Quantum mechanics tells us that no particle can ever be completely motionless. But how precisely can its orientation be controlled? Researchers at the University of Vienna, working with colleagues at TU Wien and Ulm University, have now cooled the rotational motion of a levitated silica nanorotor to its quantum ground state in two orientational degrees of freedom.
Writing in Nature Physics, the team shows that optical cooling can confine the particle’s orientation within the limits set by quantum zero-point fluctuations. These fluctuations represent the unavoidable uncertainty required by Heisenberg’s uncertainty principle.
Reaching this level of control marks a key step toward rotational matter-wave interferometry and highly sensitive quantum torque measurements.
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