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Quantum speed limits are not actually quantum

first_img Both groups—one consisting of Brendan Shanahan and Adolfo del Campo at the University of Massachusetts along with Aurelia Chenu and Norman Margolus at MIT, the other composed of Manaka Okuyama of the Tokyo Institute of Technology and Masayuki Ohzeki at Tohoku University—have published papers on classical speed limits in Physical Review Letters.Over the past several decades, physicists have been investigating quantum speed limits, which determine the minimum time for a given process to occur in terms of the energy fluctuations of the process. A quantum speed limit can then be thought as a time-energy uncertainty relation. Although this concept is similar to Heisenberg’s uncertainty principle, which relates position and momentum uncertainties, time is treated differently in quantum mechanics (as a parameter rather than an observable). Still, the similarities between the two relations, along with the fact that Heisenberg’s uncertainty principle is a strictly quantum phenomenon, have long suggested that quantum speed limits are likewise strictly quantum and have no classical counterpart. The only known limitation on the speed of classical systems is that objects may not travel faster than the speed of light due to special relativity, but this is unrelated to the energy-time relation in quantum speed limits.The new papers show that speed limits based on a trade-off between energy and time do exist for classical systems, and in fact, that there are infinitely many of these classical speed limits. The results demonstrate that quantum speed limits are not based on any underlying quantum phenomena, but instead are a universal property of the description of any physical process, whether quantum or classical.”It is really the notion of information and distinguishability that unifies speed limits in both the classical and quantum domains,” del Campo told Phys.org.As quantum speed limits have potential applications for understanding the ultimate limits of quantum computing, the new results may help to determine which scenarios may benefit from a quantum speedup compared to classical methods. “Quantum speed limits have many applications, ranging from metrology to quantum computation,” del Campo said. “It is exciting to imagine the implications of the classical speed limits we have derived.” More information: B. Shanahan, A. Chenu, N. Margolus, and A. del Campo. “Quantum Speed Limits across the Quantum-to-Classical Transition.” Physical Review Letters. DOI: 10.1103/PhysRevLett.120.070401. Also at arXiv:1710.07335 [quant-ph]Manaka Okuyama and Masayuki Ohzeki. “Quantum Speed Limit is Not Quantum.” Physical Review Letters. DOI: 10.1103/PhysRevLett.120.070402. Also at arXiv:1710.03498 [quant-ph] Journal information: Physical Review Letters Quantum mechanics has fundamental speed limits—upper bounds on the rate at which quantum systems can evolve. However, two groups working independently have published papers showing for the first time that quantum speed limits have a classical counterpart: classical speed limits. The results are surprising, as previous research has suggested that quantum speed limits are purely quantum in nature and vanish for classical systems. Quantum speed limit may put brakes on quantum computers © 2018 Phys.orgcenter_img Citation: Quantum speed limits are not actually quantum (2018, March 15) retrieved 18 August 2019 from https://phys.org/news/2018-03-quantum-limits.html Explore further Source: pixabay 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

Housing complex for the homeless

first_imgBALURGHAT: Those who are homeless and have always been moving to and fro in search of shelter, either to avoid the sweltering summer heat or incessant rainfall, finally have something to rejoice about. The TMC-led Balurghat Municipality has undertaken a mega project to build a housing complex for the homeless at Khadimpur Loknath Mandirpara area, within two months.Official sources informed that the project has been jointly taken up by both the Centre and state. A fund amounting to around Rs 1,22,00,000 has already been sanctioned, to finish the entire project work within the stipulated period. Balurghat civic body chairman Rajen Shill said: “We can accommodate 50 homeless persons in the complex. Initially, we have decided that a four-storey building will be established with the fund. Construction of the ground floor has already been completed, while we have targeted to end the project work by the end of July.”last_img read more

first_img This story originally appeared on CNBC Attend this free webinar and learn how you can maximize efficiency while getting the most critical things done right. Free Webinar | Sept 5: Tips and Tools for Making Progress Toward Important Goals South Korea’s LG has unveiled a 23-karat gold smartwatch on Monday as it looks to challenge Apple in the luxury wearable space.The LG Watch Urbane Luxe costs $1,200 and only 500 will be made, each engraved with its own unique serial number.LG is billing the smartwatch as “more jewelry than wearable,” giving it an alligator leather strap and selling it in a “piano-gloss lacquer case” as its looks to target the high-end buyer.The product launch comes as device makers begin to focus on how to make wearables, in particular smartwatches, more fashionable. In March, Apple unveiled the 18 karat gold Apple Watch Edition to draw luxury buyers to its wearable product.”This blending of craftsmanship and technology is a natural evolution of the smartwatch, which is becoming more of a lifestyle accessory than a piece of hardware. We think this is a good direction for wearables and we want to encourage this transformation,” Chris Yie, vice president and head of marketing for LG Mobile Communications Company, said in a press release.Earlier this year, LG unveiled the LG Watch Urbane at the Mobile World Congress in Barcelona, Spain, and apart from the design, the Luxe version is little changed. It still runs Android Wear – Google’s wearable operating system – and has a 1.3 inch touchscreen display.The wearable market is growing at a stunning rate, albeit off a low base. Shipments in the second quarter came in at 18.1 million units, up about 223 percent from 5.6 million units during the same period last year, according to market research firm IDC. The Apple Watch debuted as the second biggest player by market share with Fitbit at the top.LG is competing in what is becoming a crowded space. The South Korean electronics firm is showing off its new device at consumer electronics show IFA in Berlin this week. Other companies such as Motorola and Samsung are also expected to release new smartwatches this week, according to media reports.LG’s Luxe watch will be available initially in the U.S. for pre-order via REEDS Jewelers beginning on Monday. Register Now » August 31, 2015 2 min readlast_img read more