Featured Research

from universities, journals, and other organizations

Which qubit my dear? New method to distinguish between neighboring quantum bits

Date:
June 18, 2013
Source:
University of New South Wales
Summary:
Researchers have proposed a new way to distinguish between quantum bits that are placed only a few nanometers apart in a silicon chip, taking them a step closer to the construction of a large-scale quantum computer. In a significant feat of atomic engineering, they were also able to read-out the spins of individual electrons on a cluster of phosphorus atoms that had been placed precisely in silicon.

This is Professor Michelle Simmons, director of the Australian Centre of Excellence for Quantum Computation and Communication Technology.
Credit: UNSW

Researchers at the University of New South Wales have proposed a new way to distinguish between quantum bits that are placed only a few nanometres apart in a silicon chip, taking them a step closer to the construction of a large-scale quantum computer.

Quantum bits, or qubits, are the basic building blocks of quantum computers -- ultra-powerful devices that will offer enormous advantages for solving complex problems.

Professor Michelle Simmons, leader of the research team, said a qubit based on the spin of an individual electron bound to a phosphorus atom within a silicon chip is one of the most promising systems for building a practical quantum computer, due to silicon's widespread use in the microelectronics industry.

"However, to be able to couple electron-spins on single atom qubits, the qubits need to be placed with atomic precision, within just a few tens of nanometres of each other," she says.

"This poses a technical problem in how to make them, and an operational problem in how to control them independently when they are so close together."

The UNSW team, in collaboration with theorists at Sandia National Laboratories in New Mexico, has found a solution to both these problems. Their study is published in the journal Nature Communications.

In a significant feat of atomic engineering, they were able to read-out the spins of individual electrons on a cluster of phosphorus atoms that had been placed precisely in silicon. They also propose a new method for distinguishing between neighbouring qubits that are only a few nanometres apart.

"It is a daunting challenge to rotate the spin of each qubit individually," says Holger Bόch, lead author of the new study.

"If each electron spin-qubit is hosted by a single phosphorus atom, every time you try to rotate one qubit, all the neighbouring qubits will rotate at the same time -- and quantum computation will not work. "

"But if each electron is hosted by a different number of phosphorus atoms, then the qubits will respond to different electromagnetic fields -- and each qubit can be distinguished from the others around it," he says.

The UNSW team is part of the Australian Centre of Excellence for Quantum Computation and Communication Technology, a world-leading research centre headquartered in Sydney, Australia.

"This is an elegant and satisfying piece of work," says Professor Simmons, centre director and Mr Bόch's PhD supervisor. "This first demonstration that we can maintain long spin lifetimes of electrons on multi-donor systems is very powerful. It offers a new method for addressing individual qubits, putting us one step closer to realising a practical, large-scale quantum computer."

To make the tiny device, the researchers deposited a layer of hydrogen on a silicon wafer and used a scanning tunnelling microscope to create a pattern on the surface in an ultra-high vacuum.

This was then exposed to phosphine gas and annealed at 350 degrees so phosphorus atoms became incorporated precisely into the silicon. The device was then buried in another layer of silicon.

In a quantum computer information is stored in the spin, or magnetic orientation, of an electron. This spin can not only be in two states -- up and down -- just as in a classical computer.

It can also be in a combination of both states at the same time, allowing exponentially larger amounts of information to be stored and processed in parallel.


Story Source:

The above story is based on materials provided by University of New South Wales. Note: Materials may be edited for content and length.


Journal Reference:

  1. H. Bόch, S. Mahapatra, R. Rahman, A. Morello, M. Y. Simmons. Spin readout and addressability of phosphorus-donor clusters in silicon. Nature Communications, 2013; 4 DOI: 10.1038/ncomms3017

Cite This Page:

University of New South Wales. "Which qubit my dear? New method to distinguish between neighboring quantum bits." ScienceDaily. ScienceDaily, 18 June 2013. <www.sciencedaily.com/releases/2013/06/130618101738.htm>.
University of New South Wales. (2013, June 18). Which qubit my dear? New method to distinguish between neighboring quantum bits. ScienceDaily. Retrieved September 18, 2014 from www.sciencedaily.com/releases/2013/06/130618101738.htm
University of New South Wales. "Which qubit my dear? New method to distinguish between neighboring quantum bits." ScienceDaily. www.sciencedaily.com/releases/2013/06/130618101738.htm (accessed September 18, 2014).

Share This



More Matter & Energy News

Thursday, September 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Stocks Hit All-Time High as Fed Holds Steady

Stocks Hit All-Time High as Fed Holds Steady

AP (Sep. 17, 2014) — The Federal Reserve signaled Wednesday that it plans to keep a key interest rate at a record low because a broad range of U.S. economic measures remain subpar. Stocks hit an all-time high on the news. (Sept. 17) Video provided by AP
Powered by NewsLook.com
Space Race Pits Bezos Vs Musk

Space Race Pits Bezos Vs Musk

Reuters - Business Video Online (Sep. 16, 2014) — Amazon CEO Jeff Bezos' startup will team up with Boeing and Lockheed to develop rocket engines as Elon Musk races to have his rockets certified. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
MIT's Robot Cheetah Unleashed — Can Now Run, Jump Freely

MIT's Robot Cheetah Unleashed — Can Now Run, Jump Freely

Newsy (Sep. 16, 2014) — MIT developed a robot modeled after a cheetah. It can run up to speeds of 10 mph, though researchers estimate it will eventually reach 30 mph. Video provided by Newsy
Powered by NewsLook.com
Manufacturer Prints 3-D Car In Record Time

Manufacturer Prints 3-D Car In Record Time

Newsy (Sep. 15, 2014) — Automobile manufacturer Local Motors created a drivable electric car using a 3-D printer. Printing the body only took 44 hours. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins