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PHYSICISTS have found a relatively easy way to make a Bose-Einstein
condensate, the bizarre state of ultra-cold atoms that is helping to shed light
on the quantum world.

When cooled to near absolute zero, atoms of certain elements merge into a
single quantum state to form a Bose-Einstein condensate (BEC), a form of matter
that possesses many of the properties of a quantum wave. Physicists usually have
to make these condensates in complex “traps” comprising ultra-high-vacuum
chambers surrounded by laser beams and large magnetic coils.

But now scientists report that they can make a BEC much more easily—on
the surface of a chip. The advance comes from a team led by Jakob Reichel at the
University of Munich and independently by Claus Zimmermann’s team at the
University of Tübingen.

The researchers used wires deposited on a chip to create magnetic fields.
They then trapped a cloud of atoms in these fields, a fraction of a millimetre
above the surface, and cooled them to form a BEC. The chip does the job 10 times
as fast as a normal trap and does not require nearly such a high vacuum, Reichel
says.

The chips could one day be used to pluck individual atoms from a BEC, says
Jörg Schmiedmayer, a physicist at the University of Heidelberg. Their
quantum states could then be entangled, so that a measurement of the state of
one immediately affects the state of the other. The atoms could then act as
“qubits”—quantum-computing bits that can represent 0, 1 or a mixture of
both at the same time.

Quantum computers are probably decades away, but Schmiedmayer says the new
chips should make possible a wide variety of important experiments on the
quantum world: “You have a magnetic trap that’s much, much simpler than any
other experiment and that is much more versatile.”