Fast tunable coupler could lead to better quantum computing models

first_img(PhysOrg.com) — One of the subjects of immense interest to scientists (and non-scientists as well) is the development of quantum computers. However, there are many challenges associated with quantum computing. One of the difficulties to achieving practical quantum computing is related to the way the quantum bits (qubits) that make up a quantum computer are connected together. “The easiest way to couple superconducting qubits is via fixed coupling, where the coupling strength does not change,” Bialczak says. “Many experiments done with superconducting qubits so far have been with fixed coupling, but there are lots of problems with fixed coupling architectures because they are difficult to scale up to many qubits.”Bialczak worked with a team at UC Santa Barbara to look for a way around the problems caused by fixed coupling. They developed a novel tunable coupler design that has the potential to be scalable, possibly improving current quantum computer designs. The team’s work can be found in the Physical Review Letters article “Fast Tunable Coupler for Superconducting Qubits.”With fixed coupling, Bialczak explains, it is easy to couple the qubits so that they can exchange information, but keeping the qubits from interacting with each other is difficult and causes errors in single-qubit operations and measurement. On top of that, problems with fixed coupling multiply as you add more qubits. “As you increase the number of qubits,” Bialczak says, “it gets increasingly difficult to isolate an individual qubit from the others. It’s like having a room full of people and wanting to isolate each person from the conversation of the other people. You won’t be able to do so because there are so many people…each personal will hear one or more of the other persons’ [conversations].”In order to overcome these issues, the team at UC Santa Barbara developed a method of fast tunable coupling. “With tunable coupling, you can directly turn off the interaction between qubits,” Bialczak says, “The coupler can also arbitrarily tune the coupling strength on nanosecond timescales allowing for fast qubit interaction times while minimizing errors in single-qubit operations and measurement.” For realistic quantum operations, a practical tunable coupler is needed. Such a coupler would need to be tuned quickly, on the order of nanoseconds. Additionally, large on/off ratios are required, as well as scalability so that many qubits can be coupled. “Previous demonstrations of tunable coupling were able to show one or more of the above in a given device, but were unable to combine all the criteria in one device, making them of limited use in realistic quantum computing experiments,” Bialczak points out. The UCSB team hopes that their new tunable coupler will satisfy all these criteria.In order to create the tunable coupler circuit, two superconducting qubits are coupled using a fixed negative mutual inductance. This mutual inductance is shunted with a current-biased Josephson junction. The junction acts as a tunable positive inductance and can therefore cancel out the fixed coupling due to the mutual inductance.“Our coupler also has the added feature of being modular and being able to couple elements over large spatial distances. We can also couple them to other devices and possibly even to qubits from other architectures,” Bialczak says.Right now, the coupler is being used to develop a new measurement scheme that doesn’t destroy prepared quantum states. “This is commonly called a quantum non-demolition measurement scheme,” Bialczak says.Bialczak has great hopes for the applications of this coupler. “We feel this is a general modular superconducting circuit element that can have many applications, even outside of quantum computation.” Copyright 2010 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: Fast tunable coupler could lead to better quantum computing models (2011, March 2) retrieved 18 August 2019 from https://phys.org/news/2011-03-fast-tunable-coupler-quantum.html More information: R. Bialczak, et. al., “Fast Tunable Coupler for Superconducting Qubits,” Physical Review Letters (2011). Available online: link.aps.org/doi/10.1103/PhysRevLett.106.060501center_img Making quantum computing scalable 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.last_img read more

Quantum communication without entanglement could perform faster than previously thought possible

