Researchers predict a fractional Fermi sea beyond standard quantum theory
A team led by the University of Innsbruck’s Nägerl group and theorist Alvise Bastianello predicts that cycling ultracold caesium atoms between strong attraction and repulsion can produce a highly excited but ordered state. The researchers call it a fractional Fermi sea; its correlations differ from those predicted by Tomonaga–Luttinger liquid theory. The study is theoretical, while a companion paper on experimental realization is under review.
Bottom line — The proposed state’s Friedel oscillations and unusual correlation patterns distinguish it from the established one-dimensional model.
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The calculations start with atoms in their ground state and drive them into a highly excited configuration without erasing their order, according to the University of Innsbruck.
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The name refers to a modified rule for how particles occupy quantum states, the researchers explain.
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The study predicts pronounced Friedel oscillations and distinctive patterns in how correlations decay, including at weak repulsion.
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The work was published in Physical Review Letters; the Innsbruck group says the experimental companion paper is under review.