An ultracold atomic cloud is comparable to a motel with a neon “no vacancy” sign.
A visitor to the motel is out of luck if they want to change rooms. There are no availNormal conditions result in easy interactions between atoms and light. If you direct a light beam toward an atom cloud, some of the light will be scattered in all directions. This kind of light dispersion is a typical occurrence; it takes place in the atmosphere of Earth. We perceive the sky as blue because of the sun’s scattered radiation, according to Yair Margalit, a member of the MIT team that carried out one of the trials.
But in extremely cold, dense atom clouds, quantum physics becomes more prominent. According to physicist Amita Deb, a co-author of one of the research from the University of Otago in Dunedin, New Zealand, “the way they interact with light or scatter light is different.”
able accommodations, therefore one must remain put. Similarly, in recent investigations, atoms confined by dense circumstances are unable to change their quantum states. According to three research teams’ findings published in the Nov. 19 Science, this restriction prevents the atoms from scattering light as they typically would. This effect has now been observed for the first time after being predicted more than three decades ago.
Atoms in the experiments can’t adopt the same quantum state, or, more specifically, they can’t have the same momentum as another atom in the experiment, in accordance with the Pauli exclusion principle (SN: 5/19/20). A dense cloud of atoms chilled to almost absolute zero will cause them to enter the lowest-energy quantum states. There won’t be any open rooms in those low-energy situations, making them resemble a hotel.
An atom that scatters light gains speed and changes its quantum state as it transmits light in a different direction. However, the atom won’t scatter the light if the crowded circumstances prevent it from changing its state. As the atom cloud grows clearer, light passes through instead of being scattered.
Margalit and associates measured the amount of light scattered as they shone light through a cloud of lithium atoms to examine the outcome. The temperature was then lowered, causing the atoms to occupy the lowest energy states and decreasing light scattering. The atoms’ light scattering decreased by 37% as the temperature lowered, showing that many of the atoms were no longer able to do so. (Some atoms can still scatter light, for instance, if they are propelled into vacant higher-energy quantum states.)
In a different experiment, physicist Christian Sanner of the Boulder, Colorado-based research center JILA and associates examined a cloud of extremely cold strontium atoms. The amount of light scattered at tiny angles, where the atoms are less likely to be moved by the light and thus more unlikely to be able to find an unoccupied quantum state, was measured by the researchers. The atoms dispersed half as much light at lower temperatures as they did at higher ones.
In the third experiment, Deb and Niels Kjaergaard, a physicist from the University of Otago, measured a similar scattering drop in an ultracold potassium atom cloud and a matching rise in the amount of light that was transmitted through the cloud.
The structure of atoms and the existence of matter as we know it is determined by the Pauli exclusion principle, which also controls the behavior of electrons, protons, and neutrons. According to Sanner, these fresh findings present the general idea in a fresh setting. It’s fascinating because it exemplifies a fundamental law of nature.
The research makes fresh recommendations for manipulating atoms and light. Theoretical physicist Peter Zoller of the University of Innsbruck in Austria, who was not involved in the study, thinks that “one could imagine a lot of interesting applications.” Light scattering is particularly connected to a process known as spontaneous emission, in which an atom emits light to transition from a high-energy state to a lower energy state. The findings imply that degradation might be stopped, lengthening the energetic state’s lifetime. A quantum computer, for instance, may make use of such a technology to store quantum information over longer periods of time than is typically feasible.
These uses are only theoretical at this time, according to Zoller. Future research should examine how plausible these are.