Month: August 2019
Citation: Creating a six-qubit cluster state (2009, November 2) retrieved 18 August 2019 from https://phys.org/news/2009-11-six-qubit-cluster-state.html Quantum computing: Entanglement may not be necessary The idea of entangling more qubits appears to be gaining traction with a recent experiment conducted the University of Rome in Italy. Giuseppe Vallone is a member of group that was able to entangle a two-photon, six-qubit cluster state. “The degree of entanglement increases with more qubits,” Vallone tells PhysOrg.com. “If you want a bigger entanglement, you need to be able to work with more qubits. This is moving us in that direction.” The results of the experiment can be found in Physical Review Letters: “Experimental Entanglement and Nonlocality of a Two-Photon Six-Qubit Cluster State.”Vallone and his peers believe that this represents the first time a six-qubit linear cluster state built using a two-photon triple entangled state has been experimentally demonstrated. The demonstration aims at creating a hybrid method of increasing entanglement by adding more qubits, but also limiting the decoherence that comes when a greater number of particles is involved with the system. “If we can increase the number of particles and degrees of freedom,” Vallone explains, “you can get a more highly entangled state, which would have a number of possible uses in a possible future quantum technology.”In order to set up the experiment, Vallone and his colleagues prepared a six-qubit state that was hyper-entangled using two photons with triple entanglement. Longitudinal momentum and polarization were used to encode three qubits in each particle, and then a series of unitary transformations were performed in order to entangle some of the qubits. The process was an extension of work that has been done to create four-qubit states.To make sure entanglement had taken place, measurements had to be taken. “We measured each particle with the encoded qubits, and measured their states,” Vallone says. “Entanglement is a correlation between different systems, and we were able to compare the measurements on the two photons and see that there was entanglement.”Going forward, Vallone hopes that the number of qubits used can be increased to eight. “When you increase the qubits, the computational power grows exponentially,” Vallone says. “So it is important to see if we can get this effect with a higher number of qubits. Now that we have shown that it can be done with six, the next step is go on to eight, and then add even more qubits.” This way, he continues, it should be possible to eventually use the method for practical quantum computation. “We are trying to use the two-photon state to perform a quantum algorithm that can be seen as a proof-of-principle demonstration of a quantum computer, and I think that we will be able to get there at some point.”More information: Ceccarelli, et. al. “Experimental Entanglement and Nonlocality of a Two-Photon Six-Qubit Cluster State,” Physical Review Letters (2009). Available online: http://link.aps.org/doi/10.1103/PhysRevLett.103.160401. Copyright 2009 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. 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 (PhysOrg.com) — Many scientists believe that quantum entanglement is required in order for effective quantum computing. Entanglement takes place when there is a connection that exists between two objects – even when they are spatially separated – that allows what happens to one to happen to the other. The link is such that each entangled object cannot be adequately described without its counterpart. So far, entangling qubits for practical use has been difficult, since scientists want to be able to entangle several qubits at once.
