How low can they go? Almost as low as you can go, it seems. For the first time, transistors of the sort used in computers, smartphones and other consumer devices have been tested successfully at temperatures a whisker above absolute zero.

Transistors are electronic components that act as switches to control current. Their performance is affected by temperature, so specially designed versions are used in super-cold conditions.  They are costly and difficult to obtain, however, and complicated circuitry or additional equipment is often needed as well.

from the Institute of Research into the Fundamental Laws of the Universe in Gif-Sur-Yvette, France, and his team wanted to see if off-the-shelf transistors could be used instead. If so, it would make research at these temperatures dramatically easier.

The team is developing the next generation of infrared cameras for use in outer space. For maximum sensitivity, they need to operate at the lowest temperatures we can achieve – just above -273°C. And the electronics they bolt on to read their sensors need to hold up as well.

Theory predicted that ordinary transistors would work at such temperatures, but testing them was a different matter. It took three days to cool down their equipment to the target temperature, and they had to use a special set-up to stabilise it – preventing current in the transistors from heating them up, for example.

The tests confirmed that the transistors stood up well to the extreme conditions. Malik Mansour at the University of Paris-Saclay in Saint-Aubin, France is impressed. “It’s difficult to make measurements at such low temperatures,” he says.

Medical uses

Mansour thinks that the results could also be relevant to medical imaging, opening up the possibility of achieving more detailed pictures with supercooled instruments. The whole idea is expensive and complicated at present, but he thinks that it could become feasible in the future. “Cryotechnology will be improved,” he says.

Researchers developing quantum computers have also expressed interest in the results. Rhouni’s team, however, is focused on using the technology on the , slated to launch in the late 2020s, to investigate the coldest regions of the universe. During the 15 years ago, they discovered that these star-forming regions are dominated by filaments of gas and dust. Now they want to investigate the role of the filaments using specialised detectors and explain their shape. “We will need to describe their magnetic field,” says Vincent Reveret, a member of the team. “It has never been done before.”

Perpetual motion machines

Time crystals: A new state of matter that outlasts the universe

A bizarre oscillating material that seems to run on a never-ending loop has apparently been made in the lab, bending the cast-iron laws of thermodynamics

Teleporters

Invisibility cloaks

Negative temperatures

Matter married with antimatter

Call it the big chill. Laser cooling has tackled its biggest molecule yet, bringing the temperature of a three-atom molecule to within a thousandth of a kelvin of absolute zero for the first time. The feat could eventually be used to build molecular quantum computers.

Physicists have been laser cooling individual atoms since the 1970s, but it’s much harder to apply it to molecules. The technique works by causing an electron bound to the atom (or molecule) to release photons, which relies on matching the system’s energy levels with those of the cooling lasers. The more atoms a molecule contains, the more complex its vibrations and rotations, making it difficult to achieve a match.

and his team at the MIT-Harvard Center for Ultracold Atoms have now managed to use lasers to cool molecules of strontium monohydroxide. Now that his team has shown it works with three-atom molecules, Kozyryev thinks the technique could be extended to molecules with up to around 15 atoms.

Such ultra-cool molecules could form the basis of molecular quantum computers, he says. “You can actually use laser light not only to cool atomic molecules but to redial their state precisely.” If physicists can control which parts of a molecule are vibrating, they could use this technique to store information.

Cooling molecules to such low temperatures is extremely tricky, so these results are impressive, says at the University of Birmingham, UK. But Boyer does not expect it to lead to molecular quantum computers in the near future as progress in this area has been so slow. “We’re not going to get laser-cooled complex molecules any time soon,” he says.

However, the technique could also be useful to chemists, says Boyer. Molecules cooled close to absolute zero would react much more slowly, potentially allowing researchers to observe reactions at much greater levels of detail than currently possible, he says.

“We can chart the whole evolution of the Boomerang Nebula, which I think is unprecedented”