2016/04/30 by Ranjith Nair, Mankei Tsang · 2 citations
Physics and Astronomy · #quant-ph #physics.optics
paper · pdf · doi:10.1103/physrevlett.117.190801
published as Phys. Rev. Lett. 117, 190801 (2016) · Close approximation to the published version + Supplementary Material (13 pages, 6 figures)
arxiv created 2016/11/28 · arxiv updated 2016/11/29
We obtain the ultimate quantum limit for estimating the transverse separation of two thermal point sources using a given imaging system with limited spatial bandwidth. We show via the quantum Cramér-Rao bound that, contrary to the Rayleigh limit in conventional direct imaging, quantum mechanics does notmandate any loss of precision in estimating even deep sub-Rayleigh separations. We propose two coherent measurement techniques, easily implementable using current linear-optics technology, that approach the quantum limit over an arbitrarily large range of separations. Our bound is valid for arbitrary source strengths, all regions of the electromagnetic spectrum, and for any imaging system with an inversion-symmetric point-spread function. The measurement schemes can be applied to microscopy, optical sensing, and astrometry at all wavelengths.