Physicists demonstrate 100fold speed increase in optical quantum memory

first_img In a new study, a team of physicists, Klaus Reim, et al., from the UK, US, and Canada has focused primarily on increasing the bandwidth of an optical quantum memory. The researchers have achieved data rates that exceed 1 GHz, which is more than 100 times greater than the speed of existing quantum memories. Although other areas still need improvement, these high-speed memories will likely form the basis of tomorrow’s photonic quantum information processors. In their experiments, the physicists use a hot cesium vapor cell as the storage medium. They overlap a signal pulse containing several thousand photons (the information) with a strong write pulse, and send both pulses together into the cesium vapor cell. The vapor induces a Raman interaction, mapping the signal pulse with the write pulse into a collective atomic excitation called a spin wave. This information can then be stored in the cesium vapor cell for 12.5 nanoseconds, after which the information is retrieved by sending a strong read pulse into the cell. The read pulse converts the spin wave into an optical signal that is measured by a detector. “There are a few steps that are required [to achieve high bandwidth], but the main approach is to use atoms with a higher energy storage state, and to apply more sophisticated control pulse methods,” coauthor Ian Walmsley of the University of Oxford told achieving bandwidths up to 1 GHz, the new quantum memory offers data rates that are an increase of a factor of more than 100 compared to current quantum memories, which are limited to a few megahertz. Moreover, the researchers noted that the bandwidth was limited only by the response time of the detector; theoretically, the quantum memory could be capable of even larger bandwidths. In addition, the method offers long coherence times of several microseconds. One area that still needs work is the overall efficiency, which was about 15%. The cesium vapor could store 30% of the incoming signals, half of which could later be retrieved. The researchers plan to improve the efficiency by changing the signal pulse’s attributes. The physicists also noted that this Raman-based quantum memory scheme can be broadly applied to other storage media besides hot cesium vapor, such as cold gases and solid-state systems. Also, in addition to quantum computing, quantum memories like this one will be important for quantum repeaters for long-distance communication. “Our plans are to demonstrate the operation of the memory at the quantum limit, using an external source of nonclassical light,” Walmsley said. “Challenges for the future in general are to increase the number of bits the memory can store and the readout efficiency of the memories to the point when they can be used in applications such as quantum communications links.” More information: K. F. Reim, et al. “Towards high-speed optical quantum memories.” Nature Photonics. Doi: 10.1038/NPHOTON.2010.30 ( — As with today’s computers, future quantum computers will require more than just quantum information processing; they will also require methods to store and retrieve the quantum information. For this reason, physicists have been studying different types of quantum memories, which are capable of controllably storing and releasing photons. However, these memories still face several challenges in areas including storage time, retrieval efficiency, the ability to store multiple photons, and bandwidth. Explore further In the optical quantum memory, a signal containing the information and a write pulse are sent together into a cesium vapor cell. The vapor turns the pulses into a spin wave, and the information can be retrieved by a read pulse that converts the spin wave into an optical signal. The memory can achieve data rates that exceed 1 GHz. Image copyright: K.F. Reim, et al. Long-distance quantum communication gets closer as physicists increase light storage efficiency by an order of magnitude Citation: Physicists demonstrate 100-fold speed increase in optical quantum memory (2010, April 1) retrieved 18 August 2019 from Copyright 2010 All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of 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

