Measurement precision beats standard quantum limit

first_imgFor physicists, measuring the precise magnitude of a physical quantity is a key to understanding quantum mechanics. However, there is a limit to how precise a measurement can be made, which is governed by quantum mechanical laws. Explore further A connection between quantum correlations and spacetime geometry 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 In search of a more precise measurement of quantum phases, researchers from the University of Science and Technology of China have demonstrated a new measurement method that relies on multi-photon entanglement and the interference effect it generates.“High resolution quantum phase measurements will help to measure other related physical parameters with high precision, such as time shift, distance, etc.,” physicist Fangwen Sun told PhysOrg.com. Sun is currently with the Optical Nanostructure Laboratory at Columbia University in New York.In their study, which is published in a recent issue of Europhysics Letters, Sun and his colleagues describe an experiment where they achieve a phase measurement precision that surpasses the standard quantum limit, and nearly reaches the Heisenberg limit. “The scheme can be generalized to high-photon-number states,” Sun said. “There is no fundamental obstacle to achieve the precision approaching the Heisenberg limit.”As the researchers explain, the standard quantum limit is not the ultimate limit for measurement precision of quantum phases. Using a technique called squeezed-state-based interferometry, previous studies have already surpassed the standard quantum limit. However, the Heisenberg limit is considered the ultimate limit. Although researchers have proposed a number of schemes to approach this limit, none have been realized due an effect called loss.“The standard quantum limit is achieved with a regular source of light such as a laser,” Sun explained. “It goes as 1/N1/2 for N photons. The Heisenberg limit goes as 1/N for N photons. It can be achieved with quantum sources of light that exhibit special entanglement properties.” But, he added, “It has been proven that the Heisenberg limit is the true quantum limit and cannot be surpassed.”In their experiment, the researchers designed a method that is not as sensitive to loss as the previous proposals, and so it has a higher probability of resulting in an extremely precise measurement. First, the physicists generated an entangled state by injecting a two-photon Fock state into a beam splitter. Then, the entangled photons traveled through a line of optical elements including a half-wave plate, interference filter, and phase shifter. At the end, the physicists used a recently developed method called quantum state projection to extract the phase information from the entangled photons. “It is the collective effect of all the photons that improves the precision,” Sun said, explaining why better photon entanglement results in higher precision measurements. “The higher entanglement, the more collective effect.”With their new measurement technique, the researchers achieved a phase measurement precision of 0.506 for a two-photon state and 0.291 for a four-photon state. By contrast, the precision values set by the standard quantum limit are 0.707 and 0.5, respectively. For comparison, the Heisenberg limit has values of 0.289 and 0.25, which are thought to be impossible to achieve.Nevertheless, the physicists hope that, with anticipated improvements in technology leading to more efficient multi-photon detectors, the measurements might yield even more precise results. More information: Sun, F. W.; Liu, B. H.; Gong, Y. X.; Huang, Y. F.; Ou, Z. Y., Guo, G. C. “Experimental demonstration of phase measurement precision beating standard quantum limit by projection measurement.” Europhysics Letters, 82 (2008) 24001. Copyright 2008 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. Citation: Measurement precision beats standard quantum limit (2008, April 21) retrieved 18 August 2019 from https://phys.org/news/2008-04-precision-standard-quantum-limit.htmllast_img read more