Liu notes in the paper, that wastewater (the stuff that goes down the toilet when flushed) or sewage, as it’s more commonly known in other countries, is a great source of environmental pollution and at the same time, is a truly important and often overlooked source of energy, which, unfortunately generally is not collected and used. It’s also an expensive by-product of human existence. Every day billions of people contribute to the ever growing problem of what to do with all the human waste that is created.In addition to organic material, wastewater often contains other materials that need to be removed in order to reuse the water for other purposes. In their lab the team tested their fuel cell’s ability to separate clear aromatics (perfumes), azo dyes, pharmaceuticals, personal care products and endocrine-disrupting compounds (birth control pill chemicals that wind up in urine) from wastewater samples and found they were able to separate them completely from the organic material thus producing clean water.To allow the system to use visible and regular sunlight rather than UV, the team modified the electrodes with semiconductors (such as CdS) which means of course the system, if industrialized, could be used outside as an add-on perhaps to existing wastewater treatment plants.So far the team hasn’t listed cost estimates for building an electrical/wastewater treatment facility with their new technology, but it’s not hard to see how useful such a plant would be in areas where sewage is sometimes not treated at all, but simply dumped into rivers or streams, or worse, in the streets. In addition to helping clean up such places, the people in those areas would benefit from the electricity that would be produced in the process. Wastewater: Energy of the future? 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. (PhysOrg.com) — Yanbiao Liu and his colleagues from Shanghai Jiao Tong University, have succeeded in building a device capable of both cleaning wastewater and producing electricity from it. Using light as an energy source the team created a photo-catalytic fuel cell that used a titanium dioxide nanotube-array anode and a cathode based on platinum. The light energy degrades the organic material found in the wastewater and in the process generates electrons which pass through the cathode converting it into electricity. The team has published its results on Water Science & Technology. More information: A TiO2-nanotube-array-based photocatalytic fuel cell using refractory organic compounds as substrates for electricity generation, Chem. Commun., 2011, Advance Article, DOI: 10.1039/C1CC13388HAbstractA TiO2-nanotube-array-based photocatalytic fuel cell system was established for generation of electricity from various refractory organic compounds and simultaneous wastewater treatment. The present system can respond to visible light and produce obviously enhanced cell performance when a narrow band-gap semiconductor (i.e. Cu2O and CdS) was combined with TiO2 nanotubes.via Royal Society of Chemistry Explore further © 2011 PhysOrg.com Citation: Chinese team develop fuel cell that can clean water as it generates electricity (2011, August 19) retrieved 18 August 2019 from https://phys.org/news/2011-08-chinese-team-fuel-cell-electricity.html
More information: Extractable work from ensembles of quantum batteries. Entanglement helps, arXiv:1211.1209 [quant-ph] arxiv.org/abs/1211.1209AbstractMotivated by the recent interest in thermodynamics of micro- and mesoscopic quantum systems we study the maximal amount of work that can be reversibly extracted from a quantum system used to store temporarily energy. Guided by the notion of passivity of a quantum state we show that entangling unitary controls extract in general more work than independent ones. In the limit of large number of copies one can reach the thermodynamical bound given by the variational principle for free energy.via Arxiv Blog (Phys.org)—Theoretical physicists Robert Alicki and Mark Fannes of the University of Gdansk and the University of Leuven respectively, have uploaded a paper to the preprint server arXiv where they theorize that it should be possible to build an almost perfect entangled quantum battery. They suggest that as the number of entangled batteries increases, their overall performance approaches the thermodynamic limit. © 2012 Phys.org Explore further Chinese team builds first quantum router Journal information: arXiv The teams’ ideas are based on work that has shown that some quantum systems possess some amount of energy while others do not, i.e. those in a passive state. The difference between the two is considered to be extractable work. In their paper the two show that under normal circumstances, the work extracted from such a system isn’t perfect, but when entanglement is considered, things can be improved. They suggest that if a quantum battery were made that was also entangled, more work could be extracted from the system as more of the entangled batteries are added to the system. Such work could theoretically be extracted instantly, because of the properties of entanglement, which they say, would mean that as more batteries are added, the closer the whole system would come to being a perfect battery, i.e. one that doesn’t lose any energy when it’s transferred.Their theory is not without its flaws, the pair acknowledge, the main one being that no one knows how to build such a battery using current technology. Another is that even if there were a way, the practicalities of building a real battery would likely introduce inefficiencies into the system, removing its perfection.On the other hand, as some have noted, nature seems to have found a away to overcome the problem of building such a battery as, biologists have shown that the process of photosynthesis achieves perfect energy transfer, though nobody has been able to explain how.If ever an entangled quantum battery were made with nearly perfect energy transfer, it could be used to power atomic or even subatomic devices, or perhaps more practically, allow for the creation of batteries that are far superior to those used in everyday applications such as lithium-ion battery packs. 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: Physicists theorize entangled quantum batteries could be almost perfect (2012, November 9) retrieved 18 August 2019 from https://phys.org/news/2012-11-physicists-theorize-entangled-quantum-batteries.html