Researchers build selfrepairing systemic computer

first_img(—Computer scientists Christos Sakellariou and Peter Bentley working together at University College in London, have built a new kind of computer that runs instruction segments randomly, rather than sequentially, resulting in a computer than in theory, should never crash. Citation: Researchers build self-repairing “systemic” computer (2013, February 15) retrieved 18 August 2019 from One of the main reasons that computers crash is because of the way they execute instructions, i.e. sequentially. Code is written in a step-by-step fashion and the computer follows a counter that retrieves lines of code in the proper order, executing each one before moving on to the next. Problems come in when the counter becomes mixed up, or code that has been executed fails to return control so that the next line can be run. To get around that problem, the researchers in Britain have built a computer that doesn’t run sequentially at all. It runs chunks of information that is made up of both code and data, and does so in random fashion, removing the sequential processing problem. The result, they say, is a computer that is able to repair itself on the fly, and won’t theoretically ever crash.The whole idea is based on nature’s distributed error correction processing abilities as demonstrated by such brilliant constructs as the human brain. As people exist, they think, they react and respond. They do all manner of things, none of which occurs as the result of a sequential processer in a central part of the brain. Instead, things are done in a distributed manner, with different biological processors working on different things at the same time. To make this happen with a computer, the researchers built a Field Programmable Gate Array (FPGA) which is essentially a bit of electronics that serves as a sort of traffic cop. Its main job is to make sure that different segments or “systems” as the researchers call them, get called on, albeit, in random fashion, and to allocate a place for them to run. One of the benefits of such a system is that no system has to wait for another to finish before running, which means the computer can run several systems at the same time. Thus, the FPGA is a resource manager, though it also serves as the manager of information that flows between systems.Because the systems are independent of one another, there is no crash if one of them is unable to carry out its instructions. But better than, that, other systems can be introduced into the system whose purpose is to detect problems with other systems and rerun them if necessary, or to change them slightly, if need be, to allow them to complete their assigned tasks. In the computer world, that’s known as self-repairing code and it’s something many people would like to see in computers running in the real world. With this new computer, it’s been demonstrated that such a computer can be built. Explore further Parallel course: Researchers help ease transition to parallel programming More information: © 2013 ‘Blue screen of death’ as seen in Windows 8. Credit: Wikipedia 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

Study shows evolution does not always mean more diversification

first_img The researchers were studying pharyngognathy in spiny fish—where the jaw changes over time to allow bones in the throat to grind down hard shells for digestion—to discover whether such an evolutionary adaption always works out, because the downside of it is a smaller gape, which means feasting on smaller fish. They noted that most such species live in shallow marine environments alongside other species that do not have the grinding capability. The exception was cichlids, which live in tropical freshwater places, such as lakes.Overall, the researchers found that pharyngognathy generally led to fish that evolved into niches that favored hard-shelled fish faster than did other fish, and that may have contributed to the decline of such fish species in Lake Victoria. The Nile perch, a non-pharyngognathous fish was introduced into the lake back in the 1950s and since that time cichlid numbers have been dropping dramatically. Initially it was assumed that the decline was due to the perch eating or killing the various cichlid species, but now, the researchers have shown that it was most likely due to them being out-competed—they compared the feeding performance of Nile perch against cichlids and discovered that the gape of the perch was double that of the cichlids, and that the cichlids also took much longer to digest prey. Taken together, the physical differences have clearly put the cichlids at a serious disadvantage, allowing the perch to thrive while the cichlids have been essentially starving to death. Thus, the specialization that came about due to the evolutionary adaption meant to allow them to eat a broader range of fish, in the end led to far less diversification in at least one closed ecosystem. A young Nile perch. Credit: John Uhrig Journal information: Science Nile perch are known to prey on cichlids, but they also outcompeted fish-eating cichlids. Credit: Matthew McGee Nile perch are known to prey on cichlids, but they also outcompeted fish-eating cichlids. Credit: Matthew McGee Harpagochromis, “orange rock hunter,” is a beautiful predatory cichlid now found in low numbers in Lake Victoria, but maintained in captivity thanks to conservation-minded cichlid hobbyists. Credit: Matthew McGee Harpagochromis, “orange rock hunter,” is a beautiful predatory cichlid now found in low numbers in Lake Victoria, but maintained in captivity thanks to conservation-minded cichlid hobbyists. Credit: Matthew McGee © 2015 Explore further Harpagochromis, “two stripe white lip,” is an undescribed species of Victorian predator cichlid now extinct in the wild. Thanks to a partnership with the Lake Victoria Species Survival Program, we were able to use this species in our study. Credit: Matthew McGee Citation: Study shows evolution does not always mean more diversification (2015, November 27) retrieved 18 August 2019 from Hormones may help tiny African fish climb social ladder More information: M. D. McGee et al. A pharyngeal jaw evolutionary innovation facilitated extinction in Lake Victoria cichlids, Science (2015). DOI: 10.1126/science.aab0800ABSTRACTEvolutionary innovations, traits that give species access to previously unoccupied niches, may promote speciation and adaptive radiation. Here, we show that such innovations can also result in competitive inferiority and extinction. We present evidence that the modified pharyngeal jaws of cichlid fishes and several marine fish lineages, a classic example of evolutionary innovation, are not universally beneficial. A large-scale analysis of dietary evolution across marine fish lineages reveals that the innovation compromises access to energy-rich predator niches. We show that this competitive inferiority shaped the adaptive radiation of cichlids in Lake Tanganyika and played a pivotal and previously unrecognized role in the mass extinction of cichlid fishes in Lake Victoria after Nile perch invasion.Press release (—A small team of researchers with members from the U.S. and Switzerland has found an example of a fish that did not always benefit in the end from an evolutionary change. In their paper published in the journal Science, the team describes their study of cichlid fish species in Lake Victoria and other places, and the changes that led to their downfall in one ecosystem. Geerat Vermeij with the University of California offers a Perspectives piece on the work done by the group in the same journal issue. 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

