Quantum eavesdropper steals quantum keys

first_img ‘Dead time’ limits quantum cryptography speeds (PhysOrg.com) — In quantum cryptography, scientists use quantum mechanical effects to encrypt and then communicate confidential information. Although quantum cryptography codes are unbreakable in principle, even the best techniques have loopholes in practice that scientists are trying to address. In a recent study, physicists have exposed one of these loopholes by hacking a quantum code, which involved copying a secret quantum key without being detected. 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. Citation: Quantum eavesdropper steals quantum keys (2011, June 20) retrieved 18 August 2019 from https://phys.org/news/2011-06-quantum-eavesdropper-keys.htmlcenter_img The researchers, Ilja Gerhardt, et al., from the National University of Singapore and the University of Trondheim, have published their study in a recent issue of Nature Communications. Although this is not the first experiment to show that quantum cryptography systems are vulnerable and that a quantum key can be secretly copied, it is the first time that someone has actually copied a quantum key.“This confirms that non-idealities in physical implementations of QKD [quantum key distribution] can be fully practically exploitable, and must be given increased scrutiny if quantum cryptography is to become highly secure,” the scientists wrote in their study.In the quantum cryptography technique explored here, the secret key is the tool that the sender and receiver (“Alice” and “Bob”) use to encode messages. For instance, Alice can send a key in the form of polarized single photons to Bob. Alice randomly polarizes the photons using either a horizontal-vertical polarizer or a polarizer with two diagonal axes. Bob also randomly uses one of the two different polarizers to detect each photon. Then, Bob asks Alice over an open channel which polarizer she used for each photon and compares them to his measurements. The measurement results for which Bob used the correct polarizer now become Alice and Bob’s secret key.In order to copy this key and intercept a message, an eavesdropper (“Eve”) would have to correctly guess which polarizer to use on every photon that Alice sends Bob. Due to the large number of photons used, it’s unlikely that Eve could choose correctly for very long. When Eve uses an incorrect polarizer, the photon’s polarization is randomized, which makes Bob’s measurement incorrect. This error alerts Bob and Alice to an eavesdropper’s presence, which they can confirm by comparing a small subset of the key on an open line.In the new study, the physicists showed how to steal the quantum key without being detected in an experiment on a 290-meter-long fiber link at the National University of Singapore. First, they intercepted single photons traveling along the fiber, and then re-emitted bright light pulses with the same polarization to “blind” the photodioides that Bob uses to detect photons.When blinded, Bob’s photodiodes cannot detect single photons, but instead they respond to the intensity of incoming light pulses. For this reason, Bob can no longer randomly choose a polarizer for each measurement. In their experiment, the researchers intercepted more than 8 million photons in a five-minute span, and then re-emitted corresponding bright pulses; Bob correctly measured all of these bright pulses in the correct detector. So if Alice and Bob were to compare the subset of the key, there would be no errors, and no hint of an eavesdropper on the line.Now that they have shown how to steal a quantum key without detection, the scientists are working on preventing these attacks from happening and making quantum cryptography more secure. One possibility is for Bob to set up a single-photon source in front of his detectors and randomly switch it on just to make sure that his detectors can still register single photons. If not, the detectors may have been “blinded” by an eavesdropper. © 2010 PhysOrg.com More information: Ilja Gerhardt, et al. “Full-field implementation of a perfect eavesdropper on a quantum cryptography system.” Nature Communications, Volume: 2, Article number: 349, DOI: 10.1038/ncomms1348via: Physics Worldlast_img read more

Read More »

