Bilinear and quadratic Hamiltonians in two-mode cavity quantum electrodynamics

In this work we show how to engineer bilinear and quadratic Hamiltonians in cavity quantum electrodynamics (QED) through the interaction of a single driven two-level atom with cavity modes. The validity of the engineered Hamiltonians is numerically analyzed even considering the effects of both dissipative mechanisms, the cavity field and the atom. The present scheme can be used, in both optical and microwave regimes, for quantum state preparation, the implementation of quantum logical operations, and fundamental tests of quantum theory.Comment: 11 pages, 3 figure

Nonadiabatic coherent evolution of two-level systems under spontaneous decay

In this paper we extend current perspectives in engineering reservoirs by producing a time-dependent master equation leading to a nonstationary superposition equilibrium state that can be nonadiabatically controlled by the system-reservoir parameters. Working with an ion trapped inside a nonindeal cavity we first engineer effective Hamiltonians that couple the electronic states of the ion with the cavity mode. Subsequently, two classes of decoherence-free evolution of the superposition of the ground and decaying excited levels are achieved: those with time-dependent azimuthal or polar angle. As an application, we generalise the purpose of an earlier study [Phys. Rev. Lett. 96, 150403 (2006)], showing how to observe the geometric phases acquired by the protected nonstationary states even under a nonadiabatic evolution.Comment: 5 pages, no figure

Jean-Baptiste Debret

FINEPUFRJFUJBIBEPFAPERJME

O Brasil e o colonialismo europeu

FINEPUFRJFUJBIBEPFAPERJME

A Study of Single- and Double-Averaged Second-Order Models to Evaluate Third-Body Perturbation Considering Elliptic Orbits for the Perturbing Body

The equations for the variations of the Keplerian elements of the orbit of a spacecraft perturbed by a third body are developed using a single average over the motion of the spacecraft, considering an elliptic orbit for the disturbing body. A comparison is made between this approach and the more used double averaged technique, as well as with the full elliptic restricted three-body problem. the disturbing function is expanded in Legendre polynomials up to the second order in both cases. the equations of motion are obtained from the planetary equations, and several numerical simulations are made to show the evolution of the orbit of the spacecraft. Some characteristics known from the circular perturbing body are studied: circular, elliptic equatorial, and frozen orbits. Different initial eccentricities for the perturbed body are considered, since the effect of this variable is one of the goals of the present study. the results show the impact of this parameter as well as the differences between both models compared to the full elliptic restricted three-body problem. Regions below, near, and above the critical angle of the third-body perturbation are considered, as well as different altitudes for the orbit of the spacecraft.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Inst Nacl Pesquisas Espaciais, BR-12227010 Sao Jose Dos Campos, SP, BrazilUniversidade Federal de São Paulo UNIFESP, BR-12231280 Sao Jose Dos Campos, SP, BrazilUniversidade Federal de São Paulo UNIFESP, BR-12231280 Sao Jose Dos Campos, SP, BrazilCNPq: 150195/2012-5CNPq: 304700/2009-6FAPESP: 2011/09310-7FAPESP: 2011/08171-3Web of Scienc

Using low Lift-to-Drag spacecraft to perform upper atmospheric Aero-Gravity Assisted Maneuvers

The Gravity Assisted Maneuver has been applied in lots of space missions, to change the spacecraft heliocentric velocity vector and the geometry of the orbit, after the close approach to a celestial body, saving propellant consumption. It is possible to take advantage of additional forces to improve the maneuver, like the forces generated by the spacecraft-atmosphere interaction and/or propulsion systems; reducing the time of flight and the need for multiple passages around secondary bodies. However, these applications require improvements in critical subsystems, which are necessary to accomplish the mission. In this paper, a few combinations of the Gravity-Assist were classified, including maneuvers with thrust and aerodynamic forces; presenting the advantages and limitations of these variations. There are analyzed the effects of implementing low Lift-to-Drag ratios at high altitudes for Aero-gravity Assist maneuvers, with and without propulsion. The maneuvers were simulated for Venus and Mars, due to their relevance in interplanetary missions, the interest in exploration, and the knowledge about their atmospheres. The Aero-gravity Assist maneuver with low Lift-to-Drag ratios at high altitudes shows an increase of more than 10{\deg} in the turn angle for Venus and 2.5{\deg} for Mars. The maneuvers increase the energy gains by more than 15% when compared to the Gravity-Assist. From the Technology Readiness Levels, it was observed that the current level of development of the space technology makes feasible the application of Aero-gravity Assisted Maneuvers at high altitudes in short term

