A macroscopic object passively cooled into its quantum ground state of motion beyond single-mode cooling

• DOI: 10.1038/s41467-021-26457-8
• Publication Date: 2021-10-26T10:03:16Z
• Authors: D. Cattiaux; I. Golokolenov; S. Kumar; M. Sillanpää; L. Mercier de Lép...; R. R. Gazizulin; X. Zhou; A. D. Armour; O. Bourgeois; A. Fefferman; E. Collin
• Keywords: 0301 basic medicine; Quantum Physics; Condensed Matter - Mesoscale and Nanoscale Physics; Science; Q; 500; FOS: Physical sciences; 530; 01 natural sciences; 7. Clean energy; [PHYS.PHYS.PHYS-GEN-PH]Physics [physics]/Physics [physics]/General Physics [physics.gen-ph]; Article; 03 medical and health sciences; 13. Climate action; Mesoscale and Nanoscale Physics (cond-mat.mes-hall); 0103 physical sciences; Quantum Physics (quant-ph)

The nature of the quantum-to-classical crossover remains one most challenging open question Science to date. In this respect, moving objects play a specific role. Pioneering experiments over last few years have begun exploring quantum behaviour micron-sized mechanical systems, either by passively cooling single GHz modes, or adapting laser techniques developed in atomic physics cool low-frequency modes far below temperature their surroundings. Here instead we describe very different approach, passive whole micromechanical system down 500 μK, reducing average number quanta fundamental vibrational mode at 15 MHz just 0.3 (with even lower values expected for higher harmonics); challenge being be still able detect motion without disturbing noticeably. With such an approach harmonics and surrounding environment are also cooled, leading potentially much longer coherence times, enabling questioning wave-function collapse, from gravitational background, thermodynamics. Beyond behaviour, here report on fluctuations device in-equilibrium with cryostat. These reveal surprisingly complex interplay local allow characteristics two distinct thermodynamic baths probed.