LCDs get brighter with nano polarization recycler

first_imgOn the left side of this drawing, P1 light is transmitted through the LCD panel, while a conventional bottom polarizer absorbs P2 light. On the right, the scientists’ new nano-wire grid polarizer recycles some of the otherwise-absorbed P2 light back to the light box, where it is partially converted to P1, and the process repeats. Image credit: Sang Hoon Kim et al. LCDs (liquid crystal displays) provide a popular method for lighting screens on everything from computers and TVs to watches, clocks, cell phones and more. However, as scientists Sang Hoon Kim, Joo-Do Park and Ki-Dong Lee from Korea report, the light efficiency of LCDs is below 10%. Realizing there’s room for improvement, the team developed a way to brighten LCDs by recapturing much of the lost light using a technique called polarization recycling. 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. Citation: LCDs get brighter with nano polarization recycler (2006, September 6) retrieved 18 August 2019 from https://phys.org/news/2006-09-lcds-brighter-nano-polarization-recycler.html Review: Motorola Moto G7 is the inexpensive Android phone you’ve been waiting forcenter_img In the past decade or so, a competition between LCDs and plasma screens has brewed for mainstream users, exciting as well as confusing many TV and computer buyers who want to own the best and latest technology. It’s pretty clear that LCDs, with their low power consumption, have won out for computer screens. For TVs, however, plasma screens have remained in the race largely due to their high quality in brightness and color contrast. If LCDs can improve in this area, it’s highly likely that they will dominate the TV market, as well.Kim, Park and Lee recently made a large step in enhancing the brightness of LCDs by taking a nano-wire grid polarizer (NWGP), a device known to reflect polarization, and inserting it between the LCD panel and backlight. “The problem with current LCDs is a low light efficiency,” Lee told PhysOrg.com. “Therefore, one needs more power to be supplied for light sources like LEDs or fluorescent lamps, or more light sources to be used in order to increase the brightness of LCDs. If one uses reflective polarizers like NWGP, one can get higher brightness in a given power consumption.”An LCD unit contains several thin films of glass and filters placed back-to-back, notably two polarizing films placed perpendicular to each other. In between these polarizers, liquid crystal molecules lie in a twisted helix, normally creating a lighted screen. However, typical polarizers transmit only some of the light from the light box, and absorb some light. Kim et al.’s new polarizer, on the other hand, reflects the otherwise absorbed light back to the light box so it can be transmitted again, effectively recycling the light polarization and increasing the brightness (see figure).“The amount of recycled polarization depends on the way the BLU [backlight unit] is constructed, said Lee. “In the paper, we assumed 0.5 percent in a single return after each reflection at the NWGP. Since non-converted light will reflect again and again by NWGP, the total conversion ratio should be calculated by summing the sequence. However, the actual ratio will be less than the number since some light will be lost by absorption.” One component of brightness in LCDs is overall light transmission. With their set-up, Kim and his colleagues achieved transmission above 90%, noting that a trade-off exists between transmission and contrast ratio, another parameter of brightness. Contrast ratio is the ratio of the luminosity of the lightest color to that of the darkest color a system produces. When an electric field is applied to the liquid crystals between the films, the crystals align with the electric field rather than the films, cutting off the light’s path and creating a dark spot on the screen. The closer to true black a display can reach, the higher its contrast ratio (complete black would result in an infinite contrast ratio). With higher light transmission, blocking all the light becomes more difficult, although the scientists found that the lighter colors that high transmission created outweighed the not-as-dark black in terms of overall brightness.“The contrast ratio used in the paper [which was 12.5] differs from the contrast ratio in a TV,” Lee explained. “The contrast ratio of NWGPs indicates the extinction ratio of the polarizer. It doesn’t determine the contrast ratio advertised for LCD TVs.”To build their nano-wire grid polarizer, the team used laser interference lithography to deposit aluminium onto a film. Using computer simulations, they found that maximum brightness enhancement is achieved with 20-nanometer-thick aluminium films deposited at a 50 degree angle on a nano-wire grid. Further, Kim and his team reported that their recycling polarizers can be fabricated by nanoimprinting for increased volume production, as well as be extended to larger surfaces.Citation: Kim, Sang Hoon, Park, Joo-Do and Lee, Ki-Dong. “Fabrication of a nano-wire grid polarizer for brightness enhancement in liquid crystal display.” Nanotechnology 17 (2006) 4436-4438.By Lisa Zyga, Copyright 2006 PhysOrg.com Explore furtherlast_img read more

