Stanford physicists make new form of matter

The laser-cooled quantum gas opens exciting new

realms of unconventional superconductivity.

By Max McClure
Stanford University News

Within the exotic world of macroscopic quantum

effects, where fluids flow uphill, wires conduct without

electrical resistance and magnets levitate, there is an

even stranger family of “unconventional” phenomena:

strongly interacting fermions, a class of particles that

are often very difficult to understand on the quantum

level. These materials often defy explanation by

current theoretical physics, but hold enormous

promise for the development of futuristic technologies

as room-temperature superconductors, ultrasensitive

microscopes and quantum computation.

Last week the scientific world was appalled when

a Stanford team made the announcement in Physical

Review Letters that they had created the world’s first

dipolar quantum fermionic gas– “an entirely new

form of quantum matter,” as Stanford applied physics

Professor and lead author Benjamin Lev puts it. Lev

affirmed that this development represents a major

step toward understanding the behavior of these

systems of particles. Until now, research efforts had

focused on cooling bosons – fundamentally different

from fermions, and much easier to work with. But

now the Stanford team extended these techniques to

gases made of the most magnetic atom: a fermionic

isotope of dysprosium with magnetic energies 4

times larger than previously cooled gases.

He explained that when the thermal energy of

some substances drops below a certain critical point,

it used to be impossible to consider its component

particles separately since the material becomes

strongly correlated and its quantum effects become

difficult to understand and study. Nevertheless,

making the material out of a gas of atoms allows it

to become visible. These quantum gases, the coldest

objects known to man, are where researchers can

observe zero-viscosity fluids – superfluids – that are

mathematical cousins of superconductors.

Thus far, the result of the Lev lab’s high-tech efforts

is a tiny ball of ultracold quantum dipolar fluid. But the

researchers have reason to believe that the humble

substance will exhibit the seemingly contradictory

characteristics of both crystals and superfluids. This

combination could lead to quantum liquid crystals.

Or it could yield a supersolid – a hypothetical state

of matter that would, in theory at least, be a solid with

superfluid characteristics.

The researchers have already begun developing a

microscope to make use of the dipolar quantum fluid’s

unique characteristics. It is the “cryogenic atom chip

microscope”, a magnetic probe that should measure

magnetic fields with unprecedented sensitivity and

resolution. “This kind of probe may even allow for a

more stable form of quantum computation that uses

exotic quantum matter to process information, known

as a topologically protected quantum computer”,

said Lev. “So this new approach is really incredibly

exciting.”

Available at: http://news.stanford.edu/news/2012/june/lev-new--matter-060512.html. Retrieved on: 5 June 2012. Adapted.