ESA takes steps toward quantum communications A team of European
scientists has proved within an ESA study that the weird quantum
effect called 'entanglement' remains intact over a distance of
144 kilometres. The experiment allows ESA to take a step closer
to exploiting entanglement as a way of communicating with
satellites with total security. Quantum entanglement is one of
the many non-intuitive features of quantum mechanics. If two
photons of light are allowed to properly interact with one
another, they can become entangled. One can even directly create
pairs of entangled photons using a non-linear process called
Spontaneous Parametric Down Conversion (SPDC). Those two
entangled photons can then be separated but as soon as one of
them interacts with a third particle, the other photon of the
pair will change its quantum state instantaneously. This happens
according to the random outcome of the interaction, even though
this photon never did interact with a third particle. Such
behaviour has the potential to