Living through craft

first_imgIndia has a diverse and rich craft tradition. Indian craft traditions are reputed all over the world and admired for their beauty, design, utilities and above all intricacy of craft. The Indian Handicraft industry is showing continuous and steady growth rate every year. To give further impetus to this important segment and to empower the artisans and craft persons Central Cottage Industries Corporation of India Ltd. a Govt. of India Undertaking, Ministry of Textiles, has organized Craft of living – An exhibition cum sale of exclusive artefacts that started on  February 18,  and will go on till February 28. Also Read – ‘Playing Jojo was emotionally exhausting’The exhibition was inaugurated by A.Madhukumar Reddy, Joint Secretary, Ministry of Textiles Govt. of India on February 18 at the Central Cottage Industries Emporium, Jawahar Vyapar Bhawan, Janpath, in the Capital. The exhibition comprises of diversified products and a large variety of items such as Wooden Panel, Antique Oil Lamps and Tanjore Paintings from Tamil Nadu, Marble Artefacts, Wooden Painted Artefacts, Pichwai Paintings and Handcrafted Furniture from Rajasthan, Dhokra Artefacts from Chhattisgarh and Venkatgiri Wall Hangings and much more shall be on display and for sale. The exhibition is sponsored by the Office of Development Commissioner (Handicrafts), Ministry of Textiles, Govt. of India. The exhibition cum sale will be open to the public till February 28. When: On till February 28Where: Central Cottage Industries Emporium, Jawahar Vyapar Bhawan, Janpathlast_img read more

Lukewarm response to Bharat Bandh in West Bengal

first_imgKolkata: The nationwide shutdown called by the Congress and Left parties against the fuel price hike on Monday evoked lukewarm response in West Bengal, with vehicular traffic remaining near normal. The ruling Trinamool Congress (TMC) had previously opposed the strike and said the state government would take every possible step to ensure that the public life remains unaffected. In Kolkata, most of the shops and markets remained open while the city’s metro service functioned normally. Also Read – Rain batters Kolkata, cripples normal life However, the number of commuters were significantly less in the early hours on Monday compared to other working days. A large number of public and private buses were seen plying in the city’s important points including Shyambazar five point, Esplanade crossing, Jadavpur and Ruby crossing. The train service in Sealdah and Howrah section under the Eastern Railway was temporarily disrupted as the strike supporters blocked rail movements in Jadavpur and Sreerampur stations. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killed However, they were removed by the police within half an hour. No untoward incidents of violence or clashes were reported. Protesting against the steep hike in fuel price under the BJP-led NDA government at the Centre, the Congress called for the shutdown on Monday. The Left parties including CPI-M, CPI, RSP has also called for a 12-hour long ‘hartal’ (strike) on Monday against the Narendra Modi government’s policies.last_img read more

