Halting Molecules for Quantum Computers
In general, things are easier to manage when they are not moving but getting things to stop is not always that easy. This is as true of quantum mechanical particles as it is cars and children on a sugar-high, but you cannot grab onto a molecule and hold it still. Researchers at Northwestern University though, have found a way to start the tumbling of molecules, which could have implications for future quantum computers.
Over the decades, researchers have gotten pretty good at controlling atoms, but larger, more complex molecules are a different matter. Typically when you trap molecules, they will continue to rotate as though they were still freely moving, and some methods to stop them require cryostats to bring the temperature down to nearly absolute zero. The Northwestern researchers have instead developed a broadband laser that can stop a molecule in a fraction of a second. The key was in selecting the correct frequencies to cool the aluminum monohydride molecule down to just 4 K and its ground state, from room temperature. Shining a laser on molecules may not seem like a way to reduce the molecules' energy, but because of how the light frequencies interact with molecules, it is possible.
This new and elegant solution for bringing molecules to their ground state will likely see some use in quantum computing, but it does have other applications. Ultracold quantum-controlled chemistry could use the ability to control molecular rotors like this, and ground-state molecules could be used for testing if fundamental constants are constant throughout time.