This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Matter starts to behave differently at extremely low temperatures, creating conditions ideal for studying quantum physics and new states of matter. Now, researchers from China have achieved a new low-temperature record aboard their Tiangong space station.
Their research, recently published in Science, might lead to a new generation of experiments in quantum physics and precision measurements in space. At temperatures near absolute zero, atoms can form a kind of cloud, called a Bose–Einstein condensate (BEC), that behaves as a shared quantum wave. BECs are valuable for physics research.
The authors of the new study describe them as "versatile platforms for quantum simulation." The colder atoms get, the more they slow down, allowing scientists to take better measurements. This has led to a quest for lower and lower temperatures. But achieving extremely low temperatures near absolute zero can be difficult.
Gravity creates restrictions by making atoms sag in the trap. Magnetic levitation has been used to counteract gravity, but it creates a new issue by forcing atoms to have the same internal spin state. Optical traps use laser beams and offer more flexible control, but they had not directly produced a condensate under microgravity conditions before the new study.
The previous record low temperature was achieved using a drop tower to induce a free-fall state and reached an equivalent temperature of 38 picokelvin (a tiny fraction of one kelvin). Another space-based experiment at the International Space Station's Cold Atom Laboratory reached 52 picokelvin using magnetic trapping and matter-wave lensing. Scientists use the equivalent temperature, which describes the cloud's expansion energy and velocity, since an ordinary thermodynamic temperature is not practical for these kinds of experiments.
The team involved in the new study believed they could reach an even lower temperature by leveraging optical dipole traps (ODTs), which use focused laser beams to hold neutral atoms and microscopic particles in place. Doing this in space would allow for a microgravity environment that is not limited to short periods of time like drop-tower experiments. To reach their goal, the team cooled around 20,000 rubidium atoms with laser cooling and evaporative cooling, which removes higher-energy atoms, to create a condensate in an ODT.
Extract — continue reading at the source.
