Quantum cryptography done on standard broadband fibre London:
The “uncrackable codes” made by exploiting the branch of physics
called quantum mechanics, have been sent down kilometres of
standard broadband fibre. This “quantum key distribution” has
until now needed a dedicated fibre separate from that used to
carry data. But a new technique reported in Physical Review X
has shown how to unpick normal data streams from the much
fainter, more delicate quantum signal. It may see the current
best encryption used in many businesses and even homes. The
quantum key distribution or QKD idea is based on the sharing of
a key between two parties - a small string of data that can be
used as the basis for encoding much larger amounts. Tiny, faint
pulses of laser light are used in a bid to make single photons -
the fundamental units of light - with a given alignment, or
polarisation. Two different polarisations can act like the 0s
and 1s of normal digital data, forming a means to share a
cryptographic key. What makes it se