Month: August 2019

Shrinking device makes objects appear smaller than they are

first_img Copyright 2011 All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of (a) A real spoon in the real space enclosed by the shrinking device. (b) The illusion object (a smaller spoon) in the virtual space. (c) A photograph of the shrinking device. A unit cell is shown in the inset. Image credit: Jiang, et al. ©2011 American Institute of Physics The team of engineers, led by Wei Xiang Jiang and Tie Jun Cui from Southeast University in Nanjing, China, has published their study on their shrinking device in a recent issue of Applied Physics Letters.“The shrinking device can shrink the size of an object virtually, so we named it a ‘shrinking device,’” Cui told “Such a device works at microwave frequencies and will confuse the radar or other electromagnetic detection equipment to make wrong decisions. Hence it may have potential applications in the military.”The researchers built the shrinking device out of metamaterials, which are best known for their role in invisibility cloaks. When used in the field of transformation optics, metamaterials can bend light and control its path in desired ways.Here, the researchers used metamaterials to build eight concentric rings that are each 12 mm high. They then placed an arbitrary object, such as a spoon, in the center of the rings. When light waves propagate through the shrinking device, the wave fronts begin to bend and their wavelengths get compressed. When the light reaches the inner circular region, the wavelengths become decompressed. To an observer on the outside of the shrinking device, the manipulated light creates the illusion of a smaller object with the same shape as the real object.“The device is designed by using transformation optics, which make the objects in the real space and virtual space look like the same,” said Cui. “In our design, the real object is a large one and the virtual object is a small one. With the help of shrinking device, the scattering field of the large object becomes the same as that of the small one.”As the researchers explained, the shrinking device works somewhat like the beginnings of an invisible cloak since both devices involve shrinking the radius of the inner circular region. For the shrinking device, the radius of this space is always positive. But as the radius approaches zero, the shrinking device becomes a perfect invisibility cloak.“An object can be made to appear arbitrarily small as desired,” said Cui.The researchers demonstrated the shrinking performance both numerically and experimentally, and found that the experimental results agreed very well with the simulations. The results showed that the device had an overall “good shrinking performance,” with the illusion looking like an exact smaller version of the original object.As the researchers noted, because some objects’ proportions depend on their sizes, the shrinking device could even generate virtual objects of small sizes that do not exist in nature.In addition, the methods used here to design the shrinking device could be extended to design and realize other illusion devices, such as devices that can change some of the other parameters of an object. ( — By controlling how light bends around an object, researchers have built a shrinking device that makes objects appear smaller than they actually are. Although the original object does not actually shrink, the illusion of the smaller object is convincing enough to confuse viewers since the real size of the object cannot be perceived. Invisibility cloak that generates virtual images gets closer to realization More information: Wei Xiang Jiang, et al. “Shrinking an arbitrary object as one desires using metamaterials.” Applied Physics Letters 98, 204101 (2011). DOI:10.1063/1.3590203 Explore further Citation: Shrinking device makes objects appear smaller than they are (2011, May 31) retrieved 18 August 2019 from This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

Diamond coupled to carbon nanotube could be used for quantum information processing

