Researchers determine spin rate of qubit by measuring microwave field inside superconducting

first_img NIST Develops ‘Dimmer Switch’ for Superconducting Quantum Computing Hybrid DQD/superconducting resonator device. Credit: (c) Nature, doi:10.1038/nature11559 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 Most scientists agree that in order to carry out the kind of logic operations needed for scaled up quantum computing, a means of moving information from more than just a single qubit must be found. To date, such transfers have been made to happen between neighboring electrons on the order of nanometers – quantum computers of the future will require transfers on the millimeter scale. To achieve such a scale, the team at Princeton suggest the concept of a “quantum bus” as a means of providing a pathway for communications between more than one spin based qubit.To use a qubit in logic operations its spin rate is observed to be in either an up “1” or down position “0” state. In order for such information to be useful, a means must be used to control the spin state. In this new research the team used microwave signals. By creating a microwave field around the qubit, the researchers were able to change and read its spin state and by extending the concept to create a superconducting circuit that included more than one qubit, they were able to create a quantum bus that allows for the transfer of information between more than one qubit.Coupling distant qubits has been done before using superconducting qubits – the results have lasted for too short of a time however to be usable in a quantum machine. In this new research, the coherence time, as it’s known, has been greatly increased using the quantum bus they created – long enough to allow for large scale quantum computing. The hope is that the idea can be expanded to include the coupling of many more qubits all separated by the large distances involved in constructing an actual quantum computing device. (Phys.org)—Researchers at Princeton University have demonstrated that coupling spin qubits may be feasible over long distances by measuring the microwave field inside of a superconducting circuit to determine the spin rate of a single electron quantum bit (qubit). Their work, as they explain in their paper published in the journal Nature, may be a first step towards creating a true quantum computer.center_img Journal information: Nature More information: Circuit quantum electrodynamics with a spin qubit, Nature 490, 380–383 (18 October 2012) doi:10.1038/nature11559AbstractElectron spins trapped in quantum dots have been proposed as basic building blocks of a future quantum processor. Although fast, 180-picosecond, two-quantum-bit (two-qubit) operations can be realized using nearest-neighbour exchange coupling4, a scalable, spin-based quantum computing architecture will almost certainly require long-range qubit interactions. Circuit quantum electrodynamics (cQED) allows spatially separated superconducting qubits to interact via a superconducting microwave cavity that acts as a ‘quantum bus’, making possible two-qubit entanglement and the implementation of simple quantum algorithms. Here we combine the cQED architecture with spin qubits by coupling an indium arsenide nanowire double quantum dot to a superconducting cavity. The architecture allows us to achieve a charge–cavity coupling rate of about 30 megahertz, consistent with coupling rates obtained in gallium arsenide quantum dots10. Furthermore, the strong spin–orbit interaction of indium arsenide allows us to drive spin rotations electrically with a local gate electrode, and the charge–cavity interaction provides a measurement of the resulting spin dynamics. Our results demonstrate how the cQED architecture can be used as a sensitive probe of single-spin physics and that a spin–cavity coupling rate of about one megahertz is feasible, presenting the possibility of long-range spin coupling via superconducting microwave cavities.Press release © 2012 Phys.org Citation: Researchers determine spin rate of qubit by measuring microwave field inside superconducting circuit (2012, October 18) retrieved 18 August 2019 from https://phys.org/news/2012-10-qubit-microwave-field-superconducting-circuit.htmllast_img read more