MtDNA tests trace all modern horses back to single ancestor 140000 years

first_imgTwo young Nokota mares. Image: Wikipedia. Most other domestic animals such as cows, sheep and goats by contrast appear to have evolved from a relatively small pool, likely shortly before horses followed suit.Interestingly, horses appear in cave art as early as 30,000 years ago, which suggests that early humans certainly knew about them and likely killed them for food for twenty thousand years before the idea of taming them came about which ultimately led to domestication.To trace back the horse’s lineage, the research team tested mitochondrial DNA (which is passed down only on the mother’s side) samples from modern horses living in the Americas, Europe, Asia and the Middle East. This allowed them to follow the genetic line from the single mare to the eighteen gene clusters that show that people in several different places learned to domesticate horses and to use them for their own specific purposes. Previous researchers looking into horse lineage had used only a portion of DNA known as the control region, which wasn’t enough to provide a complete profile.Prior to this new research many scholars had attributed the first domestication of the horse to the Eurasian Steppes, due to fossilized evidence showing horse domestication dating to around 3500 BC. This new research will undoubtedly cause new discussions in the community as a whole which will likely lead to new theories being developed to describe how so many different groups of people came to domestic horses in so many places. (PhysOrg.com) — For many years archeologists and other scientists have debated the origins of the domesticated horse. Nailing down a time frame is important because many historians view the relationship between man and horse as one of the most important in the development of our species. Horses allowed early people to hunt for faster prey, to wander farther than before and to create much bigger farms due to pulling plows. Now, new evidence has come to light suggesting that all modern horses, which are believed to have been domesticated approximately 10,000 years ago, descended from one mare around 140,000 years ago. The new evidence comes from a team made up of international researchers who, as they describe in their paper published in the Proceedings of the National Academy of Sciences, say that DNA evidence shows that the horse subsequently diverged into 18 different genetic lines, suggesting that domestication occurred independently in many places throughout the world. © 2011 PhysOrg.com Citation: MtDNA tests trace all modern horses back to single ancestor 140,000 years ago (2012, January 31) retrieved 18 August 2019 from https://phys.org/news/2012-01-mtdna-modern-horses-ancestor-years.html Explore furthercenter_img Ancient wild horses help unlock past Journal information: Proceedings of the National Academy of Sciences More information: Mitochondrial genomes from modern horses reveal the major haplogroups that underwent domestication, PNAS, Published online before print January 30, 2012, doi: 10.1073/pnas.1111637109AbstractArchaeological and genetic evidence concerning the time and mode of wild horse (Equus ferus) domestication is still debated. High levels of genetic diversity in horse mtDNA have been detected when analyzing the control region; recurrent mutations, however, tend to blur the structure of the phylogenetic tree. Here, we brought the horse mtDNA phylogeny to the highest level of molecular resolution by analyzing 83 mitochondrial genomes from modern horses across Asia, Europe, the Middle East, and the Americas. Our data reveal 18 major haplogroups (A–R) with radiation times that are mostly confined to the Neolithic and later periods and place the root of the phylogeny corresponding to the Ancestral Mare Mitogenome at ∼130–160 thousand years ago. All haplogroups were detected in modern horses from Asia, but F was only found in E. przewalskii—the only remaining wild horse. Therefore, a wide range of matrilineal lineages from the extinct E. ferus underwent domestication in the Eurasian steppes during the Eneolithic period and were transmitted to modern E. caballus breeds. Importantly, now that the major horse haplogroups have been defined, each with diagnostic mutational motifs (in both the coding and control regions), these haplotypes could be easily used to (i) classify well-preserved ancient remains, (ii) (re)assess the haplogroup variation of modern breeds, including Thoroughbreds, and (iii) evaluate the possible role of mtDNA backgrounds in racehorse performance. 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

Research group creates longer lived and more efficient quantum memory

first_img Spin waves are where the electronic spin of one atom is transferred to another and then to another and so on propagating through a group. In this new research, the team found that by embedding information in a spin wave, and then retrieving it later, they could take advantage of the time it takes for the propagation to occur all the way though all of the atoms, thus allowing for holding onto quantum state information for a specified period of time.To make this come about, the team built a magneto-optical trap that first slowed atoms down using a laser beam. Once slowed, the atoms were held steady using magnets in a vertical triangular trap. When a photon was introduced, it caused a spin that was propagated through the atoms, creating a spin wave. At the other end, another laser fired at the same frequency as the first but with the opposite polarization caused the spin to be converted back into a photon, which revealed the quantum state information that had been held first in the original photon, and then conveyed through the wave. Using this technique, the team found that they could hold on to the quantum state information for 3.2 milliseconds and that the process was between seventy one and seventy five percent efficient.What’s more, the team believes that if optical lattices were introduced into the trap, i.e. crossed laser beams with different frequencies, they could make the whole system even more efficient. They also believe that this new process could be used as a means for creating memory storage in an actual quantum computer. More information: Efficient and long-lived quantum memory with cold atoms inside a ring cavity, Nature Physics (2012) doi:10.1038/nphys2324AbstractQuantum memories are regarded as one of the fundamental building blocks of linear-optical quantum computation and long-distance quantum communication. A long-standing goal to realize scalable quantum information processing is to build a long-lived and efficient quantum memory. There have been significant efforts distributed towards this goal. However, either efficient but short-lived or long-lived but inefficient quantum memories have been demonstrated so far. Here we report a high-performance quantum memory in which long lifetime and high retrieval efficiency meet for the first time. By placing a ring cavity around an atomic ensemble, employing a pair of clock states, creating a long-wavelength spin wave and arranging the set-up in the gravitational direction, we realize a quantum memory with an intrinsic spin wave to photon conversion efficiency of 73(2)% together with a storage lifetime of 3.2(1) ms. This realization provides an essential tool towards scalable linear-optical quantum information processing.via Arstechnica 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. Quantum memory for communication networks of the future Journal information: Nature Physics (Phys.org) — One of the main sticking points to creating a true quantum computer capable of performing meaningful work, is the problem of storing quantum state information in memory. Recent efforts have resulted in highly efficient memory that lasted only a short time or low efficient memory that lasts longer. Now, a combined group of two teams, one from China and one from Germany, have come up with a way that appears to offer the best of both worlds. As they describe in their paper published in the journal Nature Physics, they found that they were able to store quantum information in atomic spin waves. Citation: Research group creates longer lived and more efficient quantum memory (2012, May 30) retrieved 18 August 2019 from https://phys.org/news/2012-05-group-longer-efficient-quantum-memory.html © 2012 Phys.Org Explore furtherlast_img read more