first_img Tiny diamonds could enable huge advances in nanotechnology © 2016 The researchers, Peng-Bo Li et al., have published a paper on the new hybrid quantum device in a recent issue of Physical Review Letters.Diamonds and carbon nanotubes, which are both carbon allotropes, each have their own unique properties that make building such a device possible. Diamond contains defects called nitrogen-vacancy centers that emit highly coherent bright red light. The defects’ optical properties can be well-controlled so that they occupy one of two distinct states, which enables the defects to act as qubits. Carbon nanotubes, for their part, are well-known for their highly advantageous mechanical and electrical properties. Both diamonds and carbon nanotubes have been widely studied as separate entities, but rarely together as an integrated device. Recently, related research has shown that the nitrogen-vacancy centers in diamond can be coupled to a mechanical resonator, such as a vibrating cantilever, so that the magnetic (spin) properties of the diamond are coupled to the mechanical motion of the resonator. However, the coupling strength in these devices has always been relatively weak. The new work expands upon this idea by coupling a nitrogen-vacancy center in diamond to a carbon nanotube, which can be made to resonate by sending a 60-µA electric current through it. The researchers explain that the coupling between the nanotube and diamond defect occurs for the same reason that an electric current creates a nearby magnetic field, but on the quantum scale.”This device corresponds to a quantum version of Oersted’s classical experiment: a current-carrying wire creates a magnetic field around it, which will produce a force acting on a magnetic needle,” Li, a physicist at RIKEN in Saitama, Japan, and Xi-an Jiaotong University in China, told to the exceptional properties of the two carbon allotropes, the resulting hybrid device exhibits a magnetic coupling strength that is three orders of magnitude stronger than previous related devices. The interaction between the two components can also be tuned by controlling the electric current through the nanotube.The researchers’ proposal also shows that the quantum states of the nitrogen-vacancy center and the nanotube can be transferred to one another when they are coupled, as well as to a distant diamond’s nitrogen-vacancy center that is coupled to the same vibration mode of the nanotube. In the future, the nitrogen-vacancy centers could be used as qubits, and the ability to quickly and efficiently control these qubits’ states could form the basis of quantum information processing systems, and also be used as nanoscale sensors.”This device could be used to mechanically address quantum logic gates based on electric spins and could serve as novel nanoscale sensors for detecting tiny pressure, temperature, electric, and magnetic-field changes in the physical and life sciences,” Li said.The researchers also found that this device behaves very similarly to cavity quantum electrodynamics (QED) devices, so that further improvements might be made by applying the wealth of knowledge on cavity QED to the new devices. Citation: Diamond coupled to carbon nanotube could be used for quantum information processing (2016, July 11) retrieved 18 August 2019 from (—By carefully placing a tiny piece of diamond within a few nanometers of a carbon nanotube, and then sending an electric current through the nanotube, researchers have designed a device that could one day form the building blocks of quantum information processing systems. In their recent study, they have shown that the electrified nanotube’s mechanical vibrations couple to the magnetic (or spin) properties of defects in the diamond. This coupling allows for the quantum states of the nanotube and diamond to be transferred to each other as well as to a second diamond positioned several micrometers away. More information: Peng-Bo Li et al. “Hybrid Quantum Device with Nitrogen-Vacancy Centers in Diamond Coupled to Carbon Nanotubes.” Physical Review Letters. DOI: 10.1103/PhysRevLett.117.015502center_img Two proposed set-ups for an experiment in which the nitrogen-vacancy (NV) center in a diamond nanocrystal is coupled to a nanotube with an electric current flowing through it: (a) the nanotube is suspended above the diamond, and (b) the diamond is above the nanotube. Credit: Li et al. ©2016 American Physical Society Explore further Journal information: Physical Review Letters This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

Calculations show close Ia supernova should be neutrino detectable offering possibility of

