Řeháček, J.Stoklasa, BohumilKoutný, DominikHradil, ZdenekSánchez Soto, Luis Lorenzo2023-06-162023-06-162019-11-070031-900710.1103/PhysRevLett.123.193601https://hdl.handle.net/20.500.14352/6020© 2019 American Physical Society. We thank Robert W. Boyd for helpful discussions. We acknowledge financial support from the Czech Science Foundation (Grant No. 18-04291S), the Technology Agency of the Czech Republic (Grant No. TE01020229), the Palacky University (Grant No. IGA_PrF_2019_007), and the Spanish MINECO (Grants No. FIS2015-67963-P and No. PGC2018-099183-B-I00).We derive fundamental precision bounds for single-point axial localization. For Gaussian beams, this ultimate limit can be achieved with a single intensity scan, provided the camera is placed at one of two optimal transverse detection planes. Hence, for axial localization there is no need of more complicated detection schemes. The theory is verified with an experimental demonstration of axial resolution 3 orders of magnitude below the classical depth of focus.engIntensity-based axial localization at the quantum limitjournal articlehttp://dx.doi.org/10.1103/PhysRevLett.123.193601https://journals.aps.orgopen access535Fluorescence microscopyÓptica (Física)2209.19 Óptica Física