Universal decoherence induced by an environmental quantum phase transition

Decoherence induced by coupling a system with an environment may display universal features. Here we demostrate that when the coupling to the system drives a quantum phase transition in the environment, the temporal decay of quantum coherences in the system is Gaussian with a width independent of the system-environment coupling strength. The existence of this effect opens the way for a new type of quantum simulation algorithm, where a single qubit is used to detect a quantum phase transition. We discuss possible implementations of such algorithm and we relate our results to available data on universal decoherence in NMR echo experiments

Necessary symmetry conditions for the rotation of light

Two conditions on symmetries are identified as necessary for a linear scattering system to be able to rotate the linear polarisation of light: Lack of at least one mirror plane of symmetry and electromagnetic duality symmetry. Duality symmetry is equivalent to the conservation of the helicity of light in the same way that rotational symmetry is equivalent to the conservation of angular momentum. When the system is a solution of a single species of particles, the lack of at least one mirror plane of symmetry leads to the familiar requirement of chirality of the individual particle. With respect to helicity preservation, according to the analytical and numerical evidence presented in this paper, the solution preserves helicity if and only if the individual particle itself preserves helicity. However, only in the particular case of forward scattering the helicity preservation condition on the particle is relaxed: We show that the random orientation of the molecules endows the solution with an effective rotational symmetry; at its turn, this leads to helicity preservation in the forward scattering direction independently of any property of the particle. This is not the case for a general scattering direction. These results advance the current understanding of the phenomena of molecular optical activity and provide insight for the design of polarisation control devices at the nanoscale.Comment: 17 pages, 3 figure

One-Shot Drilling Analysis of Stack CFRP/UNS A92024 Bonding by Adhesive

The use of adhesive layers can improve the properties and reduce the defects produced in the interfaces. This provides adherence to the structure, adapting the joining surfaces and avoiding spaces between the layers. However, the presence of the adhesive can potentiate the defects caused during drilling. In turn, a loss of adhesive in the interface can occur during machining affecting the final structure. This work has followed a conventional OSD strategy in CFRP and UNS A92024 aluminium sheet stacking with adhesive. A series of dry drilling tests have been developed with different cutting conditions and new noncoated WC-Co helical cutting tools. Analysis of Variance (ANOVA) statistical analyses and surface response models have been applied to determine the mechanical behaviour in the holes. For this purpose, the dimensional deviation, surface quality, and adhesive loss in the interface in relation to the number of holes have been considered. A combination of cutting parameters that minimizes the evaluated defects has been found. Diametric deviations and surface qualities below 2% and 3.5 m have been measured in the materials that make up the stack with cutting speeds higher than 140 m/min and feed rates between 200 and 250 mm/min. However, the greatest adhesive losses occur at high cutting speeds

Far-field measurements of vortex beams interacting with nanoholes

We measure the far-field intensity of vortex beams going through nanoholes. The process is analyzed in terms of helicity and total angular momentum. It is seen that the total angular momentum is preserved in the process, and helicity is not. We compute the ratio between the two transmitted helicity components, $\gamma_{m,p}$. We observe that this ratio is highly dependent on the helicity ($p$) and the angular momentum ($m$) of the incident vortex beam in consideration. Due to the mirror symmetry of the nanoholes, we are able to relate the transmission properties of vortex beams with a certain helicity and angular momentum, with the ones with opposite helicity and angular momentum. Interestingly, vortex beams enhance the $\gamma_{m,p}$ ratio as compared to those obtained by Gaussian beams

Theory of extraordinary transmission of light through quasiperiodic arrays of subwavelength holes

By using a theoretical formalism able to work in both real and k-spaces, the physical origin of the phenomenon of extraordinary transmission of light through quasi-periodic arrays of holes is revealed. Long-range order present in a quasiperiodic array selects the wavevector(s) of the surface electromagnetic mode(s) that allows an efficient transmission of light through subwavelength holes.Comment: 4 pages, 4 figure

Magnetic-field control of near-field radiative heat transfer and the realization of highly tunable hyperbolic thermal emitters

We present a comprehensive theoretical study of the magnetic field dependence of the near-field radiative heat transfer (NFRHT) between two parallel plates. We show that when the plates are made of doped semiconductors, the near-field thermal radiation can be severely affected by the application of a static magnetic field. We find that irrespective of its direction, the presence of a magnetic field reduces the radiative heat conductance, and dramatic reductions up to 700% can be found with fields of about 6 T at room temperature. We show that this striking behavior is due to the fact that the magnetic field radically changes the nature of the NFRHT. The field not only affects the electromagnetic surface waves (both plasmons and phonon polaritons) that normally dominate the near-field radiation in doped semiconductors, but it also induces hyperbolic modes that progressively dominate the heat transfer as the field increases. In particular, we show that when the field is perpendicular to the plates, the semiconductors become ideal hyperbolic near-field emitters. More importantly, by changing the magnetic field, the system can be continuously tuned from a situation where the surface waves dominate the heat transfer to a situation where hyperbolic modes completely govern the near-field thermal radiation. We show that this high tunability can be achieved with accessible magnetic fields and very common materials like n-doped InSb or Si. Our study paves the way for an active control of NFRHT and it opens the possibility to study unique hyperbolic thermal emitters without the need to resort to complicated metamaterials.Comment: 21 pages, 10 figure