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Light Source Lasts 12 Years No Electricity Needed

first_img Explore further SLAC makes ‘electron camera,’ a world-class tool for ultrafast science, available to scientists worldwide The material, dubbed “Litrosphere,” can cover a standard sheet of paper for a cost of about 35 cents, and comes in a variety of colors. It´s also flexible, and can take the form of either paint or injection-molded plastic. The material is not affected by the heat or cold, can withstand 5,000 pounds, and stays on constantly.According to the company’s patent, the material is based on betavoltaics and uses the radioactive gas tritium as the power source. The beta particles from the tritium radiation can be safely contained by phosphor-coated microspheres. Tritium has a half-life of about 12 years.MPK specializes in glow-in-the-dark paint and other glow products, although the new material does not need to be exposed to light in order to work. The company predicts that the technology could be used for light safety tape, lighted life rafts/flotation equipment, toys, sports/camping equipment, and bikes.”This has potential to save billions in energy costs world-wide,” said Steve Stark, MPK engineer. “Litroenergy surpasses all known available lighting options for cost/durability/reliability and safety.”Litroenergy has recently been added to the New Energy Congress’ (NEC) list of Top 100 Technologies (rank pending). However, its use will likely be limited to applications that don´t require a great deal of light.”The intensity is not very strong,” noted NEC member Richard P. George. “This is good enough for night illumination of rifle scopes, watches, and emergency signs, but it is not going to come anywhere close to matching the light output of or replace electric light bulbs (incandescent, fluorescent, LED, etc.) or kerosene lanterns.”There are also rumors that MPK may use similar technology as a power source in the future.”It´s not something the company is ready to talk publicly about yet, but they do have battery technology that would be of the same ilk: betavoltaic technology allowing continuous power for years in all battery applications, including automobiles,” said NEC member Sterling D. Allan. “They think they will be able to win the DoD [Department of Defense] contest for the $1 million prize for backpack battery tech.”More information: Litroenergy at Wiki DirectoryLitroenergy Patent Citation: Light Source Lasts 12 Years – No Electricity Needed (2007, December 13) retrieved 18 August 2019 from https://phys.org/news/2007-12-source-years-electricity.htmlcenter_img A company called MPK is designing a light source that will glow continuously for more than 12 years without any additional energy. 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

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BlackBerry Storm 2 coming soon w Video

first_img The Storm 2, from Research In Motion (RIM), is almost the same size and weight as its predecessor, but looks more up-to-date, with a brighter, sharper screen and more responsive interface. The disconcerting “crack” between the display and the keys has gone, as has the mechanical SurePress interface. This has been replaced by an electronic version, which is more accurate because it has three more activators beneath the screen to sense when you are pressing on it than the first generation BlackBerry had. © 2009 PhysOrg.com (PhysOrg.com) — RIM are soon to release their updated BlackBerry, the Storm 2 smart phone, with a more streamlined design and touch-sensitive buttons instead of the hardware buttons of the first version. Li-Air: Argonne opens new chapter in battery research (w/ Video) BlackBerry Storm 2 BlackBerry Storm 2center_img Explore further The touch keyboard has also been improved to make typing faster, and it still includes SureType, which predicts your entries and speeds up typing. In the old Storm, the screen moved as you typed, but in Storm 2 it stays still and there is electronic feedback instead of mechanical. The interface now allows multiple key presses, which facilitates typing combinations such as Alt/key or Ctrl/key.The inertial scrolling is also better, and more responsive to flicking than the first version. As with all BlackBerry models, the Storm 2 has all the expected messaging and email capabilities, but it also has Wi-Fi, which its predecessor did not. Pages load quickly, especially over Wi-Fi. Citation: BlackBerry Storm 2 coming soon (w/ Video) (2009, October 20) retrieved 18 August 2019 from https://phys.org/news/2009-10-blackberry-storm-video.html 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

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British team set to field test gigantic balloon and water hose geoengineering

