THE WORLD of quantum physics is, for most people, difficult to grasp at the best of times. The latest research published today from the Cavendish Laboratory at Cambridge is unlikely to change that, invoking a new class of subatomic particle with the extraordinary property of existing in two places at once.
These particle – called dipolaritons – are created by the merging (or ‘marriage’) of electrons and photons – and yet despite their provenance as the product of the two, they are themselves indivisible.
Their mixed heritage, being composed of both light and matter, imparts some extraordinary properties to dipolaritons. The researchers, led by Professor Jeremy Baumberg, investigated quantum tunnelling effects in their paper, published today (5 April 2012) in Science.
Quantum tunnelling is the strange property of moving from one energy state to another, without passing through an intermediate state, which is only possible at the quantum level.
In the laboratory, this effect is exploited in the scanning tunnelling microscope which has made the imaging of individual atoms on the surface of a material an almost routine operation.
Until this research it was thought that quantum tunnelling was a property of the wave nature of particles, but this paper shows that it can be controlled by light. Specifically, light in the form of ‘cavity photons’ which are quantum packets trapped to bounce between mirrors sandwiching the oscillating electrons.
Research scientist Peter Cristofolini explained: “These new particles, made of both light and matter, can disappear through the walls of semiconductor at will.”
A peculiar feature of the dipolariton is that it is stretched out in a way analogous to a bar magnet. As a result, it exerts ‘extremely strong’ forces on other dipolaritons. The strong interaction between the particles is of great interest in semiconductor development and has implications for scientists attempting to create condensates, which have parallels with superconductors and superfluids in the development of next-generation electronics.
Because the tunnelling behaviour effectively allows the particles to be in two places at once, they offer the potential to transfer information across semiconductor boundaries in a practical application of quantum mechanics in real-world devices.