Simulation shows colloids can form into noncrystalline state at below freezing temperatures

first_img More information: Liquids more stable than crystals in particles with limited valence and flexible bonds, Nature Physics (2013) doi:10.1038/nphys2693 . www.nature.com/nphys/journal/v … /full/nphys2693.html On ArXiv: arxiv.org/pdf/1307.1842.pdfAbstractAll liquids (except helium owing to quantum effects) crystallize at low temperatures, forming ordered structures. The competition between disorder, which stabilizes the liquid phase, and energy, which leads to a preference for the crystalline structure, inevitably favours the crystal when the temperature is lowered and entropy becomes progressively less relevant. The liquid state survives at low temperatures only as a glass, an out-of-equilibrium arrested state of matter. This textbook description holds inevitably for atomic and molecular systems, where particle interactions are set by quantum-mechanical laws. The question remains whether it holds for colloidal particles, where interparticle interactions are usually short-ranged and tunable. Here we show that for patchy colloids with limited valence, conditions can be found for which the liquid phase is stable even in the zero-temperature limit. Our results offer fresh cues for understanding the stability of gels and the glass-forming ability of molecular network glasses. © 2013 Phys.org Citation: Simulation shows colloids can form into non-crystalline state at below freezing temperatures (2013, August 7) retrieved 18 August 2019 from https://phys.org/news/2013-08-simulation-colloids-non-crystalline-state-temperatures.html Phase diagram of tetrahedral coordinated patchy colloids for different patch widths. Credit: arxiv.org/abs/1307.1842v1 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. Journal information: Nature Physicslast_img read more

Read More »

Researchers find migration risks likely led to drab colored female birds

center_img Being more colorful found to be disadvantage for female plover More information: Migration and the evolution of sexual dichromatism: evolutionary loss of female coloration with migration among wood-warblers, Proceedings of the Royal Society B, Published 27 May 2015 DOI: 10.1098/rspb.2015.0375 Journal information: Proceedings of the Royal Society B It is common knowledge that many birds of the same species look radically different, males often sport bright colors or fancy feathers, all designed to help them find a mate. Females, because they are generally the target of such pursuit and can pick and choose from many males, quite often are less colorful. But not in all cases—the researchers noted that in some species color dimorphism was quite pronounced in some parts of North America and barely noticeable in others, and wondered why there was a difference. They noted that it appeared to be based on latitude, female wood—warblers, for example that live in the south, tended to be nearly as colorful as the males, while those that lived up north tended to be far more drab. But could it all be chalked up to location? The researchers were not so sure so they poured over prior research studies of the birds focusing on ancestry, migration patterns, coloring and breeding locales of 109 of the warbler species.They used the data they compiled to test three hypotheses—two of which suggested the differences in coloring were due to migration—one based on the cost due to risk from predators the other to simple relaxation of natural selection. The third considered whether the differences in coloring of females had anything to do with the coloring of the males.In the end, the first theory held out, gender coloring differences were most pronounced based on migration distances, which suggested that females have less coloring because it makes them less visible to predators during their annual migrations, or as the authors note, the loss of female coloring appeared to be a driver of dimorphism, which implies that at least for wood-warblers, social and/or natural selection may be a stronger force for variation than sexual selection.last_img read more

Read More »

Testing of soil water compartmentalizing indicates it is widespread among many biomes