first_img More information: via Guardian Most would agree that we do have a problem on our hands, the Earth is slowly growing warmer, threatening water and food supplies, if not eventually our very existence. Many question however, the wisdom of pumping aerosols into the atmosphere to reflect some of the sun’s heat back into space, rather than simply figuring out a way to stop adding more carbon emissions.The initial test of the plan is slated to be carried out next month in an undisclosed location. There the team will send up a smaller version of the eventual behemoth, somewhere around two thirds of a mile (about a kilometer) high. In this test, nothing but water will be squirted into the air, though some suggest they might also try something called low-level cloud whitening, which is where sea salt would be pumped up and then dispersed into the air to increase the reflectivity of clouds.If successful, the team would then set to work in constructing the actual product, a balloon that some say would have to be as big as Wembley stadium and would weigh as much as several double-decker busses (this is a British project after all). Then, the balloon would be sent aloft to a height of twelve miles or so (20 kilometers) carrying with it something akin to a very long garden hose. Once up, a mixture of sulphates and/or aerosols would be pumped up the hose and then into the air, which would then, theoretically start reflecting heat back out into space; saving us all in the process.If the mechanics of the project do eventually work as planned, there will likely be much debate about actually carrying out its mission, as some will undoubtedly be very much against carrying out a mission where no one really knows what might happen. Citation: British team set to field test gigantic balloon and water hose geo-engineering experiment (2011, September 2) retrieved 18 August 2019 from https://phys.org/news/2011-09-british-team-field-gigantic-balloon.html © 2011 PhysOrg.com (PhysOrg.com) — In what to some might seem almost ludicrous, (think Dr. Stranglove,) a British team of geo-engineers are set to launch a giant balloon a half mile into the sky pulling with it a water hose that will then spray water pumped from the ground, into the air. But this is only the beginning; the idea is to see if such a system is feasible. The real goal is to see if it might be possible to send such a giant balloon much higher, say twice as high as airplanes fly, so as to release aerosols into the atmosphere to mimic the impact volcanoes have when they erupt. That is to cause a planetary cooling effect, to offset the warming effect of all the carbon emissions still being pumped full time into air. And that’s not all, the project dubbed Stratospheric Particle Injection for Climate Engineering (SPICE), is being backed by the British government, via the Engineering and Physical Sciences Research Council.center_img CERN CLOUD research team adds new pieces to puzzle of cloud formation Explore further 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

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Study finds link between global warming and frog susceptibility to fungal disease

first_img Citation: Study finds link between global warming and frog susceptibility to fungal disease (2012, August 13) retrieved 18 August 2019 from https://phys.org/news/2012-08-link-global-frog-susceptibility-fungal.html © 2012 Phys.org Chytridiomycosis is a skin disease that occurs when frogs and other amphibians are attacked by the fungus Batrachochytrium dendrobatidis. The result is generally death as the frogs develop cysts under their skin and eventually die of cardiac arrest. The disease is believed to be responsible for the deaths of billions of amphibians worldwide and has led to the extinction of some species and has put others at risk.Suspecting that global warming is possibly accelerating the death toll of amphibians infected with mold spores from the fungus, the team tested 80 Cuban frogs in the lab. There they subjected both frogs and the fungus to various temperature tests.In one test, temperatures were held constant. In another, temperatures were set to correspond to the normal highs and lows that occur in the natural world. Then, to mimic what the researchers believe global warming has wrought, they caused unexpected highs and lows, creating a chaotic, variable temperature zone.The team found that when existing by itself, the fungus did best when exposed to cool even temperatures or when the temperature changes were regular. The frogs did best, of course, when temperatures mimicked their natural environment. What was different however was when the fungus was present on the frog’s skin. Under those conditions, the fungus did better and the frogs did worse when the temperature was varied and unpredictable. This suggests, the researchers say, that it’s possible that global warming, and associated temperature volatility, is accelerating the rate of amphibian deaths from Chytridiomycosis.They also suggest the reason frogs become more susceptible to Chytridiomycosis during times of unpredictable temperature changes is because the fungus is a simpler organism that can respond faster than frogs, meaning they can acclimate faster. Explore further (Phys.org) — A lot of studies are underway to try to find out what the impact of changing temperatures due to global warming will be on plants and animals. But few so far have been done to study the impact of the likely increase in the variability of weather patterns that are also expected to occur as the planet heats up. Once such group however, has been focusing on the impact of variable temperatures on amphibians and a fungal skin disease that has been killing a lot of them. The researchers, from Oakland University and the University of South Florida, have, as they write in their paper published in Nature Climate Change, found that Cuban tree frogs appear to be more susceptible to the fungal disease chytridiomycosis when temperatures vary, than when temperatures remain relatively constant. Fighting massive declines in frog populations with bacteria and fungicidescenter_img More information: Disease and thermal acclimation in a more variable and unpredictable climate, Nature Climate Change (2012) doi:10.1038/nclimate1659AbstractGlobal climate change is shifting the distribution of infectious diseases of humans and wildlife with potential adverse consequences for disease control. As well as increasing mean temperatures, climate change is expected to increase climate variability, making climate less predictable. However, few empirical or theoretical studies have considered the effects of climate variability or predictability on disease, despite it being likely that hosts and parasites will have differential responses to climatic shifts. Here we present a theoretical framework for how temperature variation and its predictability influence disease risk by affecting host and parasite acclimation responses. Laboratory experiments conducted in 80 independent incubators, and field data on disease-associated frog declines in Latin America6, support the framework and provide evidence that unpredictable temperature fluctuations, on both monthly and diurnal timescales, decrease frog resistance to the pathogenic chytrid fungus Batrachochytrium dendrobatidis. Furthermore, the pattern of temperature-dependent growth of the fungus on frogs was opposite to the pattern of growth in culture, emphasizing the importance of accounting for the host–parasite interaction when predicting climate-dependent disease dynamics. If similar acclimation responses influence other host–parasite systems, as seems likely, then present models, which generally ignore small-scale temporal variability in climate7, might provide poor predictions for climate effects on disease. A chytrid-infected frog. From Riders of a Modern-Day Ark. Gewin V. PLoS Biology Vol. 6, No. 1, e24 doi:10.1371/journal.pbio.0060024 Journal information: Nature Climate Change 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

