On the 29th, the international scientific journal Nature published a model of an antenna standing frozen on a laboratory table and a model of molecules floating around it on the cover. The molecular model floating around the antenna looks like a cluster of icicles.
In chemistry, polar molecules are the best candidates for studying quantum effects. Molecules are easy to observe because the internal structure can be examined in detail. If molecules are classified according to their polarity, they can be divided into nonpolar molecules in which the sum of dipole moments is zero and polar molecules in which the sum of dipole moments is not zero. The dipole moment means that they are in charge states of the same magnitude and different signs even when they are separated from each other. Molecules with this property can interact over long distances. In the case of atoms, another tool for observing quantum effects, they must collide with each other in order to interact.
The problem is that in order to properly observe quantum effects through molecules, the molecules must first be sufficiently cooled. Energy is at its minimum at absolute 0 degrees (-273 degrees below zero), and in this state, particles move slowly and can be controlled and studied one by one. However, the intrinsic collisional motion of the molecules acted as a factor preventing cooling.
Andreas Sindewolf, a researcher at the Max Planck Institute for Quantum Optics in Germany, and his colleagues introduced to Science on this day the achievement of cooling polar molecules to reach ‘quantum degeneration’, a state where quantum effects can be best observed. Degeneracy refers to the existence of two or more states for one energy level in quantum mechanics.
To cool the polar molecules, the team first used microwaves to wrap a repelling barrier around them. Molecules surrounded by the barrier did not cause a loss-causing reaction when cooled to cryogenic temperatures. Instead, it caused an inelastic collision in which the kinetic energy before and after the collision is not conserved. Through this process, the molecule was safely cooled to 21 nanokelvin (1 nK, 1 billionth of K). It is frozen infinitely close to 0K.
The research team said, “Cold-frozen polar molecules exhibit a polyhedral phenomenon (
It will pave the way for exploring the phenomenon in which particles or objects that can be seen as particles continue to move while exerting force on each other.”