LEvitated MAgnets for QUantum Metrology

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Levitated micromagnets have been theoretically proposed as building blocks of a number of hybrid quantum systems and as ultralow-noise sensors of torque, force or magnetic field, capable of largely outperforming conventional quantum-limited devices in terms of energy resolution. This outstanding potential is supported by recent pioneering experiments, yet it is far from being fully demonstrated. In this project we aim at a systematic investigation of sensors based on levitated micromagnets. We will explore various levitation platforms, such as superconducting traps based on the Meissner effect, on-chip circuits for magnetic trapping, free-fall, and Paul traps for charged micromagnets, and exploit coupling to different quantum systems or devices, such as diamond Nitrogen-Vacancy (NV) centers and SQUIDs. We will primarily investigate the librational and rotational motion of the levitated magnets and focus on the detection of ultralow torque and magnetic fields, with the goal of demonstrating unprecedented energy resolution. In particular, we aim at demonstrating the most sensitive regime corresponding to atom-like Larmor precession of a mesoscopic magnet, a peculiar effect arising from the quantum nature of intrinsic spin. Theoretically we expect to achieve outstanding improvement over the state of the art in terms of energy resolution. For instance, we expect to overcome by orders of magnitude the Energy Resolution Limit, a semiempirical bound which appears to be satisfied by all existing quantum magnetometers. We will then exploit the potential of the developed sensors in specific science cases of great interest in fundamental physics, such as probing exotic interactions arising from new physics beyond the standard model. As a long-term vision, we will investigate the potential for future tests of General Relativity with quantum spin systems (specifically, levitated magnets) in space. We aim at an initial proof-of-principle demonstration in the Einstein-Elevator, where the Larmor precession of a free-falling magnet can be observed in the cleanest conceivable way. The project will benefit from the highly transversal and interdisciplinary nature of the consortium, which gathers scientists converging to levitated quantum magnetomechanics from the diverse fields of diamond NV centers, ion traps, cold atoms, hybrid quantum systems, SQUIDs, optomechanics and optical magnetometry.