2,982 research outputs found
Magnetar Flare-Driven Bumpy Declining Light Curves in Hydrogen-poor Superluminous Supernovae
Recent observations indicate that hydrogen-poor superluminous supernovae
often display bumpy declining light curves. However, the cause of these
undulations remains unclear. In this paper, we have improved the magnetar
model, which includes flare activities. We present a systematic analysis of a
well-observed SLSNe-I sample with bumpy light curves in the late-phase. These
SLSNe-I were identified from multiple transient surveys, such as the
Pan-STARRS1 Medium Deep Survey (PS1 MDS) and the Zwicky Transient Facility
(ZTF). Our study provides a set of magnetar-powered model light curve fits for
five SLSNe-I, which accurately reproduce observed light curves using reasonable
physical parameters. By extracting essential characteristics of both explosions
and central engines, these fits provide valuable insights into investigating
their potential association with gamma ray burst engines. We found that the
SLSN flares tend to be the dim and long extension of the GRB flares in the peak
luminosity versus peak time plane. Conducting large-scale, high cadence surveys
in the near future could enhance our comprehension of both SLSN undulation
properties and their potential relationship with GRBs by modeling their light
curve characteristics.Comment: 10 pages, 5 figures. Accepted for publication in the Astrophysical
Journa
Generation of 3-Dimensional graph state with Josephson charge qubits
On the basis of generations of 1-dimensional and 2-dimensional graph states,
we generate a 3-dimensional N3-qubit graph state based on the Josephson charge
qubits. Since any two charge qubits can be selectively and effectively coupled
by a common inductance, the controlled phase transform between any two-qubit
can be performed. Accordingly, we can generate arbitrary multi-qubit graph
states corresponding to arbitrary shape graph, which meet the expectations of
various quantum information processing schemes. All the devices in the scheme
are well within the current technology. It is a simple, scalable and feasible
scheme for the generation of various graph states based on the Josephson charge
qubits.Comment: 4 pages, 4 figure
2-(2-Methyl-5-nitro-1H-imidazol-1-yl)ethyl N-methylÂcarbamate
In the title compound, C8H12N4O4, the essentially planar methylÂcarbamoyloxymethyl group [maximum deviation 0.038 (3) Å] and the imidazole ring make a dihedral angle of 48.47 (3)°. The crystal packing is stabilized by interÂmolecular N—H⋯N and C—H⋯O hydrogen bonds, which link the molÂecules into infinite ribbons running along the a axis, and by weak π–π stacking interÂactions [centroid–centroid distance = 3.894 (2) Å]
Generating Giant and Tunable Nonlinearity in a Macroscopic Mechanical Resonator from Chemical Bonding Force
Nonlinearity in macroscopic mechanical system plays a crucial role in a wide
variety of applications, including signal transduction and processing,
synchronization, and building logical devices. However, it is difficult to
generate nonlinearity due to the fact that macroscopic mechanical systems
follow the Hooke's law and response linearly to external force, unless strong
drive is used. Here we propose and experimentally realize a record-high
nonlinear response in macroscopic mechanical system by exploring the
anharmonicity in deforming a single chemical bond. We then demonstrate the
tunability of nonlinear response by precisely controlling the chemical bonding
interaction, and realize a cubic elastic constant of \mathversion{bold}, many orders of magnitude larger in strength
than reported previously. This enables us to observe vibrational bistate
transitions of the resonator driven by the weak Brownian thermal noise at 6~K.
This method can be flexibly applied to a variety of mechanical systems to
improve nonlinear responses, and can be used, with further improvements, to
explore macroscopic quantum mechanics
The Origin of the Prompt Emission for Short GRB 170817A: Photosphere Emission or Synchrotron Emission?
The first gravitational-wave event from the merger of a binary neutron star system (GW170817) was detected recently. The associated short gamma-ray burst (GRB 170817A) has a low isotropic luminosity (~1047 erg s−1) and a peak energy E p ~ 145 keV during the initial main emission between −0.3 and 0.4 s. The origin of this short GRB is still under debate, but a plausible interpretation is that it is due to the off-axis emission from a structured jet. We consider two possibilities. First, since the best-fit spectral model for the main pulse of GRB 170817A is a cutoff power law with a hard low-energy photon index (), we consider an off-axis photosphere model. We develop a theory of photosphere emission in a structured jet and find that such a model can reproduce a low-energy photon index that is softer than a blackbody through enhancing high-latitude emission. The model can naturally account for the observed spectrum. The best-fit Lorentz factor along the line of sight is ~20, which demands that there is a significant delay between the merger and jet launching. Alternatively, we consider that the emission is produced via synchrotron radiation in an optically thin region in an expanding jet with decreasing magnetic fields. This model does not require a delay of jet launching but demands a larger bulk Lorentz factor along the line of sight. We perform Markov Chain Monte Carlo fitting to the data within the framework of both models and obtain good fitting results in both cases
Bounds for entanglement of formation of two mode squeezed thermal states
The upper and lower bounds of entanglement of formation are given for two
mode squeezed thermal state. The bounds are compared with other entanglement
measure or bounds. The entanglement distillation and the relative entropy of
entanglement of infinitive squeezed state are obtained at the postulation of
hashing inequality.Comment: 3 figure
The separability of tripartite Gaussian state with amplification and amplitude damping
Tripartite three mode Gaussian state undergoes parametric amplification and
amplitude damping as well as thermal noise is studied. In the case of a state
totally symmetrically interacting with the environment, the time dependent
correlation matrix of the state in evolution is given. The conditions for fully
separability and fully entanglement of the final tripartite three mode Gaussian
state are worked out.Comment: 9 pages, 3 figure
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