Scientists at the University of Oslo have discovered a completely new way for atoms to bond together — but these researchers won't be replicating the effect in the lab any time soon. The previously unknown bonding mechanism can only happen in the vicinity of white dwarfs where their intense density and spin creates the intense magnetic fields required. Undaunted by the challenge of reproducing ‘magnetized matter' in the lab, however, researchers believe the insight could advance the field of quantum computing.
Prior to this discovery, chemists had identified two classes of strong molecular bonds: ionic (where electrons from one atom hop over to another) and covalent (where electrons are shared between atoms). But thanks to the work of quantum chemist Trygve Helgaker, we now know that there's a third bonding mechanism — what he's calling "perpendicular paramagnetic bonding."
The discovery happened accidentally when Helgaker and his team were using a computer to predict what would happen to hydrogen molecules in an ultra-high magnetic field. Specifically, they wanted to see what would happen when they subjected computer-generated atoms to magnetic fields of about 105 Telsa, which is 10,000 times more powerful than anything that can be replicated on Earth.
Writing in Nature, Zeeya Merali explains the discovery:
The team first examined how the lowest energy state, or ground state, of a two-atom hydrogen molecule was distorted by the magnetic field. The dumb-bell-shaped molecule oriented itself parallel to the direction of the field and the bond became shorter and more stable, says Helgaker. When one of the electrons was boosted to an energy level that would normally break the bond, the molecule simply flipped so that it was perpendicular to the field and stayed together.
"We always teach students that when an electron is excited like this, the molecule falls apart," says Helgaker. "But here we see a new type of bond keeps the atoms hanging together." The team also reports that a similar effect should occur between helium atoms, which normally don't bond at all.
The atoms are held together by the way their electrons dance around the magnetic-field lines, explains Helgaker. "The way electrons move relative to the field, and their kinetic energy, can become as important for chemical bonding as the electrostatic attraction between the electrons and the nuclei," he says. Depending on their geometry, molecules will turn to allow electrons to rotate around the direction of the magnetic field.
And what's equally remarkable is that the universe can provide the conditions required to create this exact effect — namely the area surrounding white dwarfs. These stars are exceptionally dense and arise when a star collapses, but they're not big enough to go supernova or form a neutron star. These stars can shrink to an object the size of the Earth, but still contain about half the mass of our sun. These super-dense objects spin incredibly rapidly, generating huge magnetic fields that can reach over 100,000 Tesla.
This discovery has some serious implications.
First, it means that we still don't understand all the different chemical mechanisms of the cosmos. Clearly, the environmental conditions around stellar objects result in reactions that we're unable to replicate here on Earth (except through theoretical computer modeling). There may very well be others that we have yet to discover.
And second, the phenomenon suggests a new way to carry information in a quantum computer. Back in 2009, physicists created a weakly bound state called a Rydberg molecule which, theoretically speaking, could carry information. And because Rydberg molecules are highly sensitive to magnetic effects, computational scientists could use magnetic fields as a way to control the strength of the binding — to manipulate them to store and erase quantum memory as needed.
The results of Helgaker's study recently appeared in Science.