, pppnK, BeK and
BK) systematically. We have found that they are deeply bound and
extremely dense with a variety of shapes.Comment: 10 pages, 5 figure
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