Breaking the laws of physics to tame unruly particles

Scientists from Stanford University have created a device which breaks a key physical law, allowing light to be controlled in a similar way to electricity. This revolution is likely to yield a new class of nanoscale technology and will be applied within on-chip communications, accelerators and microscopy.

This magical new device – called a photonic crystal – is made by etching a grid of tiny cavities into silicon. As described within Nature Photonics, applying a precisely tuned varying electric current to this device creates a synthetic magnetic field introducing a virtual charge (and force) on the photons allowing their speed and path to be manipulated. The production of a force or charge on a photon creates resistance against the particle movement in certain directions, and so the photon will try and follow the path of least resistance. This manipulation of the photon path breaks the time-reversal symmetry laws of physics meaning that a photon will have different properties travelling in different directions.

Magnetic fields are commonly used to steer electrons, and this is one of the fundamental principles of electronics. Photons could not previously be controlled in this way due to their neutral charge, and so could run free even in very intense magnetic fields.

Photons can now be used to improve performance within fibre optic cables, as once the photon enters the new device it cannot turn back, therefore eliminating the reflective noise known as backscatter. This will minimise other problems which are found within fibre optics and other light control mechanisms.

http://www.nature.com/nphoton/journal/vaop/ncurrent/pdf/nphoton.2012.236.pdf