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Ultracold Rubidium Atoms Experiment Shows Time Emerging from Quantum Interactions
@NewScientist reported that Giovanni Barontini cooled 20,000 rubidium atoms near absolute zero and divided them into bright and dark sectors. Lasers induced atom exchanges that altered entropy and defined an internal time matching Schrödinger equation predictions.
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Giovanni Barontini at the University of Birmingham cooled around 20,000 rubidium atoms to temperatures close to absolute zero using lasers and electromagnetic forces. He divided the atoms into two sectors labeled bright and dark. Lasers then induced quantum-level exchanges of atoms between the sectors.
The exchanges altered the entropy of the system. Barontini defined an internal time for the toy universe based on the direction of increasing entropy. He inserted this time into the Schrödinger equation and calculated the atoms’ quantum states, which matched the experimental measurements.
Nevill Mott first proposed in the 1930s that time could arise from quantum correlations. In 2013 Marco Genovese and colleagues at the National Metrology Institute of Italy demonstrated the concept with entangled photons. The new work extends that approach to a more complex atomic system and applies the Schrödinger equation with the derived internal time.
Claus Kiefer at the University of Cologne said the experiment connects to efforts to combine gravity and quantum theory. Carlo Rovelli at Aix-Marseille University said the setup relies on already-understood physics and cannot reveal new features of time. The study was published in Physical Review Research with DOI 10.1103/1h9j-df4k.