first_img More information: W. J. Munro, et al. “Quantum communication without the necessity of quantum memories.” Nature Photonics DOI: 10.1038/NPHOTON.2012.243 Illustration of the new quantum communication scheme, where information is directly transmitted from one node to another using a transmitter unit and a receiver unit. The scientists calculated that the new approach could potentially enable communication rates several orders of magnitude faster than other approaches. Credit: W. J. Munro, et al. ©2012 Macmillan Publishers Limited In such a system, the performance is inherently limited by the time it takes to establish entanglement between nodes. This time is at best the classical signaling time between the nodes, but with many schemes it is even longer, and increases as network size increases. Since the qubits that store the quantum information are unstable and quickly decohere, quantum memories are required to store quantum information for milliseconds or longer while they wait for entanglement. The result is a theoretical limitation on speed due to the system’s design and the need for additional components – quantum memories – to enable a functioning network.In a new study published in Nature Photonics, scientists from Japan and the UK have presented an alternative design for a quantum communication network that requires neither entanglement between nodes nor quantum memories. Instead, the scheme transmits quantum information in encoded form directly across the network, using devices that act as quantum repeaters (without entanglement) to transmit and receive information between each other. Because this approach doesn’t use entanglement, the communications rate is not limited by the conventional restraints that limit the rates of entanglement-based approaches.”The significance of this work is that we have removed the need for classical messages to herald the generation of entanglement between adjacent nodes,” coauthor Bill Munro of NTT Basic Research Laboratories in Kanagawa, Japan, and the National Institute of Informatics in Tokyo, Japan, told Phys.org. “This classical signal means our qubits at the remote nodes had to wait until it could be found out whether they were entangled or not. With repeater nodes separated by tens of kilometers, this waiting time was on the order of hundreds of microseconds. This means we needed long-lived quantum memories (milliseconds or longer life times) to store the information (entanglement) that was in those qubits. Copyright 2012 Phys.org 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: Quantum communication without entanglement could perform faster than previously thought possible (2012, October 29) retrieved 18 August 2019 from https://phys.org/news/2012-10-quantum-entanglement-faster-previously-thought.html In order to build a quantum internet – a network that is faster and more secure than the current internet – the key is the ability to transmit quantum information between remote quantum computers (i.e., nodes). The most familiar approach involves entangling the links between nodes and then using quantum repeaters at intermediate locations to provide entanglement swapping, extending the range of entanglement across km-long networks. Explore further Quantum networks advance with entanglement of photons, solid-state qubits 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. “Our new scheme removes the need for long-lived quantum memories, as we do not aim to establish entanglement between the remote nodes. Instead we send an encoded signal between the nodes. Once the message has left one node to be transmitted to the next node, the resources available in the first node are freed up and the next message can be sent down the channel (even before the second node has received the first message), thus increasing the rate at which information can be transmitted. Entanglement-based approaches cannot do this, so their only route to higher communication rates is by paralleling resources within the node.”In the new approach, information is stored in matter qubits, such as electron spins, in the transmitter and receiver units. The transmitter, which contains a single-photon source, transfers the information from the matter qubits to the photonic qubits. Then it sends the photonic qubits down an optical fiber to the receiver, which contains a single-photon detector. The receiver operates in reverse, transferring the information from the photonic qubits back to matter qubits. Unlike traditional schemes, the new scheme doesn’t require entanglement between the matter qubits at the two remote nodes. As soon as the transmitter moves the information from the matter qubit to the photonic qubit, the matter qubit is no longer needed, so quantum memory is not required to store its information. After the completion of one cycle, the final matter qubit is checked for errors using a redundant quantum parity code. Since channel losses and source/detector inefficiencies are inevitable, quantum states can easily be degraded during quantum communication. The error correction code protects against this degradation by measuring the states of several matter qubits that all carry the same information. The physicists showed that this encoding process can tolerate photon loss in excess of 50% in the quantum channel between nodes, which allows for nodes to be spaced further apart than usually thought.After the error correction code verifies successful transmission of a qubit, the receiver then acts as a transmitter and sends the information on to the next node in the network. The scientists calculated that the scheme could transmit data at a rate of 107 quantum states per second, and operate over a distance of at least 17 km between nodes. With 48 nodes, quantum information could be transmitted over 800 km with a success probability of greater than 98%. The scientists calculated that the new approach could potentially enable communication rates several orders of magnitude faster than other approaches. In addition to speed, the new scheme also has other routing advantages.”Our solution also makes it very easy to see how one can send information on a more complicated quantum network,” Munro said. “Each node would have a telephone-like number and then we can think of telephone-like exchanges that route the information to where it needs to go. The node that sends the original message does not need to know the route to the final destination. Instead it just needs to get to a local exchange which can route it through the chain using country, region, and city parts of the telephone-like number.”In the future, the researchers plan to tackle some of the technical challenges facing the new quantum communication scheme.”Our future plans are an experimental implementation of this approach,” Munro said. “Currently we are working on ways to improve our local gates within our physical system – a necessary step to showing our new communication scheme.”The key requirement in this new approach is the need for efficient quantum gates within the repeater node,” he added. “In the normal entanglement-based approach, we can work with gates that fail a lot of the time in a heralded way. Currently, efficient quantum gates are experimentally challenging to achieve but they need to be achieved if distributed quantum computers are going to be achieved.” Journal information: Nature Photonicslast_img read more