Central Forces start moving towards North Bengal from Jangalmahal

first_imgKolkata: Central Forces deployed at Jangalmahal in Bengal started their movement towards North Bengal on Thursday for the first phase of elections scheduled in Cooch Behar and Alipurduar on April 11, after the state government agreed to release 29 companies of Central Forces presently deployed there.The final deployment plan was settled after the CEO of Bengal Ariz Aftab held a detailed meeting with ADG (Law and Order) Siddh Nath Gupta, ADG (Armed Force) Ranvir Kumar and IG (BSF) Y B Kurania at the CEO’s office on Thursday evening. Also Read – Rs 13,000 crore investment to provide 2 lakh jobs: Mamata”We are trying to deploy Central Forces in all the sensitive booths, while the non-critical booths will be managed by forces of the state,” a senior official of the CEO’s office said. The forces that are expected to reach North Bengal by Friday, will add to the seven companies of BSF already posted in the two North Bengal districts, taking the total count of Central Forces to 37. The official did not rule out the possibility of additional forces and said that talks are on with the Election Commission of India for sanctioning another 30 to 35 companies. “There has been no order yet but we are expecting it by Friday,” the official said. Also Read – Lightning kills 8, injures 16 in stateMeanwhile, the state police will deploy 9,000 state armed force personnel for managing the 3,844 polling stations of the two districts. It has been learnt that the state agreed to release the existing 29 companies of Central Forces from Jangalmahal after the Election Commission assured that the forces will be commissioned for the purpose of election only. There is always the fear that release of forces from Jangalmahal may lead to breakdown of law and order in the area, which was a hotbed for Maoists during the previous government’s (Left Front) rule. Sources in the commission said that out of the 29 companies of Central Forces, 11 companies are being sent to Alipurduar while 18 companies are being sent to Cooch Behar. “The law and order situation is under control and we would like to assure all the voters that there will be adequate forces both in the booths and on the road. We are sure about conducting a peaceful election,” said Additional Chief Electoral Officer Sanjoy Basu. The entire force management will be in the hands of the Police Observer and the Special Central Observer Vivek Dubey, who has already held a series of meetings with the top officials of the state. “As per order from the Election Commission, we have already arranged vehicles for the forces which will carry them to North Bengal. They have already started to move and by Friday morning we will be able to release all the forces,” a senior police officer of Purulia said.last_img read more

FTC Sues Amazon Over Kids Unauthorized InApp Purchases

first_img Register Now » Free Webinar | Sept. 9: The Entrepreneur’s Playbook for Going Global 2 min read Growing a business sometimes requires thinking outside the box.center_img Amazon employees said they had a “house on fire” on their hands. And indeed they do.The Federal Trade Commission filed a complaint in federal court today that claims Amazon allowed millions of dollars in in-app charges made by children without parental consent.The suit alleges Amazon’s in-app system permitted children to rack up unauthorized charges for purchases in apps such as “Ice Age Village,” where players use real money to buy virtual acorns and coins for use in the game.Related: Google to Offer Business Owners 2 TB of Free Storage for a Year“Even Amazon’s own employees recognized the serious problem its process created. We are seeking refunds for affected parents and a court order to ensure that Amazon gets parents’ consent for in-app purchases,” said FTC Chairwoman Edith Ramirez, in a written statement.Amazon employees called the unauthorized billing dilemma a “near house on fire,” according to internal emails the FTC found.When kids download games on mobile devices, it is sometimes unclear which virtual items cost real money and which cost virtual money, the FTC statement says. In March 2012, Amazon required a parental password to spend more than $20 on a virtual item. Further, in 2013, a complaint against Amazon argued that even when a parent was prompted to insert a password, that would lift the veil, allowing kids to make charges without needing another password re-entry for anywhere from 15 minutes to an hour.Related: How You, the Local Business Owner, Can Take on AmazonOne little girl had made $358.42 in charges through these applications without her mother knowing, according to the FTC statement. Charges made inside of an app are nonrefundable.The FTC’s litigation against Amazon follows a similar case that the U.S. regulators brought against Apple earlier this year. Apple settled the complaint for $32.5 million. “You cannot charge consumers for purchases they did not authorize,” Ramirez said when Apple settled.Apparently, Amazon still could.Related: Google Gunning for Amazon With Expansion of Same-Day Delivery July 10, 2014last_img read more