Bonn 2025 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 45: Mechanical, Macroscopic, and Continuous-variable Quantum Systems (joint session QI/Q)

Q 45.1: Hauptvortrag

Mittwoch, 12. März 2025, 14:30–15:00, HS IX

Wave-Function Expansion with Optically Levitated Nanoparticles — •Martin Frimmer — ETH Zürich, Zürich, Switzerland

Optomechanical systems provide testbeds for applications ranging from quantum information processing to fundamental searches for potential limitations of quantum theory with increasingly large masses. All quantum optomechanical protocols require purification of the motional state of the mass under scrutiny. Staying in the realm of Gaussian states, the only pure state of motion of a harmonic oscillator is the quantum ground state. Accordingly, ground-state cooling has been the main aim of the opto-mechanics community. It has been achieved with the help of laser cooling and, for the vast majority of experiments, of cryogenic cooling. Only recently, first systems have demonstrated quantum optomechanics at room temperature. A promising experimental platform in this context are optically levitated nanoparticles. Their center-of-mass motion and also their orientation (in case of optically anisotropic particles) resemble harmonic-oscillator degrees of freedom of mechanical motion. In our work, we prepare the highest-purity opto-mechanical oscillator to date. By coupling the rotational degree of freedom of an optically levitated nano-cluster to an optical cavity, we cool the libration mode to a phonon occupation of 0.04 quanta. Notably, we set this purity record in a room-temperature experiment, opening the door towards high-purity quantum optomechanics without the need for cryogenic cooling.

Keywords: optomechanics; optical levitation; optical trapping; quantum measurement; quantum control