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LG Electronics HMD patent sets sights on video viewing

first_img Explore further In the patent, “Head mounted display and method of outputting a content using the same in which the same identical content is displayed,” originally filed August 16, 2012, LG Electronics proposed its idea about using HMDs to provide video content. When the user is staring at the device, the HMD is inactive. When the user looks away from the device, the same content will appear before the user’s eyes. The device can generate a “buzz” when there is that point of the user switching from device to glasses for viewing.The patent, filed by LG Electronics in 2012, was assigned to the company earlier this week.”According to the present invention, a location state of a digital device may be determined based on eyes of a user who wears an HMD. The HMD of the present invention may further include an image photographing sensor configured to detect a position of the pupil of the user wearing the HMD and may be able to track eyes of the corresponding user using the image photographing sensor. Therefore, the location state of the digital device of the present invention may be determined based on whether a display unit of the digital device is located within a view angle region of the user wearing the HMD. In this case, the view angle region may include a region within a predetermined range corresponding to the eyes of the user wearing the HMD. In particular, according to the present invention, the location state of the digital device may include a third state in which the display unit of the digital device is located within the view angle region of the user wearing the HMD and a fourth state in which the display unit of the digital device is not located within the view angle region of the user wearing the HMD. Meanwhile, according to an embodiment of the present invention, a location state of a marker may be also determined based on the eyes of the user wearing the HMD in the manner mentioned in the above description.” Google Glass theft-protector is granted patent Citation: LG Electronics HMD patent sets sights on video viewing (2013, April 26) retrieved 18 August 2019 from https://phys.org/news/2013-04-lg-electronics-hmd-patent-sights.html (Phys.org) —Such a concept: outputting currently-displayed content of a user’s digital device to an HMD. But there is an added nuance where the video follows you no matter where you look. LG Electronics filed a patent for its head mounted display that can show you your video content even when you are looking away from your external device. Credit: USPTO © 2013 Phys.org More information: Patent: Head mounted display and method of outputting a content using the same in which the same identical content is displayedvia Engadget 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

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Honda demonstrates new technology to prevent cars hitting pedestrians w Video

first_img(Phys.org) —Honda Motor Company Ltd has posted a video on its website demonstrating new technology it’s developing to help prevent cars from running into pedestrians. Based on already existing vehicle-to-vehicle (V2V) network technology, the system called by Honda an advanced vehicle-to-pedestrian (V2P) safety system aims to warn both drivers and pedestrians carrying smartphones of a possible collision. V2P, like V2V uses the Dedicated Short Range Communications (DSRC) protocol as a means of communication. It’s implemented in hardware being developed by Honda. In essence it’s an automatic system of broadcast and receiving of information pertinent to drivers and pedestrians. The hardware carried by the pedestrian is embedded in a smartphone and constantly monitors the position of the person holding the phone (using already embedded GPS and accelerometer) and the direction they are heading. Similarly, technology embedded in a car notes the location of the car, its direction and speed—all while continuously listening for broadcast information from devices held by pedestrians. A computer in the car constantly analyses all of the available information and constructs virtual scenarios in real-time. When the system projects that a pedestrian is about to cross the path of the moving vehicle, a warning is flashed on a heads-up display device in the vehicle—a message is also sent to the pedestrian—that message information is converted to a sound similar to the noise a truck makes when backing up and a warning message that is displayed on the phone’s screen.Honda says that the technology can also let drivers know if the pedestrian is listening to music, talking on their phone or texting—all indications that the person is likely not paying full attention to his or her real-world surroundings. Also, they say the technology can be useful in multiple scenarios such as when an approaching pedestrian is hidden by other vehicles or when a car is backing up. They also report that they are developing similar technology for cars and motorcycles, warning both of the possibility of a collision. GM says almost-driverless cars coming by 2020 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. Explore further PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen Play Honda Demonstrates Advanced Vehicle-to-Pedestrian and Vehicle-to-Motorcycle Safety Technologies. Credit: Honda Other companies such as General Motors have also announced plans for implementing such systems in cars in the near future. Most such ventures are a part of single initiative being driven by the U.S. Department of Transportation. If the technology proves capable of saving lives, the DoT might insist that all cars sold in this country be equipped with such a system, provided they can get smartphone makers to opt in as well. Citation: Honda demonstrates new technology to prevent cars hitting pedestrians (w/ Video) (2013, September 4) retrieved 18 August 2019 from https://phys.org/news/2013-09-honda-technology-cars-pedestrians-video.html © 2013 Phys.orglast_img read more