Will hold rallies in Delhi to oust antipeople Modi govt Abhishek

first_imgKolkata: Trinamool Congress will organise rallies in Delhi to oust the anti-people Modi government at the Centre, said Trinamool Youth Congress president and party MP Abhishek Banerjee.He was addressing a gathering to protest against the hike in the price of petroleum products at Dorina Crossing on Monday afternoon.Banerjee said the prices of petrol and diesel have gone up even on Monday and the Centre has made no attempts till date to reduce the prices of petroleum products. Also Read – Rain batters Kolkata, cripples normal lifeHe said BJP had asked the state government to reduce state excise and VAT. Between 2014-18, Central excise has been increased nine times, while there has been “zero” rise in state excise and VAT.Banerjee alleged that to divert the attention of people, BJP has brought up the Hindu- Muslim issue. “This trick will not work any more. Whenever there is any major problem in the country, BJP immediately brings in Hindu-Muslim and communal issues to divert the attention of people.” Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killedHe said Trinamool is the first political party to raise its voice against the Centre. Immediately after the prices of petroleum products started soaring, party supremo Mamata Banerjee had criticised it. Trinamool Youth Congress started a dharna and held rallies in South and North Kolkata over the issue.”We will continue to protest against the anti-people government till it is ousted,” he said.State Urban Development and Municipal Affairs minister Firhad Hakim said BJP national president Amit Shah has said that the party will remain in power for 50 years, but in reality if it stays for more than five days, people’s ordeal will go up.”Forget about BJP remaining in power at Delhi for 50 years. If they stay for five more days it will be bad for the country. It is a party whose only business is to loot people,” said Hakim.Meanwhile, Trinamool Congress leaders and workers took part in a rally to protest against the prices of petroleum products on Monday. The rally started from Moulali and ended at Dorina Crossing, where a meeting was organised.last_img read more

Kite string slashes throat of SSKM doctor on Maa Flyover

first_imgKolkata: A scooter rider got his throat slit by kite thread (manja) on Maa flyover on Sunday afternoon. He was rushed to SSKM hospital by the police where doctors treated and discharged the injured.On Sunday around 3:20 pm, a doctor at SSKM hospital identified as Dr Saikat Chakraborty was riding his scooter on Maa Flyover to go home in Nayabad. But near Park Circus 4 number bridge his neck and face got entangled in the kite thread. Immediately he stopped his scooter and tried to remove the thread. Meanwhile, a few drivers, who noticed the incident, informed police. Also Read – Rain batters Kolkata, cripples normal lifeUpon receiving the information police personnel went on Maa Flyover and rushed Chakraborty to SSKM hospital. Since last few months several such incidents occurred on Maa Flyover. During October Suresh Majumdar a resident of Bally in Howrah was injured due to kite thread. On October 21, he was riding his motorcycle on Maa flyover, near Topsia and felt something was wrong around his throat. He stopped the motorcycle and saw blood dripping from his throat. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killedWhen he tried to understand what happened and put his hand on his throat, the victim found kite thread. Though police have asked the locals staying adjacent to Maa flyover not to fly kites near the area, no one bothers to obey the order. As a result similar accidents have taken place in the past. In last September, an Information Technology (IT) employee’s throat got slit in the same manner when he was riding his motorcycle on Maa flyover. On December, 2017, a-10-year-old girl’s throat got slit by kite thread and suffered major injuries. Though police say steps would be taken to curb such incidents but no one knows how this practice could be stopped completely.last_img read more

Sobhandeb Chattopadhyay Moloy Ghatak hold prep review meeting ahead of Gangasagar Mela

first_imgKolkata: State Power minister Sobhandeb Chattopadhyay and Public Health Engineering minister Moloy Ghatak held a high level meeting with the senior officials of various departments at the Vidyut Unnayan Bhavan on Wednesday, regarding the preparation of Gangasagar Mela.The state Power department has been making all necessary arrangements in order to ensure uninterrupted power supply during the Gangasagar Mela. According to a Press statement issued by the state Power department, modernisation work has been undertaken to increase the capacity of the 33/11 KV substation at Rudranagar area. Also Read – Rain batters Kolkata, cripples normal lifeIn order to ensure that the pilgrims do not face any inconvenience, the Power department has decided to ensure power supply to 54 points. In the previous year, the department had supplied power to 40 points in the Mela and its adjoining areas. Laying of underground cables is being conducted between Kachuberia and Rudranagar areas. If there is any problem in any area, the power supply would be done by automation through DG system. There will be adequate power arrangement at Bangabasi ground adjacent to Mohunbagan ground, so that the pilgrims do not face any inconvenience during their short stay in the area. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killedThe Power department officials have been instructed to make adequate arrangements to ensure that there is no incident of power cut in the area. Arrangements would also be made to ensure the security of the EHV substation in Kakdwip, as well as meeting the extra demands of power. The state Power minister also urged all other departments to maintain better coordination during the days of Gangasagar Mela. The officials of various departments will visit the venue to assess the preparations ahead of the grand event.last_img read more

