Boffins reverse time -

Boffins claim to have reversed time on ultrashort electromagnetic pulses, which could be a breakthrough for electronics communications.

A time-reversed pulse evolves as if time runs backwards which means that any distortions or scattering that occurred at earlier times are taken away. It is a Wibbly Wobbly Timey Wimey thing which may even have uses that are not connected to light such as quantum systems.

The technology was developed by Dr Yonatan Sivan and Professor Sir John Pendry both of Imperial College London who gained 50 points for Gryffindor when they invented insibility cloaks for young wizards to sneak out of school.

According to Physical Review Letters which we get for the sixth dimensional centrefold, reversal has been successfully demonstrated for pulses of a relatively narrow spectrum. So far methods that enable time-reversal of broadband pulses have required complicated techniques, such as reversing the polarity of the neutron flow which makes it pretty inefficient.

However Pendry and Sivan's method opens the way to the efficient reversal of truly few-cycle pulses with devices that are easy to make.

What you have to do is dynamically tune the wave speed in photonic crystals that contain "zero gaps," which are band gaps with a zero width.

Sivan told  PhysOrg,com that a zero-gap serves as an effective "stuff" to admits all the incident light. Second, the existence of two bands at close proximity allows one to transfer energy between them using relatively slow modulations.

In the future, the researchers hope to extend and improve this method of time-reversed electromagnetic pulses, perhaps to send themselves the lottery results.