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Carbon nanotube logic device operates on subnanowatt power

first_img Citation: Carbon nanotube logic device operates on subnanowatt power (2013, September 23) retrieved 18 August 2019 from https://phys.org/news/2013-09-carbon-nanotube-logic-device-subnanowatt.html Toward achieving one million times increase in computing efficiency The researchers, Michael L. Geier, et al., at Northwestern University in Evanston, Illinois, and the University of Minnesota in Minneapolis, have published their paper on the subnanowatt CNT logic in a recent issue of Nano Letters.”A modern-day integrated circuit has more than 1 billion transistors,” coauthor Mark C. Hersam, Professor of Materials Science and Engineering, Chemistry, and Medicine at Northwestern University, told Phys.org. “Consequently, the power dissipation per transistor needs to be very low in order for the entire circuit to have a reasonable power consumption. In fact, it is generally accepted that power consumption is the key limiting factor to achieving further increases in the complexity (i.e., number of transistors) in integrated circuits.”As the researchers explain, one of the biggest advantages of CMOS architecture is that it has intrinsically low power consumption. This benefit arises from the fact that, unlike other logic architectures, one of the two types of transistors (p-type or n-type) is turned off under steady state conditions in each logic gate in CMOS devices. In order to fully take advantage of this potential for extremely low power consumption, the p-type and n-type transistors need to have precisely tuned and well-separated threshold voltages, which are the voltage levels that determine whether the device is ON or OFF. So far, this issue of the threshold voltages has not been addressed, and the researchers here identified it as the key challenge limiting the realization of highly integrated CNT-based CMOS electronics.In their study, the researchers used a metal gate structure to achieve symmetric and clearly separated threshold voltages for p-type and n-type CNT transistors, resulting in the ultralow power consumption. In the static states, in which the device is either ON or OFF, power consumption is less than 0.1 nW. At the midpoint of the transfer state, when both p-type and n-type transistors are simultaneously in the ON state, the voltage reaches its peak at 10 nW. By connecting multiple CNT transistors in various configurations, the researchers demonstrated inverter, NAND and NOR logic gates. In the future, these gates can be integrated into complex circuits, where they can provide subnanowatt static power consumption along with the other advantages of CNTs, such as solution processability and flexibility.”We are now working on making more complicated circuits, where we will have substantially more transistors and cascaded logic gates,” Hersam said. “We also have an interest in combining carbon nanotubes with other emerging nanoelectronic materials in our lab (e.g., molybdenum disulfide [MoS2]).” © 2013 Phys.org. All rights reserved. Illustrations of (a) the CNT CMOS inverter and (b) a cross-section of an individual CNT transistor, including a 25-nm-thick Ni gate that enables ultralow power consumption. (c) Atomic force microscopy image of the CNT film morphology in the transistor channel region. Credit: Geier, et al. ©2013 American Chemical Society 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.center_img Journal information: Nano Letters (Phys.org) —Researchers have demonstrated a new carbon nanotube (CNT)-based logic device that consumes just 0.1 nanowatts (nW) in its static ON and OFF states, representing the lowest reported value by 3 orders of magnitude for CNT-based CMOS logic devices. The device could serve as a building block for large-area, ultralow-power CNT logic circuits that can be used to realize a variety of nanoelectronics applications. Explore further More information: Michael L. Geier, et al. “Subnanowatt Carbon Nanotube Complementary Logic Enabled by Threshold Voltage Control.” Nano Letters. DOI: 10.1021/nl402478plast_img read more

