A quantum thermometer to measure the coldest temperatures

In Situ Thermometry of a Cold Fermi Gas via Dephasing Impurities

Physicists from Trinity College Dublin have proposed a thermometer based on quantum entanglement that can accurately measure temperatures a billion times colder than those in outer space.

These ultra-cold temperatures arise in clouds of atoms, known as Fermi gasses, which are created by scientists to study how matter behaves in extreme quantum states.

Technically speaking, their proposal involves creating a quantum superposition: a weird state where the probe atom simultaneously does and doesn’t interact with the gas. They showed that this superposition changes over time in a way that is very sensitive to temperature.

Their results have just been published in the journal Physical Review Letters.

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