South India is near Qutab Minar

first_imgThere is much more to south India than the regular idli, dosa and sambhar. The art and craft from the region, for instance, is unknown to many in the northern parts of India. Isha Utsav, a cultural festival, might just bridge that gap. The fair gives Delhi a glimpse of south Indian art, crafts and textiles. ‘The 12 day long exhibition features specially designed crafts from rural India, organic food, daily meditation sessions and live music’ said Anubhav Nath, owner, 1AQ, where the exhibition is being held. Also Read – ‘Playing Jojo was emotionally exhausting’The art, craft and textiles displayed are made from locally sourced natural materials. The product range includes eco-friendly decorative baskets, all-purpose trays, lamps, fragrances, mats, fashionable cotton and jute handbags. Rudrakash, ethnic garments and Yoga wear and T-shirts are the most popular picks. The products are eco-friendly and are made from natural and bio-degradable materials. Stone sculptures, urlis and metal crafts made out of recycled material are other top picks at this ongoing fete. Also Read – Leslie doing new comedy special with Netflix‘On the first day itself, we had a footfall of 500 people. The price range of articles start from Rs 500 and go upto Rs 15,000,’ added Anubhav.The special feature of the festival is an initiative to revive the traditional south Indian foods which were lost in the last few generations.‘The idea is to promote a wholesome range of snacks, drinks and meals, which are a perfect blend of taste, nutrition and convenience. There would also be food sampling of nutritious and wholesome appams, dosas and freshly prepared herbal teas,’ said Abhinav.Another highlight is the Isha Sound and Meditation workshops wherein participants would be taught meditation for a peaceful state of being through ethereal and serene sounds. The classes will happen daily between 4 pm to 7 pm.Go catch it.DETAILAt: 1AQ, Qutab Minar Main RoundaboutOn Till: 23 January Timings: 11 am to 7 pm dailylast_img read more

Outbound passenger count crosses 4000 at Bagdogra Airport

first_imgKolkata: The outbound passenger load at Bagdogra Airport has crossed the mark of 4,000 on Sunday.With a sharp increase in the passenger load at Bagdogra Airport, the outbound passenger count on Sunday was 4,011.It may be mentioned that recently, the announcement of two additional flights of AirAsia from the airport had come and it had taken the total number of flights to 26. The two additional flights are connecting Bagdogra directly with Delhi and Kolkata. Also Read – Heavy rain hits traffic, flightsAccording to the experts, the passenger load is expected to go up further with the summer vacation approaching, as people will choose to visit Darjeeling and Sikkim with schools and colleges remaining closed. It may be recalled that the Mamata Banerjee government has waived the tax on aviation turbine fuel (ATF) and it has helped increase the number of flight operations from Bagdogra. Moreover, the development of necessary infrastructure for tourism in North Bengal has also ensured a constant flow of tourists in the region. A large section of tourists now prefer flights to reach their destination, as it saves time. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedIt was on February 23 that Bagdogra Airport set a new record of crossing the 2 million passenger count in the last fiscal. Moreover, the Chief Minister herself was the 2 millionth passenger, when she took a flight from Bagdogra Airport to return to Kolkata after her North Bengal tour.Bagdogra Airport had witnessed a record increase of passengers by 53 percent in April-December in 2017, compared to that of the corresponding period in 2016, when around 10.61 lakh passengers had availed flights from the airport from April to December. In 2017, the figure went up to 16.28 lakh, which is an increase of over 50 percent. With the increase in passenger count, better passenger amenities have also been ensured at the airport.last_img read more

