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 23, 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 23, 2014).

Share This



More Computers & Math News

Wednesday, April 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

High Court to Hear Dispute of TV Over Internet

High Court to Hear Dispute of TV Over Internet

AP (Apr. 22, 2014) The future of Aereo, an online service that provides over-the-air TV channels, hinges on a battle with broadcasters that goes before the U.S. Supreme Court on Tuesday. (April 22) Video provided by AP
Powered by NewsLook.com
Aereo Takes on Broadcast TV Titans in Supreme Court Today

Aereo Takes on Broadcast TV Titans in Supreme Court Today

TheStreet (Apr. 22, 2014) Aereo heads to the Supreme Court today to fight for its right to stream broadcast TV over the Internet -- against broadcasters who say the start-up infringes upon copyright law. TheStreet Deputy Managing Editor Leon Lazaroff explains the importance of the case in the TV industry and details what the outcome of it could mean for broadcasters and for cloud storage services -- as Aereo allows its subscribers to not just watch live TV shows but also store content to a DVR in the cloud. Video provided by TheStreet
Powered by NewsLook.com
Lytro Introduces 'Illum,' A Professional Light-Field Camera

Lytro Introduces 'Illum,' A Professional Light-Field Camera

Newsy (Apr. 22, 2014) The light-field photography engineers at Lytro unveiled their next innovation: a professional DSLR-like camera called "Illum." Video provided by Newsy
Powered by NewsLook.com
Netflix To Raise Prices For New Subscribers

Netflix To Raise Prices For New Subscribers

Newsy (Apr. 21, 2014) Netflix executives say they don't think a $1 or $2 price hike will hurt the service, and they have their sites set on overtaking HBO. 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