410 research outputs found
Universal quantum computation with the Orbital Angular Momentum of a single photon
We prove that a single photon with quantum data encoded in its orbital
angular momentum can be manipulated with simple optical elements to provide any
desired quantum computation. We will show how to build any quantum unitary
operator using beamsplitters, phase shifters, holograms and an extraction gate
based on quantum interrogation. The advantages and challenges of these approach
are then discussed, in particular the problem of the readout of the results.Comment: First version. Comments welcom
Current status of the Tiger Grouper (Mycteroperca tigris) fishery at Vieques Island, Puerto Rico
Distribution and abundance of Queen Conch, Strombus gigas, (Gastropoda: Strombidae) on the shallow waters of the Jaragua National Park, Dominican Republic
Regional initiative for the evaluation of Queen Conch (Strombus gigas) exploitation under an historical perspective
Spatial and seasonal variation in leaf temperature within the canopy of a tropical forest
Understanding leaf temperature (Tleaf) variation in the canopy of tropical forests is critical for accurately calculating net primary productivity because plant respiration and net photosynthesis are highly sensitive to temperature. The objectives of this study were to (1) quantify the spatiotemporal variation of Tleaf in a semi-deciduous tropical forest in Panama and (2) create a season-specific empirical model to predict Tleaf in the canopy. To achieve this, we used a 42 m tall construction crane for canopy access and monitored the microenvironment within the canopy of mature, 20-35 m tall trees of 5 tropical tree species during the wet and the dry season. Tleaf was correlated to photosynthetic photon flux density (PPFD) in the wet season but not in the dry season, possibly due to seasonal differences in wind speed, physiology, and canopy phenology. A structural equation model showed that Tleaf is best explained by air temperature (Tair) and PPFD in the wet season, whereas in the dry season, Tair alone predicted most of the variation in Tleaf. These results suggest the utility of an empirical approach to estimate Tleaf variability where simple meteoro logical data are available. This approach can be incorporated in future models of vegetation-atmosphere carbon and water exchange models of mature tropical forests with similar seasonality. © Inter-Research 2016
Delayed commutation in quantum computer networks
In the same way that classical computer networks connect and enhance the
capabilities of classical computers, quantum networks can combine the
advantages of quantum information and communications. We propose a
non-classical network element, a delayed commutation switch, that can solve the
problem of switching time in packet switching networks. With the help of some
local ancillary qubits and superdense codes we can route the information after
part of it has left the network node.Comment: 4 pages. 4 figures. Preliminar versio
Quantum Multiplexing with the Orbital Angular Momentum of light
The orbital angular momentum, OAM, of photons offers a suitable support to
carry the quantum data of multiple users. We present two novel optical setups
that send the information of n quantum communication parties through the same
free-space optical link. Those qubits can be sent simultaneously and share
path, wavelength and polarization without interference, increasing the
communication capacity of the system. The first solution, a qubit combiner,
merges n channels into the same link, which transmits n independent photons.
The second solution, the OAM multiplexer, uses CNOT gates to transfer the
information of n optical channels to a single photon. Additional applications
of the multiplexer circuits, such as quantum arithmetic, as well as connections
to OAM sorting are discussed
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