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Quantum 1 classical 0 Bell nonlocality universally confirmed in any large communication

first_img Fig. 4. The scheme of the proof of Theorem 1. (A) an initial protocol evaluating function f with bias 1/6, using Q qubits; (B) memoryless protocol, with the same bias, using Q2 qubits; (C) protocol P‾ using quantum correlations and Q2 qubits, with bias still about 1/6; (D) protocol P‾ gives small bias for any classical correlation Rc if Q2 is sufficiently smaller than C(f, 2/3). Harry Buhrman, H. et al. (2016) Quantum communication complexity advantage implies violation of a Bell inequality. Proc Natl Acad Sci USA 113 (12) 3191-3196. Fig. 3. Exchange of the information after simultaneous teleportations to reveal the path of the teleported system in a three-round protocol. After Alice’s teleportation measurement in the first round the state ended up in port 1. Then, Bob teleports each of the two ports from the array that he used in the previous round, obtaining the outcomes 2 and 3 for ports 1 and 2, respectively. Finally, Alice performs a teleportation measurement for each of her four ports, obtaining the outcomes 2,4,5,8 for the ports 1,2,3,4, respectively. A defines a path q to be a sequence of teleportation outcomes: q={i1,1 =1, i2,1 =2, i3,2 =4}. The last node of the path points to the system, whose outcome provides Bob’s guess. Recall that the measurements are performed at the same time, and the sequential multiround protocol consists only of the exchange of classical information obtained after teleportation. The latter is required to identify the last node of the path, which is used to make a guess about the value of the function. Harry Buhrman, H. et al. (2016) Quantum communication complexity advantage implies violation of a Bell inequality. Proc Natl Acad Sci USA 113 (12) 3191-3196. More information: Quantum communication complexity advantage implies violation of a Bell inequality, Proceedings of the National Academy of Sciences March 22, 2016 vol. 113 no. 12 3191-3196, doi:10.1073/pnas.1507647113 Related:1Asymptotic teleportation scheme as a universal programmable quantum processor, Physics Review Letters (2008) 101(24):240501, doi:10.1103/PhysRevLett.101.2405012Quantum teleportation scheme by selecting one of multiple output ports, Physical Review A (2009) 79(4):042306, doi:10.1103/PhysRevA.79.042306 (Phys.org)—The relationship between communication complexity problems, Bell nonlocal correlations and the advantage of quantum over classical strategies has long been recognized, but has been confirmed in only two problems. Recently, however, scientists at University of Cambridge, University of Amsterdam, CWI, QuSoft, Gdansk University, Gdansk University of Technology, Adam Mickiewicz University, and Jagiellonian University employed a two-part method based on port-based teleportation – a scheme of quantum teleportation where a receiver has multiple (N) output ports and obtains the teleported state by merely selecting one of the N ports1,2. The researchers used the quantum protocol based on the given communication complexity game to construct a set of quantum measurements on a maximally entangled state to show that any large advantage over the best known classical strategy makes use of Bell nonlocal correlations. In so doing, the researchers assert, they have provided the missing link to the fundamental equivalence between Bell nonlocality and quantum advantage. Moreover, their results have significant implications for classical information processing and the development of more efficient teleportation protocols. To establish the connection between communication complexity and the violation of a Bell inequality, the scientists had to devise two things: a systematic way of obtaining correlations from any quantum strategy, and a suitable Bell inequality which would be violated by these correlations. “A particular obstacle which we had to overcome was to find a way of dealing with strategies which involved multiple rounds of communication, since previous tools allowed us to address only the case of single round algorithms,” Strelchuk explains. “Our key insight was to utilize a port-based teleportation protocol, which overcame this limitation wonderfully.” Fig. 1. The structure of a single round of the protocol. Alice applies Ux to her system, which if followed by Bob’s unitary Uy. Bob has no information about the outcome of Alice’s port-based teleportation, iA1 , so he teleports each of his qudit* subsystems individually, obtaining iB1,1, iB1,2, …. Credit: Harry Buhrman, H. et al. (2016) Quantum communication complexity advantage implies violation of a Bell inequality. Proc Natl Acad Sci USA 113 (12) 3191-3196. (*a generalization of the qubit to a d-dimensional Hilbert space) , Physical Review A The paper also reports a simpler method for one-way communication complexity problems. “For one-way communication complexity problems – that is, where in order to compute the value of a function one party is allowed to send a single message to another – there is no need to use the heavy guns of port-based teleportation. Instead, we use a much simpler procedure called remote state preparation.” Quantum teleportation uses prior entanglement and forward classical communication to transmit one instance of an unknown quantum state. Remote state preparation (RSP) has the same goal, but the sender knows classically what state is to be transmitted.Relatedly, the paper describes potential approaches for devising a more efficient teleportation protocol or improving one of the existing ones based on more efficient methods of exhibiting the Bell nonlocality of quantum communication complexity schemes. “One potential pathway to improvement is to devise a more efficient teleportation protocol. Our central tool, the port-based teleportation protocol, uses a large entangled state to teleport with a high probability of success. Moreover, a teleportation protocol with higher probability of success which consumes less