first_img(Phys.org)—A trio of researchers with the University’s of Saskatchewan and Calgary, both in Canada has found evidence that backs up a theory that has suggested that soil water is compartmentalized. In their paper published in the journal Nature, Jaivime Evaristo, Scott Jasechko and Jeffrey McDonnell describe how they carried out their study and their surprising results. Journal information: Nature Explore further Citation: Testing of soil water compartmentalizing indicates it is widespread among many biomes (2015, September 3) retrieved 18 August 2019 from https://phys.org/news/2015-09-soil-compartmentalizing-widespread-biomes.html © 2015 Phys.org Credit: Mick Lissone/public domaincenter_img More information: Global separation of plant transpiration from groundwater and streamflow, Nature 525, 91–94 (03 September 2015) DOI: 10.1038/nature14983AbstractCurrent land surface models assume that groundwater, streamflow and plant transpiration are all sourced and mediated by the same well mixed water reservoir—the soil. However, recent work in Oregon1 and Mexico2 has shown evidence of ecohydrological separation, whereby different subsurface compartmentalized pools of water supply either plant transpiration fluxes or the combined fluxes of groundwater and streamflow. These findings have not yet been widely tested. Here we use hydrogen and oxygen isotopic data (2H/1H (δ2H) and 18O/16O (δ18O)) from 47 globally distributed sites to show that ecohydrological separation is widespread across different biomes. Precipitation, stream water and groundwater from each site plot approximately along the δ2H/δ18O slope of local precipitation inputs. But soil and plant xylem waters extracted from the 47 sites all plot below the local stream water and groundwater on the meteoric water line, suggesting that plants use soil water that does not itself contribute to groundwater recharge or streamflow. Our results further show that, at 80% of the sites, the precipitation that supplies groundwater recharge and streamflow is different from the water that supplies parts of soil water recharge and plant transpiration. The ubiquity of subsurface water compartmentalization found here, and the segregation of storm types relative to hydrological and ecological fluxes, may be used to improve numerical simulations of runoff generation, stream water transit time and evaporation–transpiration partitioning. Future land surface model parameterizations should be closely examined for how vegetation, groundwater recharge and streamflow are assumed to be coupled. 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. Tracing nitrate in watersheds Common sense suggests that when it rains, water makes its way down into the soil—some of it is pulled into plants, some evaporates and some makes its way to rivers or streams or down into the water table—in a fairly uniform way. But now it appears that is not exactly the case, the results of fieldwork done by the team in Canada show that water is actually segregated between evaporation and transpiration in some soil areas and groundwater and streams in others—and it appears to be widespread among many types of biomes.As the researchers note, recent work by teams conducting studies in Oregon and Mexico suggested that water compartmentalizing was occurring, but the idea had not been tested. They sought to do that themselves to find out if water really does segregate naturally because if it does, that would likely have a big impact on water management schemes. To test the idea, they checked soil samples from 47 different sites for hydrogen and oxygen isotopic levels. That allowed them to see that many plants use water in the soil that is not part of the water that makes its way into streams and groundwater reservoirs—very clearly suggesting compartmentalizing. They also discovered that 80 percent of their samples showed that water from precipitation that would up in groundwater and streams, was different from precipitated water found in soils that plants were using, also clearly indicating compartmentalizing.What the researchers still do not understand, however, is the nature of the compartmentalizing—does water exist in tiny channels bound for an underground reservoir, for example, right near a plant that is dying of thirst due to a lack of water in the soil around them? The researchers do not know, but theorize that it is possible that water from different types of storms behaves differently once it hits the ground. More work will have to be done to better understand what is really going on.last_img read more

Read More »

