Researchers at JILA, a joint institute of NIST and the University of Colorado Boulder, have created the coldest quantum gas of molecules to date. The gas, consisting of potassium-rubidium (KRb) molecules, reaches temperatures as low as 50 nanokelvin (nK) – just above absolute zero. This ultra-cold gas exhibits quantum mechanical wave patterns rather than classical particle behavior.
The key to achieving this record-low temperature lies in the precise control over the molecules’ energy states. The potassium atom is a fermion (with an odd number of subatomic components), while the rubidium atom is a boson (with an even number of subatomic components). The resulting molecules have a Fermi character. JILA researchers improved their cooling techniques and conversion efficiency to create a higher concentration of molecules in the lowest-energy state.
The new gas is the first to reach a temperature where quantum effects dominate over classical behavior, and the molecules exhibit quantum degeneracy – a state where their matter waves overlap, creating a new collective quantum entity. This allows scientists to study how electric fields affect the polar interactions of the molecules.
Potential applications of this research include new chemical processes, quantum computing using charged molecules as quantum bits, and precision measurement tools like molecular clocks. The process involves creating weakly bound KRb molecules using a precisely tuned magnetic field, then converting them to tightly bound molecules using near-infrared and red laser light.
Source: https://www.nist.gov/news-events/news/2019/02/jila-researchers-make-coldest-quantum-gas-molecules
Keywords: Quantum, Molecules, Degeneracy, Fermi, Ultra-low