entanglement would result in even larger values of the ratio of the quantum value to the classical value of the Bell quantity – but at present, we don’t know if such protocols exist.”Finally, the new method does not cover the protocols with initial entanglement, which the researchers describe as paradoxical because protocols that use initial entanglement should be even more explicitly Bell nonlocal. “Interestingly, if the parties which solve a communication complexity problem are already entangled then it should be possible to devise a Bell inequality that will be violated by the correlations originated from the measurement statistics of the algorithm. However,” Strelchuk adds, “a technical requirement in our construction makes it inapplicable to this setting.” As a result, the scientists concluded that it is desirable to search for a method of demonstrating the Bell nonlocality of such protocols. “Devising a method of showing that quantum communication complexity advantage implies violation of a Bell inequality when parties share initial entanglement is highly desirable,” he acknowledges, “as it would not only prove the equivalence between these two areas at the highest possible level of generality, but it may also shed light on how we could take advantage of pre-shared entanglement to make algorithms more efficient.” Moving forward, Strelchuk says that the researchers want to focus on reducing the gap between classical and quantum communication complexity required for their results to hold. “This gap arises as a technical artifact in our proof,” he tells Phys.org, “and there seems to be no apparent reason why it should exist. Another promising direction to pursue is the development of novel teleportation protocols which would consume less entanglement and provide higher probability of success…and the latter direction is interesting in its own right. As witnessed by our results,” Strelchuk concludes, “the applications of new teleportation protocols often surpass their intended purpose and find uses in other unrelated areas of quantum information processing.” Journal information: Proceedings of the National Academy of Sciencescenter_img © 2016 Phys.org All quantum communication involves nonlocality 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. Several of the study’s results have implications for classical information processing. In one case, the paper reports that quantum correlations distinguish classical from quantum information theory in the context of more recent findings that quantum correlations can be used as a resource for a number of distributed information processing tasks, producing surprising results – specifically when applied to communication complexity. “There are several problems in computer science in which quantum algorithms outperform their classical counterparts,” Strelchuk points out. “Such algorithms make use of entanglement – a resource not available in classical information theory. In certain models of multiparty communication complexity – a scenario where many parties exchange messages to compute the value of some function—quantum algorithms may be exponentially more efficient; however, in some cases quantum algorithms do not offer any speedup. It is therefore important to investigate the problems for which it actually makes sense to use the quantum resources in order to achieve to improvements over the best possible classical algorithms.” Fig. 2. Constructing quantum measurements. A and B denote Alice’s and Bob’s local subsystems, respectively. Each measurement Mi, i =1, …, r2r−1 represents the square-root measurement in the port-based teleportation (12). Harry Buhrman, H. et al. (2016) Quantum communication complexity advantage implies violation of a Bell inequality. Proc Natl Acad Sci USA 113 (12) 3191-3196. Explore further Citation: Quantum 1, classical 0: Bell nonlocality universally confirmed in any large communication complexity advantage (2016, June 14) retrieved 18 August 2019 from https://phys.org/news/2016-06-quantum-classical-bell-nonlocality-universally.html Dr. Sergii Strelchuk discussed the paper, “Quantum communication complexity advantage implies violation of a Bell inequality,” that he and his colleagues published in Proceedings of the National Academy of Sciences. Two of the challenges the scientists faced were encountered in demonstrating that any large advantage over the best known classical strategy makes use of Bell nonlocal correlations, and in providing the “missing link” (in the form of a general connection) between a large quantum advantage in communication complexity and Bell nonlocality. “One conceptual issue was finding a procedure that converts any quantum strategy for a given communication complexity problem into a set of correlations – that is, probability distributions corresponding to the measurement outcomes during the protocol,” Strelchuk tells Phys.org. “If the quantum algorithm performance beats the best known classical algorithm, these correlations violate a specially tailored Bell inequality that certifies that we indeed make use of nonlocal correlations in our algorithm.” He adds that prior to their work, there were just a few instances of this conversion – and moreover, these only worked for very specific problems. “In this study we’ve found a universal method which works for any algorithm.”Another obstacle was using port-based teleportation to show that if the gap between quantum and classical communication complexity grows arbitrarily large, the ratio of the quantum value to the classical value of the Bell quantity becomes unbounded with the increase in the number of inputs and outputs. “The ratio of Bell quantities indicates the extent to which quantum strategies outperform their classical counterparts.” Strelchuk notes. “With the help of recently-discovered port-based teleportation we estimate this ratio and consequently connect two distinct notions: performance of a strategy for the communication complexity problem and violation of the Bell quantity.”last_img read more

