Nonlocal and Superluminal Photonic Tunnelling

Recently we have studied photonic tunnelling with microwave signals.First an introduction to photonic tunnelling and the experimentalprocedure will be presented.

It was found:

1. The tunnelling time represents a universal property.
2. The signal velocityy can exceed the velocity of light, i.e. it can become superluminal.
3. The experimental results of partial reflection point to a nonlocal behaviour of tunnelling photons at least over a distance of some hundred wavelengths.
4. However, a superluminal signal velocity does not violate the principle of causality but it shortens the time span between cause and effect.