Scientists create purplewinged butterflies in six generations

first_imgThe team says engineers could use these findings when designing devices that tune color, trap light or steer light beams. Journal information: Proceedings of the National Academy of Sciences When the researchers examined the wings that had changed color, they discovered that the thickness of some of the scales had changed. This altered the wavelengths of light the wings reflected. They studied the wings of B. sambulos and B. medontias, which naturally have wings that reflect violet light, and found that some of their wing scales were similar in thickness to those that had changed in the purple-winged B. anynana. However, the types of scales that reflected violet light in B. sambulos and B. medontias were different from the type of scale that had changed in B. anynana.Monteiro’s team believe their experiment shows that butterfly wing colors can evolve very quickly and that natural selection could play an important role in the development of wing color. For example, butterflies could use wing color to identify other butterflies of the same species or to influence mate choice. Explore further (Phys.org) —Scientists have used selective breeding to create purple wings on the normally brown-winged butterfly Bicyclus anynana. Antonia Monteiro and her colleagues selected butterflies with wing scales that reflected light closest to the wavelengths that produce the color violet and bred them. After six generation of breeding, the researchers produced butterflies with wings that had changed structurally to reflect violet light. The research appears in the Proceedings of the National Academy of Sciences. Deciphering butterflies’ designer colors: Findings could inspire new hue-changing materials Bicyclus anynana before (left) and after (right) artificial selection efforts to produce butterflies with violet wing scales. After selective breeding, the butterflies displayed more violet color in the ground scales of their wings. Credit: Antónia Monteiro Citation: Scientists create purple-winged butterflies in six generations (2014, August 5) retrieved 18 August 2019 from https://phys.org/news/2014-08-scientists-purple-winged-butterflies.html The butterfly Bicyclus anynana before artificial selection to alter wing color. Credit: William Piel. After six generations of artificial selection, Bicyclus anynana developed violet ground scales in its wings while the cover scales remained brown. Credit: Antónia Monteiro More information: Artificial selection for structural color on butterfly wings and comparison with natural evolution, PNAS, Bethany R. Wasik, DOI: 10.1073/pnas.1402770111AbstractBrilliant animal colors often are produced from light interacting with intricate nano-morphologies present in biological materials such as butterfly wing scales. Surveys across widely divergent butterfly species have identified multiple mechanisms of structural color production; however, little is known about how these colors evolved. Here, we examine how closely related species and populations of Bicyclus butterflies have evolved violet structural color from brown-pigmented ancestors with UV structural color. We used artificial selection on a laboratory model butterfly, B. anynana, to evolve violet scales from UV brown scales and compared the mechanism of violet color production with that of two other Bicyclus species, Bicyclus sambulos and Bicyclus medontias, which have evolved violet/blue scales independently via natural selection. The UV reflectance peak of B. anynana brown scales shifted to violet over six generations of artificial selection (i.e., in less than 1 y) as the result of an increase in the thickness of the lower lamina in ground scales. Similar scale structures and the same mechanism for producing violet/blue structural colors were found in the other Bicyclus species. This work shows that populations harbor large amounts of standing genetic variation that can lead to rapid evolution of scales’ structural color via slight modifications to the scales’ physical dimensions. The butterfly Bicyclus medontias displays violet-colored wing scales that evolved through natural selection. Credit: Antónia Monteiro Living things can produce color chemically or structurally. Those that produce chemical color create pigments that absorb certain wavelengths of light and reflect others. Organisms that produce structural color experience changes in their bodies, at the nanoscale level, that enhance the reflection of particular wavelengths.Butterfly wings have structural color. To understand how this color evolves, Monteiro and her team selectively bred B. anynana, a butterfly that normally has brown wings, in an attempt to create purple wings. Two close relatives of this butterfly, B. sambulos and B. medontias, have purple scales on the backs of their front wings. However, until now, no one has ever reported seeing any purple-winged B. anynana.To create purple wings, the team measured the wavelengths of light reflected from the wings of B. anynana specimens. They then selected and bred those butterflies whose wings reflected light closest to the violet spectrum. They performed this process six times in eight consecutive generations. As the breeding process continued, reflected wavelengths moved further toward the violet spectrum. By the sixth time, the butterflies had purple wings. © 2014 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