Young adults are always curious about sex

first_imgMy daughter is seeing a guy from a different religion. She’s in college and refuses to end the relationship despite us asking her to. We hail from a very conservative Hindu family. We are very worried.Mrs. Modi, New DelhiAs parents you definitely have the right concerns. But, love knows no bounds. It doesn’t differentiate between color, creed or religion. As an adult, your daughter surely has an idea about her family and background. If she is in a relationship with a guy, I’m sure she understands the consequences. You can surely speak to her and explain your expectations and concern. But, in such cases the chance of letting the relationship go is minimal. Your family should mentally prepare itself to face the ‘unwanted’. Also Read – ‘Playing Jojo was emotionally exhausting’My son is 17 years old. A few days back I saw his cellphone loaded with porn clips. We are extremely shocked as he comes across as a very decent kid! How to speak to him about this?Neha Singh, ChandigarhAt his age, this is probably normal. Young adults are always curious about sex. As they have limited scope to explore and pornography is a vent. I request you not to worry about this and let him handle his fantasies and desire his way. Just be watchful about the company he keeps and be a good friend to him. Let him have a good journey towards manhood and treat him as an adult. Your boy is almost a man now and there’s nothing wrong about it! Also Read – Leslie doing new comedy special with NetflixIn a party last week, I saw my husband kissing a woman. She is our friend’s cousin. This has shocked me. But, I don’t observe any change in his attitude towards me. What should I do?Sarita, MPWas he under the influence of alcohol? In parties, sometimes we land up doing some things which in a normal situations we can’t even imagine! As a wife you have all the rights to question him about his act. You should let him know what you had seen and how you felt about it. There’s nothing wrong in a constructive confrontation. As a married couple, you both have certain responsibilities and decorum that need to be maintained. Have a polite talk, this will help you clear issues. My girlfriend insists on sex with condom. I hate it. How can I convince her to have it normally?Name unknownIt’s but natural that your girlfriend believes in ‘safe sex’. This protects both of you. Not only from unwanted pregnancy but from dreadful diseases as well. During her ‘safe period’ you can try unsafe sex, yet, even I would advise you to use condom as prevention is always better than cure!How safe is withdrawal sex? We practice unsafe sex but my boyfriend ejaculates outside. Please let us know.Pinky, ChandigarhWell, it’s not that it doesn’t work but then there are chances that it might not work some times. In today’s age you can choose from various options based on your choice. Pills, condoms are widely accepted and used. Suggest you play it safe as its good to be safe than sorry!Have a love or life query you cannot find an answer to? Send your questions to – [email protected]last_img read more

Read More »

4 dead in separate road accidents

first_imgKolkata: Four persons were killed and three others injured, some of them critically, in four separate road accidents that took place in the state since Friday night.Two bikers were killed after being mowed down by a speeding truck at Borgachia area near Berhampore in Murshidabad on Saturday morning. The incident occurred at around 9 am when a speeding truck hit two bikers, critically injuring them. They were rushed to Midnapore Medical College and Hospital for treatment where both the victims were declared brought dead. One has been identified as Rajab Ali while the other’s identity is yet to be confirmed. Both were residents of Naopukuria village under Beldanga police station. Also Read – Heavy rain hits traffic, flightsThe driver of the truck fled the spot along with the vehicle immediately after the accident. The locals staged demonstration at the accident site protesting against the reckless driving which often lead to serious accidents. The demonstration was later lifted following the intervention of senior police officers. Raids are being conducted by the district police to nab the truck driver.In a similar incident, 35-year-old Khokon Manna was killed when the motorcycle he was riding on was hit by a truck on Haldia-Mecheda Road on Saturday morning. He sustained critical injuries and died at Haldia sub-divisional hospital. The driver of the truck fled the spot along with the vehicle before the locals reached the spot. He was a resident of Baroj area of Haldia and was going to his work place when the fatal accident happened. The body has been sent for an autopsy. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedThe third accident took place at Kaligeria area of Kharagpur where a middle-aged man, identified as Muktipada Jana, was hit by a loaded truck while returning home from the market on his motor cycle. It happened on National Highway 60. An irate mob set a police vehicle on fire when they reached the spot to bring the situation under control. Police had to resort to lathi-charge to control the mob.Three persons including a pregnant woman were injured in a road accident at Mominpur area of the city on Saturday morning.last_img read more

Read More »

