5,661 research outputs found
Redistribution of particle and anti-particle entanglement in non-inertial frames
We analyse the entanglement tradeoff between particle and anti-particle modes
of a Dirac field from the perspective of inertial and uniformly accelerated
observers. Our results show that a redistribution of entanglement between
particle and anti-particle modes plays a key role in the survival of fermionic
field entanglement in the infinite acceleration limit.Comment: 10 pages, 5 figures, revtex4. Added journal referenc
Optimal conclusive teleportation of quantum states
Quantum teleportation of qudits is revisited. In particular, we analyze the
case where the quantum channel corresponds to a non-maximally entangled state
and show that the success of the protocol is directly related to the problem of
distinguishing non-orthogonal quantum states. The teleportation channel can be
seen as a coherent superposition of two channels, one of them being a maximally
entangled state thus, leading to perfect teleportation and the other,
corresponding to a non-maximally entangled state living in a subspace of the
d-dimensional Hilbert space. The second channel leads to a teleported state
with reduced fidelity. We calculate the average fidelity of the process and
show its optimality.Comment: 8 pages, revtex, no figure
Inelastic collisions in an exactly solvable two-mode Bose-Einstein Condensate
Inelastic collisions occur in Bose-Einstein condensates, in some cases,
producing particle loss in the system. Nevertheless, these processes have not
been studied in the case when particles do not escape the trap. We show that
such inelastic processes are relevant in quantum properties of the system such
as the evolution of the relative population, the self trapping effect and the
probability distribution of particles. Moreover, including inelastic terms in
the model of the two-mode condensate allows for an exact analytical solution.
Using this solution, we show that collisions favor the generation of
entanglement between the modes of the condensate as long as the collision rate
does not exceed the natural frequency of the system
Trans-Neptunian Objects with Hubble Space Telescope ACS/WFC
We introduce a novel search technique that can identify trans-neptunian
objects in three to five exposures of a pointing within a single Hubble Space
Telescope orbit. The process is fast enough to allow the discovery of
candidates soon after the data are available. This allows sufficient time to
schedule follow up observations with HST within a month. We report the
discovery of 14 slow-moving objects found within 5\circ of the ecliptic in
archival data taken with the Wide Field Channel of the Advanced Camera for
Surveys. The luminosity function of these objects is consistent with previous
ground-based and space-based results. We show evidence that the size
distribution of both high and low inclination populations is similar for
objects smaller than 100 km, as expected from collisional evolution models,
while their size distribution differ for brighter objects. We suggest the two
populations formed in different parts of the protoplanetary disk and after
being dynamically mixed have collisionally evolved together. Among the objects
discovered there is an equal mass binary with an angular separation ~ 0."53.Comment: 16 page, 10 figures, accepted by Ap
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