27,376 research outputs found
Precision measurement with an optical Josephson junction
We study a new type of Josephson device, the so-called "optical Josephson
junction" as proposed in Phys. Rev. Lett. {\bf 95}, 170402 (2005). Two
condensates are optically coupled through a waveguide by a pair of Bragg beams.
This optical Josephson junction is analogous to the usual Josephson junction of
two condensates weakly coupled via tunneling. We discuss the use of this
optical Josephson junction, for making precision measurements.Comment: 6 pages, 1 figur
Precedence-type Test based on Progressively Censored Samples
In this paper, we introduce precedence-type tests for testing the hypothesis that two distribution functions are equal, which is an extension of the precedence life-test rst proposed by Nelson (1963), when the two samples are progressively Type-II censored. The null distributions of the test statistics are derived. Critical values for some combination of sample sizes and censoring schemes for the proposed tests are presented. Then, we present the exact power functions under the Lehmann alternative, and compare the exact power as well as simulated power (under location-shift) of the proposed precedence test based on nonparametric estimates of CDF with other precedence-type tests. We then examine the power properties of the proposed test procedures through Monte Carlo simulations. Two examples are presented to illustrate all the test procedures discussed here. Finally, we make some concluding remarks.Precedence test; Product-limit estimator; Type-II progressive censoring; Life-testing; level of significance; power; Lehmann alternative; Monte Carlo simulations
High-Energy emissions from the Pulsar/Be binary system PSR J2032+4127/MT91 213
PSR J2032+4127 is a radio-loud gamma-ray-emitting pulsar; it is orbiting
around a high-mass Be type star with a very long orbital period of 25-50years,
and is approaching periastron, which will occur in late 2017/early 2018. This
system comprises with a young pulsar and a Be type star, which is similar to
the so-called gamma-ray binary PSR~B1259-63/LS2883. It is expected therefore
that PSR J2032+4127 shows an enhancement of high-energy emission caused by the
interaction between the pulsar wind and Be wind/disk around periastron. Ho et
al. recently reported a rapid increase in the X-ray flux from this system. In
this paper, we also confirm a rapid increase in the X-ray flux along the orbit,
while the GeV flux shows no significant change. We discuss the high-energy
emissions from the shock caused by the pulsar wind and stellar wind interaction
and examine the properties of the pulsar wind in this binary system. We argue
that the rate of increase of the X-ray flux observed by Swift indicates (1) a
variation of the momentum ratio of the two-wind interaction region along the
orbit, or (2) an evolution of the magnetization parameter of the pulsar wind
with the radial distance from the pulsar. We also discuss the pulsar wind/Be
disk interaction at the periastron passage, and propose the possibility of
formation of an accretion disk around the pulsar. We model high-energy
emissions through the inverse-Compton scattering process of the
cold-relativistic pulsar wind off soft photons from the accretion disk.Comment: 18 pages, 23 figures, 1 Table, accepted for publication in Ap
The X-ray modulation of PSR J2032+4127/MT91 213 during the Periastron Passage in 2017
We present the Neil Gehrels Swift Observatory (Swift), Fermi Large Area
Telescope (Fermi-LAT), and Karl G. Jansky Very Large Array (VLA) observations
of the gamma-ray binary PSR J2032+4127/MT91 213, of which the periastron
passage has just occurred in November 2017. In the Swift X-ray light curve, the
flux was steadily increasing before mid-October 2017, however, a sharp X-ray
dip on a weekly time-scale is seen during the periastron passage, followed by a
post-periastron X-ray flare lasting for ~20 days. We suggest that the X-ray dip
is caused by (i) an increase of the magnetization parameter at the shock, and
(ii) the suppression due to the Doppler boosting effect. The 20-day
post-periastron flare could be a consequence of the Be stellar disk passage by
the pulsar. An orbital GeV modulation is also expected in our model, however,
no significant variability is seen in the Fermi-LAT light curve. We suspect
that the GeV emission resulted from the interaction between the binary's
members is hidden behind the bright magnetospheric emission of the pulsar.
Pulsar gating technique would be useful to remove the magnetospheric emission
and recover the predicted GeV modulation, if an accurate radio timing solution
over the periastron passage is provided in the future.Comment: 6 pages, including 2 figures. Accepted for publication in Ap
Entanglement between atomic condensates in an optical lattice: effects of interaction range
We study the area-dependent entropy and two-site entanglement for two state
Bose-Einstein condensates in a 2D optical lattice. We consider the case where
the array of two component condensates behave like an ensemble of spin-half
particles with the interaction to its nearest neighbors and next nearest
neighbors. We show how the Hamiltonian of their Bose-Einstein condensate
lattice with nearest-neighbor and next-nearest-neighbor interactions can be
mapped into a harmonic lattice. We use this to determine the entropy and
entanglement content of the lattice.Comment: 5 pages, 3 figures, title change
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