From the New Scientist
comes this report of a device that can conceal events and not just
objects. Termed “Time Cloak,” it can
hide secret messages through a trick of light, making information invisible to
all but the intended recipient.
Like an invisibility cloak
that makes something disappear in plain sight, a time cloak could
conceivably make an event disappear in time. It works by manipulating light
traveling along an optical fibre.
The device might still be a
long way before finding applications in hiding, say some crime, as the New
Scientist article conjectured. Joseph Lukens, an electrical engineer at
Purdue University in the USA gives some current applicability:
"With this new device,
we don't just limit ourselves to thinking about cloaks as a way of preventing
somebody from getting information, but also as a way to enable
communication.”
Lukens and his colleagues
created two different communications channels using lasers tuned to two
different frequencies. One is a regular frequency and the other is a
time-cloaked channel that remains hidden unless you know it's there. Photons
from each laser traveled along the same fibre, but only the intended recipient,
who just needs to tune in to the right channel, gets to see the secret
information. According to Lukens, “One guy sees nothing, the other guy sees
everything."
Not
only could the cloak deliver the messages, it also successfully fended off
outside attempts to scramble the information. A similar device could one day
improve current communication systems, says Moti
Fridman at Bar-Ilan University in
Israel.
"As we get closer and
closer to the limits of current data transfer systems, we need to consider
creative ideas for increasing the bandwidth in current systems with minimal
changes," says Fridman. "This is a beautiful example for using
cloaking."
Journal Ref. : Optica, DOI:
10.1364/OPTICA.1.000372
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