“It is the fulfillment of a great intellectual challenge
that has been with us since 1937.” —MARCEL FRANZ
Elusive type of
fermion reported
Majorana particles could be
useful in quantum computing
Fundamental subatomic particles that
make up matter, such as electrons, have
antimatter companions. But Majorana
fermions, first theorized over 70 years
ago, are a class of particles that are
their own antiparticle. They might have
potential applications for storing data in
future quantum computers.
suggests that a pair of Majorana fermions
formed at opposing ends of the nanowire,
Kouwenhoven says. Otherwise, scientists
wouldn’t have expected to see electric
charge navigate the gap between the thin
wire and the superconductor.
By Rebecca Cheung
The hunt for a long-sought particle that
does not have a distinct antiparticle twin
might be over. Dutch physicists report
making a new device that appears to
create the mysterious entity, called the
Previously, scientists have published
ideas about how to engineer the elusive
Majorana fermions, but no team had
actually constructed such a device.
When the physicists adjusted the direction of the magnetic field or removed the
superconductor, the behavior disappeared. “Every time we take out one of
these special ingredients, the Majorana
disappeared,” Kouwenhoven says.
Majorana fermion.
“It is the fulfillment of a great intellectual challenge that has been with us
since 1937,” says Marcel Franz, a physicist at the University of British Columbia in Vancouver. The work, led by Leo
Kouwenhoven of the Delft University of
Technology in the Netherlands, appears
online April 12 in Science.
Kouwenhoven’s team assembled a
device using an indium antimonide
nanowire about 100 nanometers across.
The scientists put a gold metal electrode
at one end of the wire and a supercon-ducting electrode near the other end,
then applied a magnetic field.
Though promising, the work is not
definitive evidence of Majorana fermions.
Surprisingly, the scientists found that
maximum electric charge moved from
the gold electrode end to the superconductor end at zero voltage. This pattern
“I would not describe this as a discovery yet,” says Patrick Lee, a condensed
matter physicist at MIT. Lee says the
study’s conductance measurements
need to be more precise to prove the
existence of these particles. “There
could be a Majorana hiding behind
there,” he says. “It’s not an open-and-closed case.”
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