Featured Research

from universities, journals, and other organizations

Physicists Find Way To Control Individual Bits In Quantum Computers

Date:
July 7, 2009
Source:
National Institute of Standards and Technology (NIST)
Summary:
Physicists have overcome a hurdle in quantum computer development, having devised a viable way to manipulate a single "bit" in a quantum processor without disturbing the information stored in its neighbors. The approach, which makes novel use of polarized light to create "effective" magnetic fields, could bring the long-sought computers a step closer to reality.

Optical lattices use lasers to separate rubidium atoms (red) for use as information "bits" in neutral-atom quantum processors -- prototype devices which designers are trying to develop into full-fledged quantum computers. NIST scientists have managed to isolate and control pairs of the rubidium atoms with polarized light, an advance that may bring quantum computing a step closer to reality.
Credit: NIST

Physicists at the National Institute of Standards and Technology (NIST) have overcome a hurdle in quantum computer development, having devised a viable way to manipulate a single "bit" in a quantum processor without disturbing the information stored in its neighbors. The approach, which makes novel use of polarized light to create "effective" magnetic fields, could bring the long-sought computers a step closer to reality.

A great challenge in creating a working quantum computer is maintaining control over the carriers of information, the "switches" in a quantum processor while isolating them from the environment. These quantum bits, or "qubits," have the uncanny ability to exist in both "on" and "off" positions simultaneously, giving quantum computers the power to solve problems conventional computers find intractable – such as breaking complex cryptographic codes.

One approach to quantum computer development aims to use a single isolated rubidium atom as a qubit. Each such rubidium atom can take on any of eight different energy states, so the design goal is to choose two of these energy states to represent the on and off positions. Ideally, these two states should be completely insensitive to stray magnetic fields that can destroy the qubit's ability to be simultaneously on and off, ruining calculations. However, choosing such "field-insensitive" states also makes the qubits less sensitive to those magnetic fields used intentionally to select and manipulate them. "It's a bit of a catch-22," says NIST's Nathan Lundblad. "The more sensitive to individual control you make the qubits, the more difficult it becomes to make them work properly."

To solve the problem of using magnetic fields to control the individual atoms while keeping stray fields at bay, the NIST team used two pairs of energy states within the same atom. Each pair is best suited to a different task: One pair is used as a "memory" qubit for storing information, while the second "working" pair comprises a qubit to be used for computation. While each pair of states is field- insensitive, transitions between the memory and working states are sensitive, and amenable to field control. When a memory qubit needs to perform a computation, a magnetic field can make it change hats. And it can do this without disturbing nearby memory qubits.

The NIST team demonstrated this approach in an array of atoms grouped into pairs, using the technique to address one member of each pair individually. Grouping the atoms into pairs, Lundblad says, allows the team to simplify the problem from selecting one qubit out of many to selecting one out of two – which, as they show in their paper, can be done by creating an effective magnetic field, not with electric current as is ordinarily done, but with a beam of polarized light.

The polarized-light technique, which the NIST team developed, can be extended to select specific qubits out of a large group, making it useful for addressing individual qubits in a quantum processor without affecting those nearby. "If a working quantum computer is ever to be built," Lundblad says, "these problems need to be addressed, and we think we've made a good case for how to do it." But, he adds, the long-term challenge to quantum computing remains: integrating all of the required ingredients into a single apparatus with many qubits.


Story Source:

The above story is based on materials provided by National Institute of Standards and Technology (NIST). Note: Materials may be edited for content and length.


Journal Reference:

  1. N. Lundblad, J.M. Obrecht, I.B. Spielman, and J.V. Porto. Field-sensitive addressing and control of field-insensitive neutral-atom qubits. Nature Physics, July 5, 2009

Cite This Page:

National Institute of Standards and Technology (NIST). "Physicists Find Way To Control Individual Bits In Quantum Computers." ScienceDaily. ScienceDaily, 7 July 2009. <www.sciencedaily.com/releases/2009/07/090707111753.htm>.
National Institute of Standards and Technology (NIST). (2009, July 7). Physicists Find Way To Control Individual Bits In Quantum Computers. ScienceDaily. Retrieved April 17, 2014 from www.sciencedaily.com/releases/2009/07/090707111753.htm
National Institute of Standards and Technology (NIST). "Physicists Find Way To Control Individual Bits In Quantum Computers." ScienceDaily. www.sciencedaily.com/releases/2009/07/090707111753.htm (accessed April 17, 2014).

Share This



More Computers & Math News

Thursday, April 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

German Researchers Crack Samsung's Fingerprint Scanner

German Researchers Crack Samsung's Fingerprint Scanner

Newsy (Apr. 16, 2014) German researchers have used a fake fingerprint made from glue to bypass the fingerprint security system on Samsung's new Galaxy S5 smartphone. Video provided by Newsy
Powered by NewsLook.com
Twitter, Apple Social Data Purchases Likely to Spur More Mergers and Acquisitions

Twitter, Apple Social Data Purchases Likely to Spur More Mergers and Acquisitions

TheStreet (Apr. 16, 2014) The social media data space is likely to see more mergers and acquisitions following Twitter Inc.'s acquisition of tweet analyzer Gnip Inc. on Tuesday and Apples Inc.'s purchase of Topsy Labs Inc. back in December. One firm in particular, the U.K.'s DataSift Inc., could be on the list of potential buyers. Among other social media startups that could be ripe for picking is Banjo, whose mobile app provides aggregated content by topic and location. Banjo could also be a good fit for Twitter. Video provided by TheStreet
Powered by NewsLook.com
Bitcoin Exchange Mt. Gox to Liquidate After Rebuilding Rejected

Bitcoin Exchange Mt. Gox to Liquidate After Rebuilding Rejected

TheStreet (Apr. 16, 2014) Bitcoin exchange Mt. Gox has agreed to liquidate after a Japanese court rejected its plans to rebuild, according to a report by the Wall Street Journal. Mt. Gox filed for bankruptcy protection in February after announcing about 850,000 bitcoins, worth around $454 million at today's rates, may have been stolen by hackers. It has since recovered 200,000 of the missing bitcoins. The court put Mt. Gox's assets under a provisional administrator's control until bankruptcy proceedings begin. Video provided by TheStreet
Powered by NewsLook.com
BlackBerry: The Crash That Launched 1,000 Startups

BlackBerry: The Crash That Launched 1,000 Startups

Reuters - Business Video Online (Apr. 16, 2014) Tech startups in BlackBerry's hometown of Waterloo, Ontario, are tapping talent from the struggling smartphone company and filling the void left in the region by its meltdown. Reuters correspondent Euan Rocha visits the region that could become Canada's Silicon Valley. 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