Physicists split the electron

Posted by Emma Woollacott

Cambridge, UK - A team of physicists from the Universities of Cambridge and Birmingham have shown that electrons are not indivisible - in narrow wires they can divide into two new particles called spinons and holons.

The electron is a fundamental building block of nature and is indivisible in isolation. However, this doesn't seem to be the case when electrons are brought together. Instead, the like-charged electrons repel each other and need to modify the way they move to avoid getting too close to each other. In ordinary metals this makes little difference to their behavior. However, if the electrons are put in a very narrow wire the effects are exacerbated as they find it much harder to move past each other.

In 1981, physicist Duncan Haldane conjectured that under these circumstances and at the lowest temperatures the electrons' magnetism and charge would separate into two new types of particle called spinons and holons.

The challenge was to confine electrons tightly in a 'quantum wire' and bring this wire close enough to an ordinary metal so that the electrons in that metal could 'jump' by quantum tunneling into the wire. By observing how the rate of jumping varies with an applied magnetic field, the experiment revealed how the electron, on entering the quantum wire, had to fall apart into spinons and holons.

The conditions comprised a comb of wires above a flat metal cloud of electrons. The Cambridge physicists clearly saw the distinct signatures of the two new particles, as predicted.

Dr Chris Ford from the University of Cambridge's Cavendish Laboratory said: "Quantum wires are widely used to connect up quantum 'dots', which may in the future form the basis of a new type of computer, called a quantum computer. Thus understanding their properties may be important for such quantum technologies, as well as helping to develop more complete theories of superconductivity and conduction in solids in general. This could lead to a new computer revolution."

Professor Andy Schofield from the University of Birmingham's School of Physics and Astronomy said: "Our ability to control the behaviour of a single electron is responsible for the semiconductor revolution which has led to cheaper computers, iPods and more. Whether we will be able to control these new particles as successfully as we have the single electron remains to be seen."

The paper is published in Science.