Entanglement enhancement and postselection for two atoms interacting with thermal light

The evolution of entanglement for two identical two-level atoms coupled to a resonant thermal field is studied for two different families of input states. Entanglement enhancement is predicted for a well defined region of the parameter space of one of these families. The most intriguing result is the possibility of probabilistic production of maximally entangled atomic states even if the input atomic state is factorized and the corresponding output state is separable.Comment: accepted for publication in J. Phys.

A single structured light beam as an atomic cloud splitter

We propose a scheme to split a cloud of cold non-interacting neutral atoms based on their dipole interaction with a single structured light beam which exhibits parabolic cylindrical symmetry. Using semiclassical numerical simulations, we establish a direct relationship between the general properties of the light beam and the relevant geometric and kinematic properties acquired by the atomic cloud as its passes through the beam.Comment: 10 pages, 5 figure

Comment on "Fermionic entanglement ambiguity in noninertial frames"

In this comment we show that the ambiguity of entropic quantities calculated in Physical Review A 83, 062323 (2011) for fermionic fields in the context of Unruh effect is not related to the properties of anticommuting fields, as claimed in Physical Review A 83, 062323 (2011), but rather to wrong mathematical manipulations with them and not taking into account a fundamental superselection rule of quantum field theory.Comment: To appear in Physical Review A. Some of the problems discussed in this comment can also be found in other previously published papers studying the Unruh effect for fermions (in the context of quantum information theory). An extended version of the comment can be found here http://arxiv.org/abs/1108.555

Alternativas tecnológicas para el desarrollo sostenible de la producción láctea en áreas con distintos grados de restricciones edafoclimáticas del NE de la Provincia de Santa Fe.

El objetivo del trabajo, es disponer de información local respecto a las características de los sistemas lecheros y la calidad de la leche que se obtiene en el NE de la Provincia de Santa Fe, y desarrollar nuevas alternativas tecnológicas para mejorar la productividad e incrementar el valor agregado de los productos lácteos. Se relevó información (2013- 2015), sobre la dieta ofrecida al rodeo lechero, y se analizó la leche cruda para determinar el perfil de los ácidos grasos, en establecimientos de producción lechera ubicados: Norte del departamento San Justo, Sur del departamento Vera, departamento General Obligado, y Norte del departamento San Javier. Se seleccionaron cultivares de alfalfa con adaptación sitio específica, con ensayos en las localidades de Calchaquí y Vera y Pintado (departamentos Vera y San Justo). Se utilizó un diseño experimental de bloques completos aleatorizados con 4 repeticiones. Se implantaron 40 cultivares de alfalfa, pertenecientes a los grados de reposo invernal 6, 7, 8, 9 y 10. La variedad con mayor producción en Calchaquí (1° corte) fue Sirosal (4.135 kg MS/ha.) y en Vera y Pintado, variedad Brava GS (2.093 kg MS/ha.). En el 2do corte, la variedad de mayor producción en ambos sitios fue Brava GS, con 3.435 kg MS/ha. Calchaquí y 3.585 kg MS/ha. en Vera y Pintado. Los cultivares WL 1058, Trinidad 87, CW 194 Premium, ProINTA Monarca y WL 818 manifestaron una producción semejante en ambos ambientes, mientras que los cultivares Sirosal, WL 919, Aurora, Sardi, Pampa Flor, CW 809, P 30 y Verdor muestran elevada interacción genotipo x ambiente. Se observó que los productores adoptan las mismas pasturas y cultivos que la región pampeana, con menor productividad. Con producciones < 500 lts/día en promedio, 80% de los productores utilizan alfalfa y predomina el cultivo de sorgo tanto forrajero como granífero. Entre 1000 a 2000 lts/día, y >2000 lts/día, el 100% siembra alfalfa, y verdeos de maíz, sorgo forrajero y granífero, y moha. Con mayores escalas de producción (>1000 lts/día), aumenta el uso de silaje y de concentrados. Es bajo el porcentaje de utilización de semillas de algodón. El valor máximo obtenido de CLA en leche cruda de la zona de la cuenca pampeana corresponde a un valor de 1.41 mg/100g, mientras que en dicha zona se observa valor máximode CLA de 2.24 mg/100g.publishedVersio

Relativistically covariant state-dependent cloning of photons

The influence of the relativistic covariance requirement on the optimality of the symmetric state-dependent 1 -> 2 cloning machine is studied. Namely, given a photonic qubit whose basis is formed from the momentum-helicity eigenstates, the change to the optimal cloning fidelity is calculated taking into account the Lorentz covariance unitarily represented by Wigner's little group. To pinpoint some of the interesting results, we found states for which the optimal fidelity of the cloning process drops to 2/3 which corresponds to the fidelity of the optimal classical cloner. Also, an implication for the security of the BB84 protocol is analyzed.Comment: corrected, rewritten and accepted in PR

Capacities of Grassmann channels

A new class of quantum channels called Grassmann channels is introduced and their classical and quantum capacity is calculated. The channel class appears in a study of the two-mode squeezing operator constructed from operators satisfying the fermionic algebra. We compare Grassmann channels with the channels induced by the bosonic two-mode squeezing operator. Among other results, we challenge the relevance of calculating entanglement measures to assess or compare the ability of bosonic and fermionic states to send quantum information to uniformly accelerated frames.Comment: 33 pages, Accepted in Journal of Mathematical Physics; The role of the (fermionic) braided tensor product for quantum Shannon theory, namely capacity formulas, elucidated; The conclusion on the equivalence of Unruh effect for bosons and fermions for quantum communication purposes made clear and even more precis

Quantum Mechanical Properties of Bessel Beams

Bessel beams are studied within the general framework of quantum optics. The two modes of the electromagnetic field are quantized and the basic dynamical operators are identified. The algebra of these operators is analyzed in detail; it is shown that the operators that are usually associated to linear momentum, orbital angular momentum and spin do not satisfy the algebra of the translation and rotation group. In particular, what seems to be the spin is more similar to the helicity. Some physical consequences of these results are examined.Comment: 17 pages, no figures. New versio