Physicists get an up-close look at synthetic quantum materials

June 17, 2010 By Steve Bradt
This sketch shows how a quantum gas microscope hones in on individual atoms in the gas.

(PhysOrg.com) -- Physicists at Harvard University have, for the first time, tracked individual atoms in a gas cooled to extreme temperatures as the particles reorganized into a crystal, a process driven by quantum mechanics. The research, described this week in the journal Science, opens new possibilities for particle-by-particle study and engineering of artificial quantum materials.

"Much of modern technology is driven by engineering materials with novel properties, and the bizarre world of quantum mechanics can contribute to this engineering toolbox," says Markus Greiner, an assistant professor of physics at Harvard who led the research team. "For example, quantum materials could be used to turn heat into electricity, or in cables that transport electricity very efficiently in a ."

"The challenge in understanding the behavior of such materials is that although we have many ideas about how they might work, we lack the tools to verify these theories by looking at and manipulating these materials at the most basic ," Greiner adds. "This is the problem we have set out to tackle."

To circumvent the challenges of studying such materials, Greiner and his colleagues created an artificial quantum material, a cold gas of atoms moving in a lattice made of light. This pancake-shaped cloud, known as a Bose-Einstein condensate, allowed them to study the physics of quantum materials at a much larger scale, essentially simulating what happens in a real material.

The physicists watched individual atoms participate in a dramatic collective transition between two different states of matter, similar to the transition that happens when water freezes into ice. But this transition was driven not by temperature, but by the researchers' manipulation of interactions between the atoms.

"We counted the number of atoms at each site of the lattice," says co-author Waseem Bakr, a graduate student in Harvard's Department of Physics. "When the interactions between the atoms are weak, the number of atoms varies significantly in different sites due to uncertainty that is intrinsic to . When we increase the interactions, these fluctuations vanish, and the atoms arrange into an almost perfect crystal."

Such a transition from a superfluid state -- in which particles can move with no resistance -- to an insulating Mott state -- where the atoms can no longer move -- was first observed by Greiner and colleagues in 2001. However, a quantum gas microscope developed last year by Greiner's group now allows observation of individual atoms as they undergo this transition.

"This microscope is a versatile tool which should be able to shed light on many other phenomena related to quantum materials, such as magnetic materials," Greiner says. "It could even be used for computations that require enormous resources on current computers."

While a simulation similar to the current experiment could, in principle, be carried out on a computer, Greiner says such an approach would quickly become infeasible for a system with more than a few dozen .

Explore further: Ultra-cold temperature physics opens way to understanding and applications

Related Stories

Cross-Dressing Rubidium May Reveal Clues for Exotic Computing

February 25, 2009

(PhysOrg.com) -- Neutral atoms--having no net electric charge--usually don't act very dramatically around a magnetic field. But by “dressing them up” with light, researchers at the Joint Quantum Institute, a collaborative ...

Discovery could pave the way for quantum computing

March 18, 2010

(PhysOrg.com) -- Two experimental systems at the forefront of modern physics research -- a single trapped ion and a quantum atomic gas -- have been combined for the first time by researchers at Cambridge.

Recommended for you

Researchers build bacteria's photosynthetic engine

July 29, 2015

Nearly all life on Earth depends on photosynthesis, the conversion of light energy into chemical energy. Oxygen-producing plants and cyanobacteria perfected this process 2.7 billion years ago. But the first photosynthetic ...

Scientists unlock secrets of stars through aluminium

July 29, 2015

Physicists at the University of York have revealed a new understanding of nucleosynthesis in stars, providing insight into the role massive stars play in the evolution of the Milky Way and the origins of the Solar System.

Rogue wave theory to save ships

July 29, 2015

Physicists have found an explanation for rogue waves in the ocean and hope their theory will lead to devices to warn ships and save lives.

New blow for 'supersymmetry' physics theory

July 27, 2015

In a new blow for the futuristic "supersymmetry" theory of the universe's basic anatomy, experts reported fresh evidence Monday of subatomic activity consistent with the mainstream Standard Model of particle physics.

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

jmas
Jun 19, 2010
This comment has been removed by a moderator.
KronosDeret
not rated yet Jun 21, 2010
well in a sence nuclear fusion and fision is transmutation... so

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.