first_img More information: 1. Warren P. Wright et al. Neutrinos from type Ia supernovae: The gravitationally confined detonation scenario, Physical Review D (2017). DOI: 10.1103/PhysRevD.95.043006 , Arxiv: their use as cosmological distance indicators and their importance in the chemical evolution of Galaxies, the unequivocal identification of the progenitor systems and explosion mechanism of normal Type Ia supernova (SN Ia) remains elusive. The leading hypothesis is that such a supernova is a thermonuclear explosion of a carbon-oxygen white dwarf but the exact explosion mechanism is still a matter of debate. Observation of a Galactic SN Ia would be of immense value in answering the many open questions related to these events. One potentially useful source of information about the explosion mechanism and progenitor is the neutrino signal. In this paper we compute the expected neutrino signal from a Gravitationally Confined Detonation (GCD) explosion scenario for a SN~Ia and show how the flux at Earth contains features in time and energy unique to this scenario. We then calculate the expected event rates in the Super-K, Hyper-K, JUNO, DUNE, and IceCube detectors and find both Hyper-K and IceCube would see a few events for a GCD supernova at 1 kpc or closer, while Super-K, JUNO, and DUNE would see a events if the supernova were closer than ∼0.3 kpc. The distance and detector criteria needed to resolve the time and spectral features arising from the explosion mechanism, neutrino production, and neutrino oscillation processes are also discussed. The neutrino signal from the GCD is then compared with the signal from a Deflagration-to-Detonation Transition (DDT) explosion model computed previously. We find the overall event rate is the most discriminating feature between the two scenarios followed by the event rate time structure. Using the event rate in the Hyper-K detector alone, the DDT can be distinguished from the GCD at 2σ if the distance to the supernova is less than 2.3kpc for a normal mass ordering and 3.6kpc for an inverted ordering. 2. Warren P. Wright et al. Neutrinos from type Ia supernovae: The deflagration-to-detonation transition scenario, Physical Review D (2016). DOI: 10.1103/PhysRevD.94.025026 , Arxiv: has long been recognized that the neutrinos detected from the next core-collapse supernova in the Galaxy have the potential to reveal important information about the dynamics of the explosion and the nucleosynthesis conditions as well as allowing us to probe the properties of the neutrino itself. The neutrinos emitted from thermonuclear – type Ia – supernovae also possess the same potential, although these supernovae are dimmer neutrino sources. For the first time, we calculate the time, energy, line of sight, and neutrino-flavor-dependent features of the neutrino signal expected from a three-dimensional delayed-detonation explosion simulation, where a deflagration-to-detonation transition triggers the complete disruption of a near-Chandrasekhar mass carbon-oxygen white dwarf. We also calculate the neutrino flavor evolution along eight lines of sight through the simulation as a function of time and energy using an exact three-flavor transformation code. We identify a characteristic spectral peak at ∼10 MeV as a signature of electron captures on copper. This peak is a potentially distinguishing feature of explosion models since it reflects the nucleosynthesis conditions early in the explosion. We simulate the event rates in the Super-K, Hyper-K, JUNO, and DUNE neutrino detectors with the SNOwGLoBES event rate calculation software and also compute the IceCube signal. Hyper-K will be able to detect neutrinos from our model out to a distance of ∼10 kpc. At 1 kpc, JUNO, Super-K, and DUNE would register a few events while IceCube and Hyper-K would register several tens of events. (—A team of researchers at North Carolina State University has found that current and future neutrino detectors placed around the world should be capable of detecting neutrinos emitted from a relatively close supernova. They also suggest that measuring such neutrinos would allow them to explain what goes on inside of a star during such an explosion—if the measurements match one of two models that the team has built to describe the inner workings of a supernova. Supernovae have been classified into different types depending on what causes them to occur—one type, called a la supernova, occurs when a white dwarf pulls in enough material from a companion, eventually triggering carbon fusion, which leads to a massive explosion. Researchers here on Earth can see evidence of a supernova by the light that is emitted. But astrophysicists would really like to know more about the companion and the actual process that occurs inside the white dwarf leading up to the explosion—and they believe that might be possible by studying the neutrinos that are emitted. In this new effort, a team led by Warren Wright calculated that neutrinos from a relatively nearby supernova should be detectable by current sensors already installed and working around the planet and by those that are in the works. Wright also headed two teams that have each written a paper describing one of two types of models that the team has built to describe the process that occurs in the white dwarf leading up to the explosion—both teams have published their work in the journal Physical Review Letters.The first model is called the deflagration-to-detonation transition; the second, the gravitationally confined detonation. Both are based on theory regarding interactions inside of the star and differ mostly in how spherically symmetric they are. The two types would also emit different kinds and amounts of neutrinos, which is why the team is hoping that the detectors capable of measuring them will begin to do so. That would allow the teams to compare their models against real measurable data, and in so doing, perhaps finally offer some real evidence of what occurs when stars explode. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. , Physical Review D Explore further New study suggests long ago brightest star explosion was rapid type Ia supernovacenter_img Density contour plots including deflagration (white) and detonation (green) surfaces. Credit: arXiv:1609.07403 [astro-ph.HE] , arXiv Citation: Calculations show close Ia supernova should be neutrino detectable offering possibility of identifying explosion type (2017, March 3) retrieved 18 August 2019 from Journal information: Physical Review Letters © 2017 Phys.orglast_img read more

New study uncovers insights about the nature of the ultravioletbright star Barnard

first_img Citation: New study uncovers insights about the nature of the ultraviolet-bright star Barnard 29 (2019, March 11) retrieved 18 August 2019 from GHRS spectrum of Barnard 29. Credit: Dixon et al., 2019. Analyzing data from spectroscopic instruments, astronomers have reported fundamental properties of Barnard 29, an ultraviolet-bright star in globular cluster Messier 13. Results of the analysis, presented in a paper published March 1 on, provide important insights into the nature of this star. More information: William V. Dixon et al. Observations of the Ultraviolet-Bright Star Barnard 29 in the Globular Cluster M13 (NGC 6205). arXiv:1903.00350 [astro-ph.SR]. © 2019 Science X Network Barnard 29 has intrigued astronomers for over a century. It was described in the earliest studies as the most striking example of a star shining with a much bluer light than the great majority of the cluster’s other stars. According to more recent observations, Barnard 29 is classified as an ultraviolet-bright, post-asymptotic giant branch (AGB) star.Although Barnard 29 has been a subject of numerous observations, still many questions about its evolution and chemical composition remain unanswered. So a team of astronomers led by William V. Dixon of Space Telescope Science Institute in Baltimore, Maryland, has combed through the available data from the Hubble Space Telescope’s FUSE, COS and GHRS spectroscopic instruments and from the HIRES echelle spectrograph on the Keck I telescope in Hawaii. Analysis of this dataset allowed the researchers to determine chemical abundances for more than dozen elements in this star.”The availability of high-resolution, high signal-to-noise FUV and optical spectra allow us to confirm the star’s iron abundance and determine the abundances of many additional species,” the astronomers wrote in the paper.The research revealed that Barnard 29 has chemical composition typical for first-generation stars in Messier 13. The object was found to be richer in oxygen and poorer in aluminum than second-generation stars in this cluster.However, the star exhibits an underabundance of carbon and an overabundance of nitrogen, which indicates that it experienced a non-convective mixing on the red-giant branch (RGB) and did not undergo third dredge-up. Moreover, chemical abundances of Barnard 29 appear to have changed little since it left the RGB.”The abundance pattern seen in Barnard 29—C depletion and N enhancement relative to the average value for first-generation stars on the RGB—suggests that the star experienced the full impact of deep mixing,” the paper reads.Furthermore, the researchers found that Barnard 29 has an effective temperature of approximately 21,400 K and a mass of about 0.5 solar masses. They also found that iron abundance of this star is -6.05, consistent with the mean value for Messier 13.According to the paper, results of the study suggest that Barnard 29 evolved from a zero-age horizontal-branch (ZAHB) star with a mass of around 0.5-0.55 solar masses, near the boundary between the extreme and blue horizontal branches.”In light of stellar-evolution models, it seems likely that Barnard 29 is a post-HB star evolving from a ZAHB star with MZAHB between 0.50 and 0.55 M, a range spanning the EHB/BHB boundary. A post-HB star would have fully ascended the RGB, consistent with our suggestion that Barnard 29 experienced the full effects of non-convective mixing on the RGB,” the scientists explained. Explore further Astronomers reveal insights into the nature of a distant ultraviolet-bright star This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