Faridkots second coming

first_imgThe band started out in 2008 and gained recognition with their two albums Ek (2011) and Phir Se (2014) with their third album currently in production. “This time we are looking to take our music to a different direction. We have already written a single, which is going to be a far cry from all our other songs as it will be predominantly a dance track. Our first album was instinctive and the second album was progressive so making the third is a challenge, but we have taken it head on”, Rajarshi stated. The single, Barsaat is due out next month. Also Read – ‘Playing Jojo was emotionally exhausting’Every band has a unique story on how it comes up with its name and Faridkot is not different. “It’s a rather silly story (laughs). IP Singh ( the lead vocalist) called me up one day and told me that he was thinking of a name for the band. I said the name doesn’t matter. Whatever you come up with will do. He replied that he saw the name Faridkot printed on a t-shirt and he wanted to keep that name. I was fine with it. So here we are with the name Faridkot”, Rajarshi explained. On asked about what exactly is a confused pop genre in music, he remarked that they did not want to be confined to only one kind of music. With the confused pop genre, they could experiment with everything and had a larger playing field. “At the end of the day we wanted to make good music and did not want to decide on the genre. We wanted to make music that the audience would like and with pop music acting as a representative of the society we live in, we got a wide array of possibilities,” he answered. Also Read – Leslie doing new comedy special with NetflixTalking about the Expendables 3 experience, Rajarshi was understandably excited. “It was a lot of fun. When we got the call, we didn’t think too much. We just said yes. In any event, we were sitting in the studio and doing nothing (laughs). It was a dream job for us. To make the title track of a movie starring superstars who we had only seen on TV and idolized growing up, was one of the best moments of our lives.”Phir Se, their second album got nominated for the Global Indian Music Academy Awards (GIMA) in the best rock album category. “We were on cloud nine. To get nominated with the likes of the Mekaal Hassan band was truly an honour. It was an amazing feeling which I cannot quite describe.” Rajarshi stated. On asked if they still get nervous before going up on stage, Rajarshi said,” We still do but a lot less than before. Every live performance has a different audience and you are playing your own original songs in front of them, hoping that they like them. It’s a new kind of nervousness where we feel kind of excited too. In any event, we try not to think about it too much (grins).Before signing off, Rajarshi had a message to all aspiring bands. “If you start out thinking that you will be huge, you probably won’t be able to make it. Keep making original music and keep rehearsing. For any kind of music, that is the challenge. If you persevere, you’ll go very far.”last_img read more

Read More »

Excellently Exhibited

first_imgThe Excellentia Equitation Centre recently conducted the ‘10th Excellentia Horse Show’ in the national Capital on September 26 and 27. The show which was sponsored by the Shri Balaji Society and saw a wide variation of equestrian competitions in the sport of show jumping and dressage ranging across all age groups and rite from beginner to advance levels. The first day saw competitions in dressage and events for children with 7 year-old Anmol Lehal being the youngest rider. While the second day witnessed competitions in Show Jumping with head constable Dharampal from Delhi police as the eldest rider in his late 50’s. Also Read – ‘Playing Jojo was emotionally exhausting’The grand finale, which was held under flood lights on 27th, saw an action-packed episode of show jumping along with a display of fencing conducted by the deuce academy Gurgaon. The event saw the presence of an eminent crowd with over 500 people present to witness the grand finale, also present were Special Commissioner of Police (Intelligence) Balaji Srivastava, Special Commissioner of Police (Provisions & Logistics) Sudhir Yadav as well as Lt. Gen Sudhir Sharma (retd.), ex-president of the equestrian federation of India among several other dignitaries. Also Read – Leslie doing new comedy special with NetflixThe show saw a massive participation with over 100 entries in the competition with teams such as Delhi Police, Genesis Global School Noida, Modern School Barakhamba, Army polo & Riding club, Adagio riding stables, Woodstock riding school as well as various other top riders such as Abhishek Chopra, Kirat Nagra, master Raunaq Anand and the current national champion and member of the Asian Games team Sehej Singh Virk, who also won the Ahiraan trophy for the best horse & rider combination of the event. The Excellentia Equitation Centre is one of the finest and most centrally located riding establishments in Delhi NCR, located just a few kilometers from the DLF Promenade Mall in Vasant Kunj. After the successful completion of the 10th edition of the horse show, the director Udai Singh (former member of the Indian Team) is very certain that the Excellentia Horse Show series, the only one of its kind in the north region, will attain greater success in times to come and further help in the overall development of this wonderful sport.last_img read more

Read More »