(ScienceDaily) Researchers show that a quantum sensor using a single atom can accurately measure the coldest places in the universe. In a collaboration between the Okinawa Institute of Science and Technology Graduate University (OIST), University College Dublin and Trinity College Dublin, researchers have described a quantum process that uses a single atom as a thermometer to sensitively measure the temperature of an ultra-cold gas.
“As quantum physicists, our ultimate goal is to create and measure systems as close as possible to absolute zero. This is the lowest temperature limit, around -273°C or zero on the Kelvin temperature scale, and it’s when particles stop moving. These ultra-cold systems are important for successfully harnessing quantum technologies or reducing noise in quantum experiments,” said Professor Thomas Busch, head of the Quantum Systems Unit at OIST and co-author of the study, published as an Editor’s Suggestion in Physical Review Letters. “So being able to detect minute changes in temperature, at only tens of billionths of a degree above zero kelvin, is critical.”
The team is now exploring numerous paths to improve the method’s sensitivity, such as by using machine learning to optimize the interactions between the thermometer atom and the gas, or by introducing more thermometer atoms into the system so more complex quantum interactions can occur.
“This new method has pushed the bounds of thermometry, which has important applications for quantum technology,” concluded Prof. Busch. “I expect that we are going to see it being used very soon in experiments.”

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