Aguileras ex to help to revive her career

first_imgSinger Christina Aguilera reportedly wants former husband and music executive Jordan Bratman to help her revive her music career. The Your body hitmaker, who gave birth to daughter Summer Rain – her first child with fiancé Matthew Rutler last month, has reportedly reached out to Bratman, with whom she has son Max, 6, for advice for her next album.last_img

244 new CCTV cams to be set up to bolster security at

first_imgKolkata: In a bid to further intensify security in the state secretariat Nabanna, a step has been taken to install 244 more CCTV cameras.With installation of the new CCTV cameras, the total number of CCTV cameras will increase to around 400. At present, there are 150 CCTV cameras installed in and around the state secretariat. Sources said that the work to install the 244 cameras has started and will be completed at the earliest.According to a senior officer, the step to set up the new CCTV cameras has been taken to bring each and every place in and around the state secretariat under the coverage of surveillance cameras. Also Read – Heavy rain hits traffic, flightsThe CCTV cameras will be installed both inside and outside the building. More CCTV cameras will be installed in most of the floors of the state secretariat. At the same time, some of the cameras will also be installed at the area where cars of different officials are parked. The number of CCTV cameras in the area where cars of visitors are parked will also be increased. An official said that the work will be carried out at such a pace that it gets completed as early as possible. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedNabanna houses the office of Chief Minister Mamata Banerjee and some of her cabinet colleagues. Offices of senior officers of the state government including the Chief Secretary, Home Secretary and Director General of Police, are also in Nabanna. Several VVIPs from across the world also visit Nabanna regularly. So, the step of strengthening the security arrangement has been taken. The concerned officials had surveyed the building and identified the places where the CCTV cameras need to be installed. Based on the survey, the work of installing the CCTV cameras will be carried out. Hundreds of people visit the state secretariat every day over various work and meet key government officials. It may be mentioned that a decision was also taken to set up separate dog squad, especially for security of the state secretariat. With setting up of the dog squad, there will be a separate team for the security of Nabanna.last_img read more

Communalism has no place in West Bengal CM

first_imgKolkata: West Bengal Chief Minister Mamata Banerjee today said communalism has no place in the state which believes in unity in diversity. The chief minister said this on the occasion of the World Day for Cultural Diversity for Dialogue and Development.”Today is World Day for Cultural Diversity for Dialogue and Development. Our State Government has always believed in unity in diversity. Communalism has no place in the minds and hearts of the people of Bengal,” she tweeted this morning. Also Read – Heavy rain hits traffic, flightsThe Day, observed annually, is a United Nations sanctioned international holiday for the promotion of diversity issues.West Bengal had witnessed a few incidents of “communal clashes” in places such as Dhulagarh in Howrah district in 2016, and in Asansol and Raniganj, in March this year.The chief minister then had dubbed the incidents as a local matter and not a communal problem.Banerjee has accused the BJP of stoking communal tension in the state to fan Hindutva ideology.Incidentally, an analysis of the data on the number of incidents of communal violence in different states in the country, tabled in Parliament by Minister of State (MoS) for Home Affairs Hansraj Gangaram Ahir on February 6, showed that such incidents had sharply increased in West Bengal over the past three years.last_img read more