BJP protests against Bengal political killings

first_imgNew Delhi: The Delhi unit of the BJP on Monday protested against the West Bengal government over the killings of party workers and leaders in the state. Hundreds of Delhi Bharatiya Janata Party (BJP) workers staged a protest outside Banga Bhawan here and raised slogans against West Bengal Chief Minister and Trinamool Congress chief Mamata Banerjee. The party workers also carried placards reading ‘stop political killings against RSS-BJP workers’, ‘stop political violence in Bengal’ and ‘why silence on Bengal political violence’. South Delhi MP Ramesh Bidhuri told IANS: “Mamata Banerjee is plotting the murder of BJP and RSS (Rashtriya Swayamsewak Sangh) workers,” adding it is being done to terrorise the people of the state. He also said that this year, over 20 people have died in West Bengal since Panchayat elections and slammed leaders of other parties over their silence on the issue.last_img read more

42yearold held for assaulting minor

first_imgKolkata: A 42-year-old man has been arrested for attempting to rape a minor girl in his locality. The incident occurred at Tilajala on Thursday evening.According to police, the accused, Seikh Riazuddin, lured the victim with various promises and took her to his house. He tried to sexually assault the minor. The girl, however, was saved in due time as she screamed out for help, which immediately prompted the locals to come toher rescue.The victim has alleged that the man tried to touch her inappropriately, which left an injury mark on Also Read – Rain batters Kolkata, cripples normal lifeher body.The victim later fell ill and she was rushed to Calcutta National Medical College for treatment. The incident also triggered tension in the locality with locals staging a demonstration demanding stern action against the accused.The victim’s family members lodged a complaint at the local police station on Thursday night on the basis of which police have arrested Riazuddin on Friday morning.It was learnt that medical tests have confirmed that the girl was assaulted physically. The accused has been booked under Pocso Act.The victim girl is stated to be in a stable condition, the hospital sources said.The accused has been remanded to police custody after being produced before a court in the city.last_img read more

Heavy rainfall predicted

first_imgKolkata: A fresh low-pressure area that has been created over North Odisha and adjoining Bengal would bring moderate to heavy rainfall in various parts of the state, the Regional Meteorological Centre at Alipore predicted. However, the city may receive light to moderate rainfall in the next three days while some districts will witness heavy to very heavy rain. North-Eastern states are expected to see moderate rains in the next few days. States like Jharkhand, some parts of Bihar and Sikkim may also witness light to moderate rains. According to a senior weather official, the low pressure which was currently situating over North Odisha and adjoining parts of Bengal has gained some strength as a result of which various districts — both in North and South Bengal — will receive moderate to heavy showers depending on their geographical locations.last_img read more

High Court stays order on eviction of hawkers in Sector V

first_imgKolkata: The state government on Monday informed the Calcutta High Court that hawkers in Salt Lake Sector V area will be relocated elsewhere only after the state has a hawker policy in place. Soon after hearing the state’s stand, the High Court stayed the process of evicting the hawkers encroaching upon the bus route of Sector V till August 30. The stay of Justice Debangshu Basak came in the wake of the Salt Lake Sector V Hawkers’ Welfare Association, moving the high court against the eviction order. Also Read – Rain batters Kolkata, cripples normal lifeThe next hearing in this regard will be held on August 23. The counsel appearing on behalf of the state claimed that the government is absolutely against forcible eviction and wants proper rehabilitation of the hawkers. Hawkers in Salt Lake Sector V were taken to two plots of land in the area on Saturday where the Nabadiganta Industrial Township Authority plans to relocate them. It may be mentioned that police wants the hawkers on Ring Road, the stretch from the SDF intersection in GN Block to Technopolis building to be vacated for smooth traffic movement. It may be mentioned that hawkers in Sector V had demonstrated by keeping their shops closed on Friday to protest the order asking them to clear three main thoroughfares or face eviction. They also allegedly prevented several delivery persons of app-based food delivery services on their way to offices in Sector V.last_img read more