Superscars in the LiNC=LiCN isomerization reaction

We demonstrate the existence of superscarring in the LiNC=LiCN isomerization reaction described by a realistic potential interaction in the range of readily attainable experimental energies. This phenomenon arises as the effect of two periodic orbits appearing "out of the blue"in a saddle--node bifurcation taking place in the dynamics of the system. Potential practical consequences of this superlocalization in the corresponding wave functions are also considered.Comment: 6 pages, 5 figures. to appear in EP

Applying the perturbative integral in aeromaneuvers around Mars to calculate the cost

The perturbative integral method was applied to quantify the contribution of external forces during a specific interval of time in trajectories of spacecraft around asteroids and under the Luni-solar influence. However, this method has not been used to quantify the contributions of drag in aerocapture and aerobraking. For this reason, the planet Mars is selected to apply this method during an aerogravity-assisted maneuver. Several trajectories are analyzed, making use of a drag device with area to mass ratios varying from 0.0 to 20.0 m2/kg, simulating solar sails or de-orbit devices. The mathematical model is based in the restricted three-body problem. The use of this maneuver makes it possible to obtain the variations of energy in the trajectory, replacing expensive maneuvers based on fuel consumption. To observe the effects of the maneuvers, different values of pericenter velocity and altitude were selected for prograde and retrograde orbits. The innovation of this research is the application of an integral method to quantify the delta-V of the aero gravity maneuver, comparing the cost of the maneuver with the traditional methods of space propulsion. The results allow the identification of orbits with conditions to capture, and the perturbative maps show the velocity variations

Protein extract and activity antioxidant of corn (Zea mays) and sorghum (Sorghum bicolor L. Moench) grains

Brazil is a major producer of grains, such as sorgh um and corn, which are used for export. Sorghum and corn grains have in its composition 9.5% and 9. 8 protein, respectively. Proteins are the most abundant and most diverse functions in living syste ms molecules. Currently, food proteins are increasingly recognized as a source of beneficial b ioactive peptides, and they are physiologically released during digestion. The aim of the work was to evaluate the protein extraction (four methods) and antioxidant activity of sorghum and corn grains . The proximal composition of grains was evaluated in relation to moisture, protein, lipids and ash contents, furthermore were quantified proteins concentration and antioxidant activity by FRAP method in the four extracts. The corn and sorghum grains were ground, homogenized (60 mesh) a nd stored at 5°C until analysis. The protein extraction utilized were: 1) dichloromethane/methan ol; 2) NH 4 HCO 3 (5mM, pH 8.0)/heat treatment; 3) water/ethanol/heat treatment; and 4) alkaline ex traction and precipitation. The corn and sorghum presented, protein 6.62% and 9.87%, lipids 4.45% an d 4.32%, moisture 8.87% and 8.23%, ash 0.96% and 1.15%, carbohydrates 79.01% and 76.41%, t otalizing a caloric value of 382.9 and 384.1 Kcal g -1 , respectively. The 2 and 3 methods in corn grain p resented highest protein content 133.16 and 142.24 μ g g -1 , respectively. In sorghum grain, methods 1, 2 and 3 presented protein content between 173.59 – 223.63 μg g -1 . The antioxidant activity of protein extracts was between 0.90 – 9.73μM of ferrous sulphate for corn and between 4.4 1 – 15.04μ M of ferrous sulphate for sorghum. The best results in the extraction using the method 3 for both grains could be due to the structure of proteins (zein and kafirins) which are soluble in a lcoholic solutions and insoluble in water. In conclusion, method 3 - water/ethanol/heat treatment (corn: 142.24 μg g -1 and sorghum: 223.63 μg g - 1 ) and method 3 (corn: 9.73 μM and sorghum: 15.04 μ M ) showed the best results for extracting protein and antioxidant activity, respectively. The protein extracts obtainedhave great potential as natural antioxidant

Protein extraction of the sunflower grains and bran

[Excerpt] Sunflower grains have a high protein content (24%) with high quality amino acid profile and are used to extraction of vegetable oil. The sunflower brain is produced during the processing of vegetal oil. The sunflower grains and by-product (bran) can be used with raw materials for obtaining peptides with bioactivity for protein hydrolysis after extraction, since they have great amount of essential amino acids, typically nonpolar, soluble and insoluble alcoholic solutions in water. The aim of this work was to evaluate protein extraction (three methods) of sunflower grains and bran. (...