Featured Research

from universities, journals, and other organizations

Physicists Measure Individual Electrons In Real Time; Ultracold Experiment Opens Door For Basic Studies In Quantum Computing

Date:
May 27, 2003
Source:
Rice University
Summary:
Physicists at Rice University have completed the first real-time measurement of individual electrons, creating an experimental method that for the first time allows scientists to probe the dynamic interactions between the smallest atomic particles.

HOUSTON (May 21, 2003) -- Physicists at Rice University have completed the first real-time measurement of individual electrons, creating an experimental method that for the first time allows scientists to probe the dynamic interactions between the smallest atomic particles.

The research, which appears in the May 22 issue of the journal Nature, is important for researchers developing quantum computers, a revolutionary type of computer that is orders of magnitude more powerful than any computer ever built.

To date, computers have used the binary bit -- represented by either a one or zero -- as their fundamental unit of information. In a quantum computer, the fundamental unit is a quantum bit, or qubit. Because qubits can have more than two states, calculations that would take a supercomputer years to finish will take a quantum computer mere seconds.

Due to the complexities of quantum dynamics, electrons can serve as qubits. They can exist in "up" and "down" states -- single points that are analogous to the ones and zeroes in classical computers -- or in "superposition" states, which are not single points but patterns of probability that exist in several places at once.

The Rice experiments took place in an ultracold chamber chilled to temperatures below those found in deep space. There, for the first time, scientists were able to observe individual electrons as they moved onto and off of a nanoscopic piece of a semiconductor known as a quantum dot.

"Since no one has measured single electron dynamics before, the door is wide open for new investigations," said lead researcher Alex Rimberg, assistant professor of physics and astronomy and of electrical and computer engineering. "These include studies of the interactions between individual electrons, as well as the quantum phenomena that engineers must understand if they ever want to build a working quantum computer."

Rimberg's group, which includes graduate students Wei Lu and Zhongqing Ji, built its quantum dot using an ultra-thin layer of semiconducting gallium arsenide. Using gold wiring, they created a ring-shaped electrostatic field, isolating a small pool of electrons on a 300-nanometer piece of gallium arsenide inside the ring. An extremely sensitive charge-sensing device called a radio-frequency single-electron transistor (RF-SET) was placed next to the pool. Operating in a fashion akin to an AM radio, the RF-SET registered changes in the amplitude modulation of radio waves reflected by the pool. The modulations changed as electrons entered and left the pool.

"We were able to tune this system so that our pool was equally happy with, say, 79 or 80 electrons," said Rimberg. "By raising the power of the electric field, we raised the barrier around the pool, making it very difficult for electrons to enter or leave the pool. That allowed us to slow down the electron motion enough to measure the coming and going of individual electrons."

Though physicists have used SET technology to measure the movement of single electrons for several years, the response time in previous experiments was about 1,000 times slower. Rimberg likened the difference to a system that could detect commuters moving in and out of Grand Central Station.

"Before, you could say that individual people were coming and going from the station, and you knew the average number of people in the station, but each measurement took several minutes, so you could never say precisely when a particular individual arrived or left," said Rimberg.

Like commuters jockeying for position on a railway platform, electrons also interact with one another in close proximity. Rimberg hopes physicists can use the ultracold RF-SET system to test competing theories that explain how electrons influence each another.

The research was sponsored by the National Science Foundation, the Army Research Office and the Robert A. Welch Foundation.


Story Source:

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


Cite This Page:

Rice University. "Physicists Measure Individual Electrons In Real Time; Ultracold Experiment Opens Door For Basic Studies In Quantum Computing." ScienceDaily. ScienceDaily, 27 May 2003. <www.sciencedaily.com/releases/2003/05/030527085300.htm>.
Rice University. (2003, May 27). Physicists Measure Individual Electrons In Real Time; Ultracold Experiment Opens Door For Basic Studies In Quantum Computing. ScienceDaily. Retrieved August 23, 2014 from www.sciencedaily.com/releases/2003/05/030527085300.htm
Rice University. "Physicists Measure Individual Electrons In Real Time; Ultracold Experiment Opens Door For Basic Studies In Quantum Computing." ScienceDaily. www.sciencedaily.com/releases/2003/05/030527085300.htm (accessed August 23, 2014).

Share This




More Matter & Energy News

Saturday, August 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Is It a Plane? No, It's a Hoverbike

Is It a Plane? No, It's a Hoverbike

Reuters - Business Video Online (Aug. 22, 2014) UK-based Malloy Aeronautics is preparing to test a manned quadcopter capable of out-manouvering a helicopter and presenting a new paradigm for aerial vehicles. A 1/3-sized scale model is already gaining popularity with drone enthusiasts around the world, with the full-sized manned model expected to take flight in the near future. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Coal Gas Boom in China Holds Climate Risks

Coal Gas Boom in China Holds Climate Risks

AP (Aug. 22, 2014) China's energy revolution could do more harm than good for the environment, despite the country's commitment to reducing pollution and curbing its carbon emissions. (Aug. 22) Video provided by AP
Powered by NewsLook.com
Former TSA X-Ray Scanners Easily Tricked To Miss Weapons

Former TSA X-Ray Scanners Easily Tricked To Miss Weapons

Newsy (Aug. 21, 2014) Researchers found the scanners could be duped simply by placing a weapon off to the side of the body or encasing it under a plastic shield. Video provided by Newsy
Powered by NewsLook.com
Flower Power! Dandelions Make Car Tires?

Flower Power! Dandelions Make Car Tires?

Reuters - Business Video Online (Aug. 20, 2014) Forget rolling on rubber, could car drivers soon be traveling on tires made from dandelions? Teams of scientists are racing to breed a type of the yellow flower whose taproot has a milky fluid with tire-grade rubber particles in it. As Joanna Partridge reports, global tire makers are investing millions in research into a new tire source. 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