Mango extravaganza

first_imgIt is a three day extravaganza aiming to represent Delhi as a perfect tourist destination by showcasing and promoting its cultural and culinary diversity. The fest will be celebrating the irresistible fruit – mango, while also encouraging the cultural importance of Mangoes associated with Delhi. The celebration will continue for the three days of the fest.The festival will be inaugurated by Arvind Kejriwal, Chief Minister of Delhi in the presence of Manish Sisodia, Dy. Chief Minister, Delhi and Kapil Mishra, Minister for Tourism, Delhi. The fiesta will see a grand opening with artists from all over the country performing on stage and mascots dressed up in different costumes, giving it an extravagant look. Various summer fruit cultivators, product manufacturers, sharbat and dessert manufacturers and distributors  from different regions of the country will be a part of this grand event.  Also Read – ‘Playing Jojo was emotionally exhausting’The venue, Dilli Haat, Janakpuri corresponds to the essence of the fete. It is a multi-purpose, socio-cultural complex with a bazaar-like feel to it. It is an urban version of the traditional weekly market, with a delightful mix of craft, cuisine and culture. The Delhi Summer Festival is the perfect spot for all foodies to treat their taste buds with various summer fruits, thirst quenchers, desserts and much more.It will not only be a visual and mouth-watering treat, but also a jubilation of summer with taste and fun. Guests will see stage performances by ‘Twirls & Thumkas’ enacting a parade act along with other artists like Abhijit Ganguly, a comedian, Abhishek Acharya, an illusionist, Pratyul Joshi, a musician. These performances will be conducted throughput the event. Various amateur bands, singers, musicians have also been invited to perform at the gala.  Also Read – Leslie doing new comedy special with NetflixGuests will also get to attend interactive classes where recipes of yoghurt, sharbats, smoothies will be taught.Several competitions will make sure the visitors make the most out of the Summer Fest. A unique initiative ‘100 ka hai daam, kitne bhi khao Aam’ has been taken by the organizers in which the visitors have to pay only Rs.100 per entry and can eat mangoes at their heart’s desire. ‘Hangout’ is an exclusive jungle-themed entertainment centre, furnished with various games and activities to keep the children engaged.last_img read more

Ultadanga housewife murder Hotel manager held from Jharkhand

first_imgKolkata: One more person identified as Jaydev Yadav has been arrested in connection with the murder of Ultandanga housewife Archana Palangdar and her lover Balaram Keshri.He was arrested on Saturday night and was brought to Kolkata and produced before a city court on Sunday. Jaydev has been remanded to police custody till December 27. Sources informed that Jaydev used to be the manager of the hotel where Archana and Keshri stayed. After the murder case came to light, Jaydev Also Read – Rain batters Kolkata, cripples normal lifefled Kolkata. During investigation, the sleuths came to know that both Archana and Keshri’s body were removed from the hotel using an app cab. An employee identified as Ashis Yadav loaded the bodies in the cab with assistance from two other people identified as Harihar Mahato and Yadu Prasad. All of them were arrested during an investigation. During interrogation of Ashis, the sleuths came to know about Jaydev’s involvement. According to the sources, Jaydev being the manager of the hotel had asked Ashis to dispose of the bodies overnight. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killedAshis then booked an app cab and did as he was directed by Jaydev. On sensing danger, Jaydev vanished from Kolkata. After sleuths came to know about Jaydev’s involvement, they tried to locate him but failed. Recently, with the help of the mobile phone tower location tracking system, police got information that Jaydev was hiding in Jharkhand. A few days ago, police became sure of his location and sent a team to Jharkhand for arresting Jaydev. On Saturday night, the police team successfully nabbed Jaydev and brought him to Kolkata. Archana and Keshri were found dead inside a hotel room on September 19. Later, Archana’s body was dumped in a canal near Chowbaga pumping station and Keshri’s body was dumped at Nonadanga adjacent to Eastern Metropolitan (EM) Bypass. On September 20, Archana’s body was fished out of the canal and a few days after, police were able to recover Keshri’s body. Later, cops came to know about the New Market hotel where they had stayed. During an investigation, the sleuths arrested several persons connected to the hotel and came to know that Keshri murdered Archana over some conflict and committed suicide. However, police are not believing the story narrated by them. It is expected that after Jaydev’s interrogation, a detailed information related to the murder case would be revealed.last_img read more