Goldberg, Aaron Z.Klimov, Andrei B.Leuchs, GerdSánchez Soto, Luis Lorenzo2023-06-172023-06-172021-042515-764710.1088/2515-7647/abeb54https://hdl.handle.net/20.500.14352/8086© 2021 The Author(s). We are indebted to G Björk, F Bouchard, C Chryssomalakos, M Grassl, P de la Hoz, E Karimi, and K Z˙ yczkowski for discussions.We acknowledge financial support from the European Union Horizon 2020 (Grants ApresSF and Stormytune), the Ministry of Education and Science of the Russian Federation (Mega-Grant No. 14.W03.31.0032), the Mexican CONACYT (Grant No. 254127), and the Spanish MINECO (Grant No. PGC2018-099183-B-I00). AZG acknowledges funding from an NSERC Discovery Award Fund, an NSERC Alexander Graham Bell Scholarship, the Walter C Sumner Foundation, the Lachlan Gilchrist Fellowship Fund, a Michael Smith Foreign Study Supplement, and Mitacs Globalink.Conventional classical sensors are approaching their maximum sensitivity levels in many areas. Yet these levels are still far from the ultimate limits dictated by quantum mechanics. Quantum sensors promise a substantial step ahead by taking advantage of the salient sensitivity of quantum states to the environment. Here, we focus on sensing rotations, a topic of broad application. By resorting to the basic tools of estimation theory, we derive states that achieve the ultimate sensitivities in estimating both the orientation of an unknown rotation axis and the angle rotated about it. The critical enhancement obtained with these optimal states should make of them an indispensable ingredient in the next generation of rotation sensors that is now blossoming.engAtribución 3.0 Españahttps://creativecommons.org/licenses/by/3.0/es/journal articlehttps://doi.org/10.1088/2515-7647/abeb54https://iopscience.iop.orgopen access535Quantum sensingEstimation theoryRotation sensorsUltimate limitsÓptica (Física)2209.19 Óptica Física