Scientists have reportedly achieved the lowest equivalent temperature ever recorded in space, according to a team conducting experiments aboard China’s Tiangong space station.
The researchers say they successfully cooled a cloud of atoms to temperatures of just 9.7 picokelvins above absolute zero, in a breakthrough that could pave the way toward new applications in quantum physics research.
The findings, which were recently reported in the journal Science, represent close to a fourfold improvement over previous record temperatures of around 38 picokelvin, which were achieved during experiments with a terrestrial drop tower.
New Record Low Temperature Recorded
To achieve these extraordinary temperatures, researchers cooled approximately 20,000 rubidium atoms using a combination of laser cooling and evaporative cooling, which created what physicists call a Bose-Einstein condensate—an uncommon state of matter in which atoms engage in unusual behaviors that seem to resemble those of a single quantum wave.
Next, the researchers transferred the atoms into a specialized “trap” involving an optical dipole, which relies on focused laser beams to confine particles. To achieve this, the researchers gradually weakened the trap, which allowed it to reduce the energy expansion of the atoms.
Of key importance, operating within the microgravity conditions aboard the Tiangong space station allowed the researchers to overcome normal limitations imposed by Earth’s gravity. Additionally, this allowed them to observe the atomic cloud’s expansion for a total of seven seconds, which was far longer than durations achieved in experiments on Earth.
Paving the Way Toward New Physics Possibilities
With a resulting equivalent temperature of just 9.7 picokelvin—in other words, around just 0.0000000000097 kelvin—the researchers now believe their achievement, determined through careful measurements of the cloud’s expansion, as opposed to traditional thermodynamic measurements, may help to enable more precise quantum measurements.
Additionally, the team says investigations of exotic states of matter and advanced space-based atom interferometers could also be among the applications their findings may help facilitate.
Overall, such instruments, the Chinese researchers say, may eventually help scientists to test fundamental principles of the physical world, which include Einstein’s famous equivalence principle, which involves the subtle relationship between acceleration and gravity.
The team’s findings were reported in the recent paper, “Quantum gases below 10 picokelvin in space,” which appeared in the journal Science.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.