Two spin chains in an optical lattice. The top chain in paramagnetically ordered, and the bottom chain has a spin-spin interaction that induces antiferromanetism. The background (green) shown an actual image from the quantum gas microscope with tens of thousands of individual atoms in an optical lattice.
Credit: Markus Greiner, Harvard University
BRISBANE: The properties of a magnet have been simulated at a single-atom level, providing the first evidence of a 'quantum magnet' in an optical lattice - opening the door to engineering new and unusual materials.
Physicists at Harvard University in Boston have succeeded in manipulating the quantum properties of ultra-cold atoms trapped in an optical lattice, using a quantum gas microscope to see the atoms flip between two different types of magnetism - paramagnet and antiferromagnet.
A paper describing the new technology, published in today's issue of the British journal Nature, relies on quantum physics; specifically the bizarre and curious fact that the spin - or magnetic orientation - of a particle (in this case a very cold rubidium atom) can point into multiple directions at the same time.
How magnetism arises in single atoms
When these atoms are placed in a sequence, the interaction between the atoms determines their orientation, and hence the magnetic state they are in. Understanding how these magnetic interactions occur is critical for the development of a variety of new technologies such as quantum computing and superconductivity.
If these emerging technologies are ever to become a reality, they'll need materials with bizarre quantum mechanical properties. However, there's an issue.
"The problem is that what makes these materials useful often makes them extremely difficult to design," explained senior author and physicist Markus Greiner.
"They can become entangled, existing in multiple states at the same time. Normal computers have trouble representing this, so we had to take another approach," he added.
Development of a 'quantum simulator'
At temperatures very close to absolute zero (-273 Celsius), the magnetic-ordering of atoms can be studied in quantum gases, which can be used to simulate the behaviour of real world quantum materials. They provide an enlarged and idealised model of a material that can be studied on a single atom level.
Crucially, the novel approach used by the research team imparts magnetic properties into the arrangement of atoms within an optical lattice (a Mott insulator), rather than the atoms' quantum mechanical spins, producing a 'quantum simulator'.
There is now a way of studying and manipulating quantum material in a much more controlled environment.
"It is a nice piece of work demonstrating quantum interactions, and a major step forward concerning measurement techniques and their measurement," said physicist Laszlo Kish from Texas A&M University in the USA, who was not involved in the study.
A crucial first step
By altering the strength of the magnetic field applied to the lattice, the team were able to control in what 'state' the atoms were in, and in so doing, they could change the magnetic properties of individual atoms.
"When the external magnetic field was strong, all of the magnets aligned to it, forming a paramagnet," said co-author and postdoctoral fellow Jonathan Simon.
"When we reduced the magnetic field, the magnets spontaneously anti-aligned to their neighbours, producing an antiferromagnet."
On its own, such reorganisation is not new. However, the reorganisation normally relies on heat - and this was not the case in this study. "The temperature was so low that thermal fluctuations were absent," said Simon. "Our fluctuations arose from quantum mechanics."
"Observing quantum magnetism in a cold gas is a crucial first step towards quantum simulation of real magnetic materials," said Greiner.
"There remain many exciting questions to answer, and we have only just scratched the surface. By studying the bizarre and wonderful ways that quantum mechanics works, we open new perspectives not only for developing novel high tech materials, but also for quantum information processing and computation," he added.
Ball Magnet
Hello Sir/Ma'am
Cosmos magnetic field was the human source of energy without this magnetic energy science technology never exist, no single electronic devices will survive. but a couple of years ago cosmos scientist said its getting so difficult to understand the current cosmos physics. quantum magnet it was the same thing as scientist told before. quantum magnet needs quantum magnetic energy, ball magnet will help how to find quantum magnetic energy. a marble size magnet at trillium axis will lead how's this energy work. putting 80 Pc's of marble size ball magnet will arranges ti self to accelerate it's energy.
ergarm_122364@yahoo.com
hmm..
I think you want "Nexus" magazine...not "Cosmos"