For the first time physicists have achieved quantum
entanglement between two large clouds of gas. This
achievement means we may live in a future that contains
super-fast quantum computers, instant communication over
unlimited distance, and even a sort of teleportation.
Among other things, quantum computers will be able to
function far more efficiently than the human brain, and to be
much, much larger. It's possible that these experiments are
the forerunners of the first genuinely intelligent machines.
Eugene Polzik and his co-workers at the University of Aarhus
in Denmark have entangled particles from clouds of gases
separated by a long distance, by transferring information from
one to another by laser. They managed to entangle about a
million million caesium atoms, while the previous record was
just four atoms. ?This work should pave the way for a new
generation of experiments to teleport states of matter,? says
Ignacio Cirac, a quantum physicist at Austria?s University of
Innsbruck.
Teleportation will not involve the deconstruction and
reconstruction of humans, Star Trek-style. But it will allow
the condtion of one set of quantum particles to reproduce
more or less instantly in a similar collection of distant
particles. In this way a message encoded in photons of light
could be transmitted from one place to another instantly.
Entanglement will also enable scientists to invent high-speed
quantum computing.
Quantum particles such as atoms or photons can exist in
distinct states, like the head or tail of a coin. These two
states are actually defined by the directions of the atoms?
magnetic fields. Such particles can also exist in both states
at once in superposition, which is comparable to a coin
spinning in the air before it lands.
If we toss two coins at once, their outcomes are independent
of each other--if one is heads, the other could be either
heads or tails. But two entangled quantum particles have
interdependent fates: if one is in a ?heads? state, for
instance, the other must be in a ?tails? state. Maintaining this
kind of superposition is very difficult, and for any practical
applications, entanglement has to include thousands, or even
millions, of particles.
Polzik and his team solved this problem by not using full
entanglement, where the state of each particle depends on
the state of every other particle. Instead, they generated
two loosely entangled clouds of caesium gas, one with
slightly more atoms in a ?heads? state and the other with
slightly more of them in a ?tails? state.
The interdependence of these clouds makes them much
easier to maintain and use than just the altered quantum
states of a few atoms. It?s impossible, however, to maintain
full entanglement of this many atoms for longer than a million-
billionth of a second. Polzik?s team can keep their two clouds
in a loose entanglement for half a millisecond, but they hope
to maintain it for longer in the future. If this can be done,
they will have discovered the basis for the quantum
computers of the future.
Opinion: This experiment suggests, like others have in the
recent past, that faster-than-light communication must be
possible. It could very easily explain the radio silence of the
universe. Why communicate at low velocities like light speed,
when instantaneous communication over unlimited distances
is easy?
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