Scientists at Florida State University's National High Magnetic Field
Laboratory (MagLab) have demonstrated a way to improve the performance
of the powerful but persnickety building blocks of quantum computers,
called quantum bits, or qubits, by reducing
interference from the environment.
Published today in the journal Nature, this interdisciplinary collaboration between physicists and chemists may hasten the development of quantum computers.
Quantum computers are one of the holy grails of modern applied physics.
Compared to today's computers, which rely on transistors to process
"bits" of information in the form of binary 0s or 1s, quantum computers
hold the promise of performing certain computational tasks exponentially
faster. Their power could potentially dwarf that of today's machines,
with huge implications for cryptography, computational chemistry and
other fields.
Such astounding feats are possible only in the "quantum" world of atoms
and sub-atomic particles, where the physical rules governing how things
behave are quite different from those of the "classical" world we live
in. But the quantum phenomena that make quantum computers feasible are
also the very reason they are extremely challenging to build.
That's the paradoxical nut that a team of scientists, including
physicists Dorsa Komijani and Stephen Hill, director of the MagLab's
Electron Magnetic Resonance Facility, has spent years attacking. And
while they have not broken that nut open entirely, they have made an
important crack.
To understand their crack, it helps to first know a few basics about quantum mechanics.
While qubits can take many different forms, the MagLab team worked with
carefully designed tungsten oxide molecules that contained a single
magnetic holmium ion. The magnetic electrons associated with each
holmium ion circulate either clockwise or counterclockwise around the
axis of the molecule. These so-called spin states are analogous to the
"0s" and "1s" of the computer you may be reading this on. But because
we're in the quantum world, there's a bonus: the qubit can be in both
the 0 and 1 states at the same time in what is termed a quantum
superposition -- a kind of heaven for decision-averse wafflers. In this
case, the superposition involves a mix of the two spin states, with a
spectrum of almost infinite possibilities between the fully clockwise
and fully counterclockwise states. This is where the added computational
power comes from.
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