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Theoretical quark fusion found to be more powerful than hydrogen fusion

first_img To learn more about subatomic particles, researchers at the Large Hadron Collider cause atoms to move at high speeds and then smash them into one another. Doing so forces the component parts of the atoms to be disassociated from one another allowing each to be studied. Those components, scientists have found, are called quarks. Prior research has also shown that when atoms in the collider smash into each other, sometimes the pieces that come apart collide with other parts, fusing them into particles called baryons. Prior work has suggested that energy is involved when quarks fuse together. In studying the properties of one such fusing, a doubly-charmed baryon, the researchers found that it took 130 MeV to force the quarks into such a particular configuration, but they also found that fusing the quarks together wound up releasing 12 MeV more than that. Intrigued by their finding, they quickly focused on bottom quarks, which are much heavier—calculations showed it took 230 MeV to fuse such quarks, but doing so resulted in a net release of approximately 138 MeV, which the team calculated was approximately eight times more than the amount released during hydrogen fusion. Since hydrogen fusion lies at the heart of hydrogen bombs, the researchers were quite naturally alarmed at their findings. So much so that they considered not publishing their results. But subsequent calculations showed that it would be impossible to cause a chain reaction with quarks because they exist for too short a period of time—approximately one picosecond—not long enough to set off another baryon. They decay into much smaller, less dangerous lighter quarks.The researchers point out that their work is still purely theoretical. They have not tried to fuse bottom quarks, though they note it should be technically feasible at the LHC should others find doing so a worthwhile experiment. (Phys.org)—A pair of researchers with Tel Aviv University and the University of Chicago has found evidence suggesting that fusing quarks can release much more energy than anyone thought. In their paper published in the journal Nature, Marek Karliner and Jonathan Rosner describe their theories surrounding the amount of energy involved when various types of quarks are fused together. Explore further Journal information: Nature Schematic depiction of quark-level exothermic fusion reactions ΛQΛQ′ → ΞQQ′N, where Q,Q′ ∈ {b, c}. Credit: (c) Nature (2017). DOI: 10.1038/nature24289 More information: Marek Karliner et al. Quark-level analogue of nuclear fusion with doubly heavy baryons, Nature (2017). DOI: 10.1038/nature24289AbstractThe essence of nuclear fusion is that energy can be released by the rearrangement of nucleons between the initial- and final-state nuclei. The recent discovery of the first doubly charmed baryon Ξ++cc , which contains two charm quarks (c) and one up quark (u) and has a mass of about 3,621 megaelectronvolts (MeV) (the mass of the proton is 938 MeV) also revealed a large binding energy of about 130 MeV between the two charm quarks. Here we report that this strong binding enables a quark-rearrangement, exothermic reaction in which two heavy baryons (Λc) undergo fusion to produce the doubly charmed baryon Ξ++ cc and a neutron n (ΛcΛc →Ξ++cc n ), resulting in an energy release of 12 MeV. This reaction is a quarklevel analogue of the deuterium–tritium nuclear fusion reaction (DT → 4 He n). The much larger binding energy (approximately 280 MeV) between two bottom quarks (b) causes the analogous reaction with bottom quarks (Λ Λb b→Ξbbn 0 ) to have a much larger energy release of about 138 MeV. We suggest some experimental setups in which the highly exothermic nature of the fusion of two heavy-quark baryons might manifest itself. At present, however, the very short lifetimes of the heavy bottom and charm quarks preclude any practical applications of such reactions.center_img Citation: Theoretical quark fusion found to be more powerful than hydrogen fusion (2017, November 6) retrieved 18 August 2019 from https://phys.org/news/2017-11-theoretical-quark-fusion-powerful-hydrogen.html LHCb experiment announces observation of a new particle with two heavy quarks © 2017 Phys.org 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

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