Quantum mechanics tells us that a particle can never be perfectly still. But how precisely can it be oriented? A research team at the University of Vienna, together with colleagues at TU Wien and Ulm University, has now cooled the rotational motion of a levitated silica nanorotor all the way to its quantum ground state - in two orientational degrees of freedom. Reporting in Nature Physics, they show how optical cooling confines the nanoparticle's orientation to within the bounds of quantum zero-point fluctuations, the unavoidable orientational uncertainty imposed by Heisenberg's uncertainty principle. Such quantum-limited alignment is an important milestone towards rotational matter-wave interferometry and ultra-sensitive quantum torque sensing.Quantum Ground State of Rotation: for the First Time in Two Dimensions
April 25, 2026
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Quantum mechanics tells us that a particle can never be perfectly still. But how precisely can it be oriented? A research team at the University of Vienna, together with colleagues at TU Wien and Ulm University, has now cooled the rotational motion of a levitated silica nanorotor all the way to its quantum ground state - in two orientational degrees of freedom. Reporting in Nature Physics, they show how optical cooling confines the nanoparticle's orientation to within the bounds of quantum zero-point fluctuations, the unavoidable orientational uncertainty imposed by Heisenberg's uncertainty principle. Such quantum-limited alignment is an important milestone towards rotational matter-wave interferometry and ultra-sensitive quantum torque sensing.
