Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Letting the spin loose


A team of scientists at the Weizmann Institute of Science has recently demonstrated conclusively that, in very specific circumstances, spin can become separated from charge and progress independently down a wire

Two properties of an electron - its spin and its charge - are generally thought to be inseparable, intrinsic characteristics, no more given to sudden changes or going off on their own than say, the fur on a cat or the paint on a bicycle. But a team of scientists at the Weizmann Institute of Science has recently demonstrated conclusively that, in very specific circumstances, spin can become separated from charge and progress independently down a wire. Their findings appeared in a recent issue of Science.

Spin-charge separation was first predicted in the sixties. The idea was based on a theory that electrons with a range of movement limited to one dimension alone would behave differently from those moving in two or three dimensions. This is because when electrons are lined up head to tail, the influence of the repulsive forces between them becomes overridingly significant. But demonstrating the phenomenon had to wait until technology caught up to the theory.

Prof. Amir Yacoby of the Institute’s Condensed Matter Physics Department and research students Dr. Ophir Auslaender and Hadar Steinberg set up an experiment with quantum wires - so thin that electrons must go single file down their length, limiting flow to a single dimension and direction. "Up to a certain point, one can think of these electrons as cars on a narrow, one lane road: there’s no passing, and the slowest car sets the speed for the rest. A block in the road will bring all traffic to a halt. But here the analogy ends. If you increase car density on a road, traffic invariably slows down, while electrons speed along merrily in high-density flow and slow down when the density decreases. It is in these slow-moving, low density electron flows that things become interesting."

The separation the team achieved between spin and charge rests on the fact that the spins of electrons in these low density, single dimension flows generally follow a preferred arrangement: alternating between the two possible directions of electron spin - up and down. In the experiment, single electrons here and there could jump from wire to wire, allowing the scientists to jumble traffic a bit. So when an electron in the middle having, say, a down spin stepped out of the line, the next electron moved up to fill in, creating a situation with two neighboring ups. This non-ideal state of affairs caused one of them to flip its spin to down, which then caused the next electron, also with a down spin, to flip its spin to up, and so on. Thus the spin traveled down the wire independently of the charge, which stayed tied to the electrons.

Alex Smith | EurekAlert!
Further information:

More articles from Physics and Astronomy:

nachricht Scientists discover particles similar to Majorana fermions
25.10.2016 | Chinese Academy of Sciences Headquarters

nachricht Light-driven atomic rotations excite magnetic waves
24.10.2016 | Max-Planck-Institut für Struktur und Dynamik der Materie

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Ice shelf vibrations cause unusual waves in Antarctic atmosphere

25.10.2016 | Earth Sciences

Fluorescent holography: Upending the world of biological imaging

25.10.2016 | Power and Electrical Engineering

Etching Microstructures with Lasers

25.10.2016 | Process Engineering

More VideoLinks >>>