3,982 research outputs found
Measurement enhances long-distance Entanglement generation in spin chains with dissipative processes
In this paper, effects of the regular measurements on a noisy channel has
been investigated. The strategy introduced by A. Bayat, and Y. Omar [New J.
Phys. 17, 103041 (2015)] is followed to suppress dephasing and dissipation
effects in a noisy spin channel and generate long distance entanglement by
global measurement on the channel. A regular global measurements performed on
spin channel weakly coupled to the sender and receiver qubits via
interaction. This scheme is applied for the dephasing and dissipation in
non-zero temperature processes separately and the results show that amounts of
achieved entanglement enhanced rather than the no-measurement approach.Comment: 6 pages, 6 figures, Comments welcom
Integrable models of galactic discs with double nuclei
We introduce a new class of 2-D mass models, whose potentials are of
St\"ackel form in elliptic coordinates. Our model galaxies have two separate
strong cusps that form double nuclei. The potential and surface density
distributions are locally axisymmetric near the nuclei and become {\it highly}
non-axisymmetric outside the nucleus. The surface density diverges toward the
cuspy nuclei with the law . Our model is sustained by
four general types of regular orbits: {\it butterfly}, {\it nucleuphilic
banana}, {\it horseshoe} and {\it aligned loop} orbits. Horseshoes and
nucleuphilic bananas support the existence of cuspy regions. Butterflies and
aligned loops control the non-axisymmetric shape of outer regions. Without any
need for central black holes, our distributed mass models resemble the nuclei
of M31 and NGC4486B. It is also shown that the self-gravity of the stellar disc
can prevent the double nucleus to collapse.Comment: 8 pages, accepted for publication in MNRA
Universal feedback control of two-qubit entanglement
We consider two-qubit undergoing local dissipation and subject to local
driving. We then determine the optimal Markovian feedback action to preserve
initial entanglement as well as to create stationary entanglement with the help
of an XY interaction Hamiltonian. Such feedback actions are worked out in a way
not depending on the initial two-qubit state, whence called universal.Comment: 10 pages, 6 figure
Receptor-Mediated Endocytosis of a Cylindrical Nanoparticle in the Presence of Cytoskeleton Substrate
Internalization of particles by cells plays a crucial role for adsorbing
nutrients and fighting infection. Endocytosis is one of the most important
mechanisms of the particles uptake which encompass multiple pathways. Although
endocytosis is a complex mechanism involving biochemical signaling and active
force generation, the energetic cost associated to the large deformations of
the cell membrane wrapping around the foreign particle is an important factor
controlling this process, which can be studied using quantitative physical
models. Of particular interest is the competition between membrane -
cytoskeleton and membrane - target adhesion. Here, we explore the wrapping of a
lipid membrane around a long cylindrical object in the presence of a substrate
mimicking the cytoskeleton. Using discretization of the Helfrich elastic energy
that accounts for the membrane bending rigidity and surface tension, we obtain
a wrapping phase diagram as a function of the membrane-cytoskeleton and the
membrane-target adhesion energy that includes unwrapped, partially wrapped and
fully wrapped states. We provide an analytical expression for the boundary
between the different regimes. While the transition to partial wrapping is
independent of membrane tension, the transition to full wrapping is very much
influenced by membrane tension. We also show that target wrapping may proceed
in an asymmetric fashion in the full wrapping regime
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