Debunking social taboos

first_imgThe socio-historical constructions of India are often essentialized ones, framed in terms of twofold opposition and stereotypes. One of the manifestations of these stereotypes is evident in the portrayal of women and the culture of taboo associated with them.Around the world, different taboos have different sources which go beyond the individual and the household. A much larger driving force that has helped taboos prevail in India is superstition in the name of religion. Acceptance of different practices though is the nature of Indian culture. Yet, accounts of taboo question whether the project of making a ‘liberal’ nation was always fraught with religious prejudices and traditional disbeliefs. There are various taboos existing in India but one which is glaring and needs some attention is the menstrual taboo.  Also Read – Add new books to your shelfSince ages, women have been subjected to derogatory practices just because they menstruate and for such things to flourish it has to thrive at fundamental levels. Unfortunately, families and cultural groups represent these fundamental levels, where people are socialised in a certain way.  For instance, girls are taught from the very beginning that they should not let people know about it, they still have to hide sanitary napkins from male members of the family among other various reasons. This basic foundation for socialisation forces itself to look beyond the building blocks of identity. While periods can be uncomfortable for certain material reasons, a girl child is more uncomfortable because she becomes conscious of other people knowing about it. As a result, faulty socialisation facilitates blind superstition.  Also Read – Over 2 hours screen time daily will make your kids impulsiveThe experiences of female bodily processes have always been construed and placed within the narrow cultural domain in India. While menstruating, women are prohibited to enter temples, kitchen, not allowed to  have intercourse, touch pickles and the list goes on. This stark reality does not call for romanticising the issue rather it calls for normalisation. However, the kind of taboo and derogation that has been vested on the phenomenon, has led to a necessary romanticisation of menstruation.  On a brighter side, feminists like Rupi Kaur and others have helped raise awareness on this issue. Women have come out of their shells and are upfront about discussing this issue now more than ever. Also, being free about discussing periods has become a medium of seeking liberation from downtrodden cultural norms. It should be kept in mind that the enforcement of menstruation as a taboo in an extreme way makes people think of it as liberating. Had taboo not been associated with this, it would have been normalised just like any other biological process. However, normalisation of the issue remains an ideal dream, it keeps oscillating between extremes. Menstruation as a process is intrinsic to the functioning of female biology and the extent to which it has been ritualised results in the facilitation of patriarchy in our society. Menstruation is just like any other biological phenomenon, a loss of certain bodily fluids, for example, sweating or defecation or urination. So, if patriarchy could work on an issue so intrinsic, then it makes easier for us to understand how ingrained patriarchy is in our society and how women have internalised the fact since ages because women have acknowledged menstruation as a taboo – as something impure and have agreed to the restrictions placed on them while they are on their period. Hence, the sense of dirtiness that is associated is internalised at every step. Menstruation is one of the common taboos associated with women. These kind of taboos form the basis of a lot of other complex feminist issues like body shaming, where people keep talking about how they should be comfortable in their own skin and leave aside obsession of attaining a perfect figure. Both of these cases have made women overtly conscious of themselves. Ideally that should not be the case, one should be able to embrace the fact this is just a process, a routined process that is absolutely essential for a female body to function in a certain way and it’s also central to certain other processes in life like child-bearing. Thus, socialisation makes a big difference. It is probably being changed now but there are millions who are still overtly conscious about the fact that they don’t want people to know about their period. Looking for an ideal situation, where there would be no discrimination, remains a distant dream but women have to learn to get comfortable to what is naturally a part of them.last_img read more