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 With

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 440 times larger than previously cooled gases.

He explained that when the thermal energy of some substances drops^A) below^B) a certain critical point, it used to be impossible to consider its component particles separately since the material becomes strongly^C) correlated and its quantum effects become difficult to understand and study. Nevertheless^D), making the material out of a gas of atoms allows^E) 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.

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