Single-photon sub-Rayleigh precision measurements of a pair of incoherent sources of unequal intensity

• DOI: 10.48550/arxiv.2309.02295
• Publication Date: 2023-01-01
• Authors: Luigi Santamaria ...; Fabrizio Sgobba; Cosmo Lupo
• Keywords: Point spread function

Interferometric methods have been recently investigated to achieve sub-Rayleigh imaging and precision measurements of faint incoherent sources up the ultimate quantum limit. Here we consider single-photon two point-like emitters unequal intensity. This is motivated by fact that pairs natural will typically brightness, as for example binary star systems exoplanets. We address problems estimating transverse separation $d$ relative intensity $\epsilon$. Our theoretical analysis shows associated statistical errors are qualitatively different from case equal employ multi-plane light conversion technology experimentally implement Hermite-Gaussian (HG) spatial-mode demultiplexing (SPADE), demonstrate measurement with Gaussian point-spread function. The experimental comparable bounds. latter benchmarked against direct imaging, yielding a $\epsilon^{-1/2}$ improvement in signal-to-noise ratio, which may be significant when primary source much brighter than secondary one, However, achieving this improved scaling requires low noise implementation SPADE, affected crosstalk between HG modes.