Citation: Research trio claim landslides key to mountain longevity (2013, June 27) retrieved 18 August 2019 from https://phys.org/news/2013-06-trio-landslides-key-mountain-longevity.html Scientists have believed for many years that “quiet” mountain ranges—those that are geologically dormant—tend to erode mostly due to rivers that flow around them or down their sides, cutting away at their bedrock. But until now, very little research has been done to find out why some mountain ranges last much longer than others.To find out, the researchers in this latest effort built computer models that simulate the impact that flowing rivers have on mountain ranges. They found that the type of sediments in the river water had a very large impact on erosion—the grittier the water, the larger the impact. That was not really new, other researchers have suspected as much. What was new was that the computer simulations showed that landslides had a far bigger impact than has been previously suspected. Interestingly, the computer models showed that they can cause mountains to erode faster than normal, or slower, depending on the type and location.Typically, landslides cause a large amount of rock and dirt to fall into a river; if that material is gritty then the landslide will likely cause the mountain to erode faster than it would have otherwise. On the other hand, if a landslide causes a backup in the river, then dirt, rocks and silt can build up in a river basin, effectively causing a slowing of river flow and thus erosion. Such slowing, the researchers found, could lead to a smoother landscape resulting in fewer landslides. This scenario would account for the vast differences found in mountain range ages. The Appalachian Mountains in the U.S., the researchers note, are several hundred million years old—older models suggest they shouldn’t have lasted longer than tens of millions of years. The type of landslides they experienced over the years, the researchers assert, helped the Appalachians hold steady. Landslides linked to plate tectonics create the steepest mountain terrain Photo of White Mountain peak taken in the Alpine Zone. Credit: Jonathan Lamb/Wikimedia Commons (Phys.org) —A trio of researchers, two from Aarhus University in Denmark and a third from the University of Melbourne in Australia, claim in a paper published in the journal Nature that mountain longevity is likely due to the type of landslides that occur at their base. They’ve created computer simulations that recreate the conditions that lead to mountain erosion and say landslide types can mean the difference between short- and long-lived mountain ranges. © 2013 Phys.org Journal information: Nature Explore further More information: Nature 498, 475–478 (27 June 2013) doi:10.1038/nature12218 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.
Leading stock exchange BSE on Tuesday revised the permissible daily trading limit for shares of Jet Airways and 19 other companies, as part of a surveillance action.The new limits, which ensure that stock prices do not go up or down beyond a level during a trading session, will be effective from Wednesday. In a circular, BSE said the price of Jet Airways cannot change by more than 10 per cent in a day. The stock price of Jet Airways has spurted by 48 per cent in the last five trading sessions. The company’s shares on Tuesday closed at Rs 376.95 apiece on the BSE, up 8.29 per cent.
Kolkata: Eastern Railway has secured the first position, both in suburban passenger traffic and also for earnings among suburban sections of all the Zones in Indian Railways.It may be mentioned here that in 2017-18, the Eastern Railway has succeeded in carrying 1,031.48 million suburban passengers, indicating a growth of 3.46 percent over last year. It has also earned Rs 628.93 crore during 2017-18 from just suburban passenger traffic, registering a growth of 4.20 percent. Also Read – Heavy rain hits traffic, flightsEastern Railway has carried a total of 1,223.15 million passengers during 2017-18, which is 3.29 percent higher than that of the previous year. An earning of Rs 2,668.06 crore was also registered, which is 3.44 percent higher than the amount earned during 2016-17. Eastern Railway has also strengthened ticket checking, helping it to earn extra revenues.To check ticketless travelling, Eastern Railway has further strengthened ticket checking drives all over its jurisdiction, encompassing all the four Divisions like Howrah, Sealdah, Asansol and Malda. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedDuring the financial year 2017-18, around 24.40 lakh cases were found, in which passengers were fined for travelling without or with improper ticket. The un-booked luggage detected also contributed to the generation of extra revenues. This is also 11 percent higher than that of last year. Around Rs 48 crore was realised from vigorous ticket checking drives, registering a growth of 21 percent over the last financial year.