Comparison of micronuclei frequency in bone marrow cells of three rat lines

The aim of this paper is to compare the spontaneous and induced with cyclophosphamide micronucleus indexes in bone marrow cells of the Sprague Dawley, Lewis and Wistar rat lines. Five experimental groups were formed (10 animals of each sex and of each line, in every group). The first group was used as the negative control (intact animals), the second one was exposed to oral administration of drugs; other conditions were the same as for the other groups. The third group was treated with 2 % Tween 65 and the fourth group was treated with 0.9 % NaCl. Both substances were administered by oral way to 2 ml/kg during 14 days. The fifth group was treated intraperitoneally with strong mutagen cyclophosphamide in the dose of 50 mg/kg (10 ml/kg in solution), on 48th and 24th hours before euthanasia. The Sprague Dawley line (both sexes) was significantly different from the other lines. Rats of this line had lower index of spontaneous formation of micronuclei, higher index of cyclophosphamide­induced micronucle formation, percent of micronucleated erythrocytes in bone marrow and the index of cytotoxicity. The results obtained make it possible to identify the most appropriate line of rats as model animals for studies of genotoxicity. It will allow also to obtain more accurate estimates of genotoxicity of various substances.Сравнивали спонтанные и индуцированные циклофосфамидом микроядерные индексы в клетках костного мозга трех линий крыс – Sprague Dawley, Льюис и Вистар. Сформировали пять экспериментальных групп (по 10 животных каждого пола и линии в каждой группе). Первую группу использовали в качестве негативного контроля (интактные животные), вторая служила контролем влияния перорального приема препаратов. Все условия содержания были одинаковыми для всех групп животных. Крыс третьей группы обрабатывали 2 % Tween 65, а четвертой группы – 0,9 % NaCl. Оба вещества вводили перорально в дозе 2 мл/кг в течение 14 дней. Животных пятой группы обрабатывали внутрибрюшинно циклофосфамидом в дозе 50 мг/кг (10 мл/кг раствора), за 48 и 24 ч до эвтаназии. Линия Sprague Dawley (оба пола) существенно отличается от других. Крысы этой линии имели низкие показатели спонтанного образования микроядер и высокий индекс при индукции циклофосфамидом, а также процент эритроцитов с микроядрами в костном мозге и индекс цитотоксичности. Полученные результаты позволяют определить наиболее подходящие линии крыс в качестве модельных животных для изучения генотоксичности. Это также позволит получать более точные оценки генотоксичности различных веществ. Порівнювали спонтанні та індуковані циклофосфамідом мікроядерні індекси в клітинах кісткового мозку трьох ліній щурів – Sprague Dawley, Люіс і Вистар.Сформували п’ять експериментальних груп (по 10 тварин кожної статі і лінії в кожній групі). Першу групу використали як негативний контроль (інтактні тварини), друга слугувала контролем впливу перорального прийому препаратів. Всі умови утримання були однаковими для всіх груп тварин. Щурів третьої групи обробляли 2 % Тween 65, а четвертої групи – 0,9 % NaCl. Обидві речовини вводили перорально в дозі 2 мл/кг впродовж 14 днів. Тварин п’ятої групи обробляли внутрішньочеревно циклофосфамідом в дозі 50 мг/кг (10 мл/кг розчину), за 48 і 24 год до евтаназії. Лінія Sprague Dawley (обидві статі) істотно відрізнялась від інших. Щури цієї лінії мали низькі показники спонтанного утворення мікроядер і високий індекс при індукції циклофосфамідом, а також відсоток еритроцитів з мікроядрами в кістковому мозку та індекс цитотоксичності. Отримані результати дозволяють визначити найбільш відповідні лінії щурів як модельних тварин для вивчення генотоксичності. Це також дозволить отримувати точніші оцінки генотоксичності різних речовин

Los adhesivos empleados en el entelado de carteles modernos. Uso de la Espectrometría de Masas de Ionización/Desorción por Láser asistida por Matriz y analizador de Tiempo de Vuelo (MALDI-TOF-MS) para la identificación de éteres de celulosa

"XVIII Congreso Internacional de Conservación y Restauración de Bienes Culturales - 18th International Meeting on Heritage Conservation", Granada 9 al 11 novembre de 201