Scientists Make the Coldest Large Molecule on Record

In a new discovery, scientists have developed a unique four-atom molecule, colder than any seen before.

This strange molecule, formed from sodium-potassium in an unusual arrangement, boasts an exceptionally lengthy chemical bond. It was produced at a temperature of 134 nanokelvin, which is a mere 134 billionths of a degree above absolute zero. The research detailing this ultracold substance was published on January 31 in the journal Nature.

Understanding quantum behavior is vital, especially in ultracold systems. Quantum mechanics, the laws that govern tiny particles, become prominent at low temperatures.

These setups allow scientists to finely tune particle energies to create quantum simulations. These simulations mimic other complex quantum systems, helping in our comprehension of physics beyond our current grasp, as reported by Live Science.

For example, looking into the quantum characteristics of ultracold molecules might eventually help scientists pinpoint the specific material properties crucial for developing high-temperature superconductors.

Balancing simplicity and complexity in ultracold systems

A challenge arises when balancing simplicity and complexity in ultracold systems. If a system is too basic, it might not accurately represent the full spectrum of behavior seen in intricate quantum systems. However, introducing more complexity makes designing effective experiments more difficult.

Roman Bause, a quantum optics researcher at the University of Groningen in the Netherlands, explained this challenge.

He mentioned, “Usually people use atoms or ions and what makes them somewhat controllable is the fact that you have a relatively limited number of quantum states.”

“But if I draw all the quantum states of a molecule, it will fill quite a thick book. It’s a factor of a million or so more states,” Bause further added.

The abundance of additional quantum states presents intriguing questions in the world of quantum mechanics. However, it also complicates the process of cooling the molecules.

Record-breaking coldest molecules

In a recent study, Tao Shi, a physicist from the Chinese Academy of Sciences, along with international colleagues, devised a solution. They used a multi-step cooling process, starting with laser cooling to produce the record-breaking molecules.

This cooling technique involves directing laser beams from various directions toward a moving atom. The atom absorbs the light, becoming excited in a quantum state, and then promptly releases energy to revert to its original state.

Due to the atom’s movement in relation to the laser beams, known as the Doppler effect, it releases slightly more energy than it absorbs, resulting in self-cooling, as reported by Live Science.

“The problem with using this technique for molecules is that there’s not just one ground state. You would potentially need thousands of laser beams and it’s just too much technical effort,” Bause said.