Featured Research

from universities, journals, and other organizations

Los Alamos Gets Closer To Quantum Computing

Date:
March 19, 1998
Source:
Los Alamos National Laboratory
Summary:
Researchers at the Department of Energy's Los Alamos National Laboratory have answered several key questions required to construct powerful quantum computers fundamentally different from today's computers.

LOS ALAMOS, N.M., March 17, 1998 - Researchers at the Department of Energy's Los Alamos National Laboratory have answered several key questions required to construct powerful quantum computers fundamentally different from today's computers, they announced today at the annual meeting of the American Physical Society.

"Based on these recent experiments and theoretical work, it appears the barriers to constructing a working quantum computer will be technical, rather than fundamental to the laws of physics," said Richard Hughes of Los Alamos' Neutron Science and Technology Group.

Hughes also said that a quantum computer like the one Los Alamos is building, in which single ionized atoms act like a computer memory, could be capable of performing small computations within three years.

A quantum computer would be much faster at certain computations than traditional computers because it uses the quantum properties of particles such as photons or ions to represent the zeroes and ones that traditional computers employ as binary digits, or bits. These ions, trapped by electromagnetic fields, are termed qubits, short for quantum bits.

A quantum computer won't replace desktop personal computers or even supercomputers, but scientists predict that it will be much better than present-day computers at specialized tasks, such as factoring huge numbers or searching for specific bits of information in massive data bases.

"Quantum computing could fundamentally change the way we protect sensitive information," Hughes said.

Public key cryptography, in which sender and receiver share a "key" for breaking a large number into its factors, is now widely used to provide security for government and industrial information. This cryptographic method has been used since the late 1970s to protect secure electronic messages and telephone communications, but its security depends on the length of time it takes to factor the large numbers used as cryptographic keys.

A quantum computer theoretically could factor such a key number in a few seconds, instead of the many years required by traditional computers. In addition, spies using a quantum computer could reach back into the past and crack any secrets that had been encrypted by the public key method. In conjunction with its research on quantum computing, Los Alamos is developing a new encryption technique known as quantum cryptography in anticipation of the day that public key encryption becomes obsolete.

Los Alamos' quantum computer at this early stage consists of a string of up to eight trapped calcium ions, or qubits, and prototype optical switches that allow researchers to direct a pulsed laser beam onto individual ions and switch the beam from ion to ion.

The Los Alamos team uses lasers to cool the calcium ions to a state of rest in a so-called ion trap. A titanium-sapphire laser will be used to apply light pulses to the ions to perform logic gate operations. These logic gates are the elementary operations at the basis of all computer calculations.

Traditional computers combine individual digital bits in operations such as "and" or "or." Quantum computers can perform other operations not possible with traditional computers and perform reversible versions of ordinary operations. Theoretically, this gives quantum computers the capability of simultaneously performing exponentially larger numbers of operations than traditional computers, Hughes said.

Using the laser, the Los Alamos experiment successfully demonstrated optical addressing, an essential step that a quantum computer will have to execute in actually performing a calculation, Hughes said.

"What we've done is show that we can apply a single laser pulse to a single ion in a trap," Hughes said. "We've done this with very low cross-talk to the locations of the neighboring ions, which can be as close as 20 microns away. This is an essential requirement to perform logic gates on the qubits."

For example, to set up a logic gate involving two qubits will require a sequence of five laser pulses.

The team has been working on its prototype quantum computer for more than two years while other Los Alamos researchers have been trying to solve some of the fundamental theoretical questions that are obstacles to an operating quantum computer. At the APS meeting, Hughes discussed their preliminary answers.

"One question that Los Alamos physicists have solved is crucial to development of a quantum computer. Ions will only remain in a coherent quantum state for a short time. Some scientists have said trapped ions would lose their coherence too quickly to be used practically for computing. We have analyzed how many computational operations can be performed, or in other words, how many of these quantum logic gates can you apply to a calculation?" Hughes said.

The answer is that theoretically as many as 100,000 logic operations could be applied to registers that consist of up to 50 qubits.

Another key question is how long it would take a quantum gate to complete a single operation. The answer, Hughes said, is a few microseconds.

"These experimental and theoretical results clear the path to let us start exploring quantum computing," Hughes said. "We don't expect to start practical computing for years, but we think we're on the right track."

Los Alamos National Laboratory is operated by the University of California for the U.S. Department of Energy.


Story Source:

The above story is based on materials provided by Los Alamos National Laboratory. Note: Materials may be edited for content and length.


Cite This Page:

Los Alamos National Laboratory. "Los Alamos Gets Closer To Quantum Computing." ScienceDaily. ScienceDaily, 19 March 1998. <www.sciencedaily.com/releases/1998/03/980319073644.htm>.
Los Alamos National Laboratory. (1998, March 19). Los Alamos Gets Closer To Quantum Computing. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/1998/03/980319073644.htm
Los Alamos National Laboratory. "Los Alamos Gets Closer To Quantum Computing." ScienceDaily. www.sciencedaily.com/releases/1998/03/980319073644.htm (accessed July 25, 2014).

Share This




More Computers & Math News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Bill Gates: Health, Agriculture Key to Africa's Development

Bill Gates: Health, Agriculture Key to Africa's Development

AFP (July 24, 2014) Health and agriculture development are key if African countries are to overcome poverty and grow, US software billionaire Bill Gates said Thursday, as he received an honourary degree in Ethiopia. Duration: 00:36 Video provided by AFP
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Robot Parking Valet Creates Stress-Free Travel

Robot Parking Valet Creates Stress-Free Travel

AP (July 23, 2014) 'Ray' the robotic parking valet at Dusseldorf Airport in Germany lets travelers to avoid the hassle of finding a parking spot before heading to the check-in desk. (July 23) Video provided by AP
Powered by NewsLook.com
Facebook Earnings Put Smile on Investors Faces

Facebook Earnings Put Smile on Investors Faces

Reuters - Business Video Online (July 23, 2014) Facebook earnings beat forecasts- with revenue climbing 61 percent. Bobbi Rebell reports. Video provided by Reuters
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