Featured Research

from universities, journals, and other organizations

Existence Of "Less-Than-Whole" Electronic Charges Confirmed At The Weizmann Institute Of Science

Date:
September 27, 1997
Source:
Weizmann Institute
Summary:
Researchers at the Weizmann Institute of Science have provided the first unambiguous evidence that electrons can behave in an intriguing way that seems to defy common sense.

REHOVOT, Israel - September 22, 1997 - Researchers at the Weizmann Institute of Science have provided the first unambiguous evidence that electrons can behave in an intriguing way that seems to defy common sense.

An electron is a tiny particle that carries the smallest negative charge in nature. Yet a daring theory of physics developed 15 years ago argues that under certain conditions, an electric current behaves as if it were made up of fractions of electronic charges.

In an experiment described in the September 11 issue of Nature, Weizmann Institute physicists measured fractional charges one-third that of an electron.

"Mind-boggling as this may seem, this phenomenon is real," says study author Rafael de-Picciotto. "Of course, electrons don't split into fragments in an electric current, but under certain conditions it is indeed possible to measure a charge smaller than that of an electron."

The research team that conducted this experiment included de-Picciotto, Dr. Mikhail Reznikov, Prof. Mordehai Heiblum, Dr. Vladimir Umansky, Gregori Bunin and Dr. Diana Mahalu.

Intuition vs. Reality

Ever since American physicist Robert Millikan first measured the charge of an electron 80 years ago, this value has been widely regarded as a basic unit of electric charge. Scientists have consequently come to view electrons that make up an electric current as a flow of negatively charged, indivisible "balls." A current made up of fractions of an electronic charge, therefore, would seem a counter-intuitive idea, just as it would be absurd to describe a crowd made up of "less-than-whole" people or street traffic made up of "less-than-whole" cars.

However, if electrons are always regarded as "whole," it is extremely difficult to understand and describe their behavior under certain conditions. For example, some particular instances of this behavior, as in a phenomenon known as the fractional quantum Hall effect, observed in a strong magnetic field, remain unexplained.

In 1982, physicist Robert Laughlin of the United States proposed a theory that explained this effect and provided a very simple way of describing highly complex interactions between electrons. However, this explanation came at a "cost": the theory made the bizarre assumption that an electric current can be made up of odd-denominator fractions of electronic charges - one-third, one-fifth, one-seventh, etc. - of an electron.

In the new experiment, Weizmann Institute scientists designed a sophisticated system to measure such fractional electric charges, should they exist.

The system makes it possible to measure so-called "shot noise." In day-to-day environment, this noise results from random variations in the number and velocity of electrons and causes popping sounds in radio receivers and snow effects in television pictures. Under special laboratory conditions, "shot noise" can be analyzed to reveal the make-up of the electric current. This is possible because the noise has "ripples" left by the flow of electrons in a conductor. The size of each "ripple" is proportional to the unit of electric charge: the smaller the ripple, the smaller the charge, and vice versa.

The scientists passed an electric current through a semiconductor immersed in a high magnetic field, under conditions in which the fractional quantum Hall phenomenon is observed. They used sophisticated equipment to eliminate all extraneous sources of noise. The "shot noise" made by the current was then amplified and measured. It turned out to be made of charges one-third that of an electron.

"This is a beautiful manifestation of the strength of the theoretical methods used to predict such a counter-intuitive phenomenon," says Prof. Heiblum.

The scientists' next challenge is to create conditions for the emergence of even smaller charges, one-fifth of an electron, and to measure these charges. This will require even greater refinement of the system because these tiny charges make smaller ripples that are consequently more difficult to measure.

This work was partly supported by the Israel Science Foundation and Austria's Ministry of Science, Research and Art.

The scientists are members of the Weizmann Institute's Condensed Matter Physics Department. They conducted the research at the Institute's Joseph H. and Belle Braun Center for Submicron Research.

The Weizmann Institute of Science is a major center of scientific research and graduate study located in Rehovot, Israel. Its 2,400 scientists, students and support staff are engaged in more than 850 research projects across the spectrum of contemporary science.


Story Source:

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


Cite This Page:

Weizmann Institute. "Existence Of "Less-Than-Whole" Electronic Charges Confirmed At The Weizmann Institute Of Science." ScienceDaily. ScienceDaily, 27 September 1997. <www.sciencedaily.com/releases/1997/09/970927111135.htm>.
Weizmann Institute. (1997, September 27). Existence Of "Less-Than-Whole" Electronic Charges Confirmed At The Weizmann Institute Of Science. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/1997/09/970927111135.htm
Weizmann Institute. "Existence Of "Less-Than-Whole" Electronic Charges Confirmed At The Weizmann Institute Of Science." ScienceDaily. www.sciencedaily.com/releases/1997/09/970927111135.htm (accessed July 25, 2014).

Share This




More Matter & Energy News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
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
Algonquin Power Goes Activist on Its Target Gas Natural

Algonquin Power Goes Activist on Its Target Gas Natural

TheStreet (July 23, 2014) When The Deal's Amanda Levin exclusively reported that Gas Natural had been talking to potential suitors, the Ohio company responded with a flat denial, claiming its board had not talked to anyone about a possible sale. Lo and behold, Canadian utility Algonquin Power and Utilities not only had approached the company, but it did it three times. Its last offer was for $13 per share as Gas Natural's was trading at a 60-day moving average of about $12.50 per share. Now Algonquin, which has a 4.9% stake in Gas Natural, has taken its case to shareholders, calling on them to back its proposals or, possibly, a change in the target's board. Video provided by TheStreet
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

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