Picture perfect

first_img17th Bharat Rang Mahotsav organised another phase of Living Legend Series with Raghu Rai. He gave a lecture demonstration on the art of photography in Bahumukh Auditorium, NSD Campus on February 13.He believes that India is a great country for any person to nurture his creativity because the culture is diverse and there are various kinds of people that can be found here. The Padmashree award winner captures real life moments in his camera.  Rai spoke about how he evolved as a photographer and shared a few of his photographs with the audience on various real life situations. Also Read – ‘Playing Jojo was emotionally exhausting’The way he explains the inner depth meaning of each photograph is commendable. Rai truly justified the statement- A Picture is worth a thousand words. He said, “Creativity is not about beauty. It means to capture expression and energy.”Playwright Krishna Sobti also gave a lecture-demonstration as a part of the Living Legend series on February 14. She said, “Love, fear, spirituality and mentality become a part of your thinking when you’re on stage.”last_img read more

Latest death of BJP worker in Purulia a suicide case Police

first_imgKolkata: The man found hanging from an electricity tower in Purulia had committed suicide as per the post-mortem examination, police said on Sunday as life was hit in the area due to the 12-hour strike called by the BJP to protest against the alleged murder of its party workers. Soon after taking charge on Sunday morning, the new Superintendent of Police of Purulia district, Akash Magharia, said: “There was a death of a person at Dava village in Balarampur on Saturday. He was found mysteriously hanging from a tower of high tension wire. We had initiated an unnatural death case and the body was sent for an autopsy that was carried out by a board of five doctors. We have received the report. The board of doctors has clearly stated in the report that the death was due to asphyxia due to hanging and suicidal in nature.” Also Read – Heavy rain hits traffic, flightsWith the police getting the opinion of the board of doctors, they have become sure that Dulal had committed suicide and there was no foul play behind it as claimed by BJP.Partha Chatterjee, secretary general of the Trinamool Congress, said: “The autopsy report showed that it was a suicide. It shows that such controversy over it was created just to malign the state government.”It may be mentioned that Dulal had left home on Friday evening and went missing since then. His motorbike was found on Friday night itself. But his body was found hanging on Saturday morning. Locals had agitated and the police had to chase them away by raising their lathis to ensure that the law and order situation remained in order. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedThe BJP had called a strike in Balarampur on Sunday. But people went out for their work as usual without caring much. There were allegations of threats to the local residents asking them not to come out of their houses and to keep shops shut. Starting from women to middle-aged men, all went out of their houses without paying any heed to the warnings. There were sufficient state-run buses and it helped to ensure a normal day in Balarampur. However, there was police patrolling in sensitive places to avoid any untoward incident that might occur once again leading to deterioration of the law and order situation.The police are also maintaining a strict vigil in the district so that no attempts to disturb peace can be achieved.last_img read more

Pak court dismisses bail plea of Sarabjits killer

first_imgThe accused Amer Sarfaraz alias Tamba had filed the application before Additional District and Sessions Judge Lahore Nasir Rana seeking bail in the case.The judge on Saturday dismissed his plea observing the incident had taken place in “broad daylight” in the presence of other prisoners and the jail authorities besides the prosecution had also produced sufficient incriminating evidence against Tamba.Tamba in his application said he had been implicated in the case as he was not present at the barrack of Sarabjit when he came under attack. Also Read – Pro-Govt supporters rally as Hong Kong’s divisions deepenThe murder weapon had also not been recovered from him either, he claimed.The prosecution informed the judge that both claims of the accused were false as he was caught red-handed while the murder weapon had also been recovered and presented in court. The case had been transferred to Judge Rana over two months ago. Earlier, Justice Shahzeb Saeed and Justice Syed Anjum Raza heard the case.The hearing was held at the Kot Lakhpat Jail in Lahore.Both the accused who are also death row prisoners had allegedly attacked Sarabjit with sharp-edged weapons when he was being moved from one cell to another in the Kot Lakhpat Jail on April, 29, 2013. Also Read – Pak Army ‘fully prepared’ to face any challenge: Army spokesmanSarabjit, 49, later succumbed to his injuries at the Jinnah Hospital in Lahore on May 2. The murder trial began in January, 2014, and subsequently the two alleged killers – Tamba and Muddassar Bashir – were indicted. Both accused denied the murder charges when they were charge-sheeted.However, earlier they had confessed to the murder of the Indian death row prisoner before a one-member judicial commission constituted to probe the murder.They said, “We wanted to take revenge from him (Sarabjit) for killing Pakistanis in bomb blasts in Lahore and Faisalabad”. The commission’s report has also been submitted to the trial court.The Human Rights Commission of Pakistan had labelled Sarabjit’s murder as a “planned one”.Sarabjit was sentenced to death on spying charges and for killing at least 14 Pakistani citizens in bomb blasts in Punjab province in 1990. His family however said that he was a victim of mistaken identity and had inadvertently strayed across the border.last_img read more

