Atoms of the soft, silvery metal indium have been chilled to temperatures so cold that the particles can demonstrate strange quantum behaviour, such as forming new types of matter. Because indium isn’t related to any other element that has achieved such an ultracold state, researchers expect these atoms to display surprising quantum properties.
“As a curious experimentalist, I wanted to try something where you really didn’t know what was going to happen,” says at Duke University in North Carolina.
Ultracold atoms exhibit behaviours that typically only happen at the quantum scale, like forming liquids that flow with no viscosity. Since the 1990s, researchers have used ultracold atoms to explore and create new states of matter, make the world’s best clocks and simulate materials that exhibit odd behaviours driven by quantum effects.
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But these experiments have involved only a small number of elements, mostly from the first two columns of the left side of the periodic table. Indium, as a metal found on the right side, has very different properties – which means it could add completely new and unexpected phenomena to this list.
In the past, researchers shied away from cooling indium because the complexity of its atomic properties made the process technically difficult. Typically, to make atoms ultracold, researchers slow them down by hitting them with lasers and electromagnetic forces.
Nicholson and his colleagues knew that the same method would work with indium, but the details of the process – such as creating a cloud of indium atoms to begin the cooling and choosing the best lasers to manipulate them – required a lot of experimentation and adjustments.
“If you want to work with [atoms like] strontium or rubidium, there are any number of PhD theses where you could read on exactly where to get your lasers and exactly how to build your system,” says Nicholson. “We had no such thing. That made it hard.”
Eventually, the researchers were able to push thousands of indium atoms to just 15 millionths of degree Kelvin, precisely control their quantum state and arrange them into a neat array by using carefully tuned lasers. These are minimal requirements for experimenting with ultracold atoms to see, for instance, whether they will form new phases of matter, says Nicholson.
But what exactly such experiments will uncover is still an open question, says at the University of Warsaw in Poland. His team has been trying to calculate how two ultracold indium atoms will scatter off each other, which is a basic building block of a comprehensive model of ultracold indium matter that they are still developing.
at the University of Massachusetts Boston says that ultracold indium atoms will interact in at least one completely new way. When two of these atoms come close to each other, the force they experience will depend on how they are oriented – similar to if a magnet attracted a piece of metal more when the object was pointed to its right than its left.
“These are things that no one has explored [in experiment],” says D’Incao. Nicholson and his colleagues aim to be the first to do so, sometime within the next year.
arXiv
Article amended on 10 January 2025
We corrected Jose D’Incao’s affiliation
