Free-range atoms, roaming around without restrictions, have been captured on camera for the first time – enabling physicists to take a closer look at long predicted quantum phenomena.
It's a bit like snapping a shot of a rare bird in your back garden, after a long time of only ever hearing reports of them in the area, and seeing the food in your bird feeder diminish each day. Instead of birdwatching, though, we're talking about quantum physics.
The US researchers behind the breakthrough carefully constructed an "atom-resolved microscopy" camera system that first puts atoms in a contained cloud, where they roam freely. Then, laser light freezes the atoms in position to record them.
"We are able to see single atoms in these interesting clouds of atoms and what they are doing in relation to each other, which is beautiful," says physicist Martin Zwierlein, from the Massachusetts Institute of Technology (MIT).
Being able to capture these atoms as they interact means new opportunities to study matter at the smallest of scales, in the quantum realm – and the researchers have already taken a closer look at several rare atom patterns.
These patterns include a state known as Bose-Einstein condensation – made up of bosons, and fermions as they pair up. It all adds to our understanding of how incredibly tiny atoms behave and change in their behavior.
As another example, the team was able to directly capture an image of a 'de Broglie wave', named after French physicist Louis de Broglie, in which bosons bunch together. This theory is partly responsible for the beginnings of modern-day physics.
While these scenarios have been studied before, now they can be analyzed in more detail, giving scientists the opportunity to take measurements and make observations not previously possible – right down to individual atoms.
"[Existing] techniques allow you to see the overall shape and structure of a cloud of atoms, but not the individual atoms themselves," says Zwierlein. "It's like seeing a cloud in the sky, but not the individual water molecules that make up the cloud."
Trying to track and monitor atoms is incredibly tricky. These particles are just a tenth of a nanometer in size – that's about a millionth of the width of a human hair – which is why these complex imaging setups are required.
Now that the researchers behind the new approach have shown it can work, they want to use it to investigate other types of atom interactions and behaviors. Of particular interest are the rarest and least studied scenarios, with quantum Hall physics – where electrons have unusual interactions with magnetic fields – on the shortlist.
"When you see pictures like these, it's showing in a photograph, an object that was discovered in the mathematical world," says MIT physicist Richard Fletcher.
"So it's a very nice reminder that physics is about physical things. It's real."
The research has been published in Physical Review Letters.