Ranveer Singh honoured to do Bajirao Mastani

first_imgActor Ranveer Singh says it is an honour to star in Sanjay Leela Bhansali’s Bajirao Mastani, a love story of Maratha Empire’s Peshwa Baji Rao-I and his second wife Mastani. The film will see actress Deepika Padukone in the role of Mastani, while Ranveer’s Dil Dhadakne Do co-star Priyanka Chopra will play Kashibai, Baji Rao’s first wife.The 30-year-old actor on Tuesday took to Twitter to express his feelings about portraying the Peshwa, whose 315th birth anniversary falls on Tuesday. Also Read – A fresh blend of fame“It’s Peshwa Bajiraos 315th birth anniversary today. Such an honour to be a part of the telling of His love-story ….#HappyBirthdayBajirao,” Ranveer posted.He also shared a still from the film, which saw him in his on-screen character, riding a horse with a sword in his hand.Bajirao Mastani will clash with Bollywood superstar Shah Rukh Khan-starrer Dilwale on the box-office this December 18.last_img read more

Mamata to lay foundation stone for IT Park project on Aug 13

first_imgKolkata: Chief Minister Mamata Banerjee on August 13 will lay the foundation stone for an IT park in Rajarhat which the West Bengal government plans to build in the lines of Silicon Valley in the US. The project, called Silicon Valley Asia, will be set up on 100 acres and aim at creating infrastructure for the technology companies. “The foundation stone will be laid by Chief Minister Mamata Banerjee on August 13,” state IT secretary Debashish Sen said today. Also Read – Rain batters Kolkata, cripples normal life He declined to spell out the finer details of the project which will be announced on August 13. Sen, however, said that the state government has been encouraging the emerging rechnology companies to work from Bengal in the areas like blockchain, artificial intelligence and robotics. Sen, who was speaking at the ‘Digital Sucess Summit’ organised by Indus Net Technolgies, said the state government has been advocating for technologies that will remove language barrier. “Langauge barrier is one of the key reason for a section for not adopting technology. Government is keen for a ecosystem that enables overcoming the language barrier between users and potential users,” he said.last_img read more

A themed bonanza of books for kids

first_imgPuffin Books has tied up with select stores across the country for this promotion titled ‘Booked for the Summer’.The four-week-long program will be running from tomorrow till June 30. Each week will feature a themed collection of books from all over the world, in the order — Adventure and Fantasy, Mythology and Folktales, Learning New Things and Back to School, publishing house Penguin said.“We hope to take kids to different magical lands and have exciting adventures this summer through this fabulous selection of fun books,” a statement said. Also Read – ‘Playing Jojo was emotionally exhausting’To ensure books are easily found, special display racks will be installed across the stores, which will be restocked every week as per the theme.To engage children, storytelling sessions at some of the stores and activity sheets will be given to them. The program will be extensively promoted at all Penguin Random House channels and other relevant channels, like mommy-blogger pages on social media.The stores will be communicating the promotions too via their own social media channels as well as emails, the statement said.Some of the participating stores are Full Circle and Bahri Kids in Delhi, Starmark in Kolkata and Chennai, Story in Kolkata, Sapna Bookstore in Bengaluru, Crossword Bookstore in Nagpur and Baroda and Odyssey in Coimbatore and Chennai.last_img read more