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Acoustic frequency atomic spin oscillator in the quantum regime
preprintposted on 2023-03-22, 16:01 authored by Jun Jia, Valeriy Novikov, Tulio Brito Brasil, Emil Zeuthen, Jörg Helge Müller, Eugene S. Polzik
We experimentally demonstrate quantum behavior of a macroscopic atomic spin oscillator in the acoustic frequency range. Quantum back-action of the spin measurement, ponderomotive squeezing of light, and oscillator spring softening are observed at spin oscillation frequencies down to 6 kHz. Quantum noise sources characteristic of spin oscillators operating in the near-DC frequency range are identified and means for their mitigation are presented. These results constitute an important step towards quantum noise reduction and entanglement-enhanced sensing in the acoustic range using a negative-mass reference frame. In particular, the results are relevant for broadband noise reduction in gravitational wave detectors.