Quantum-Correlation-Based Multi-Emitter Localization in Information-Limited Regimes via Learned Inference

Abstract

Quantum correlation measurements have emerged as a powerful tool for localizing multiple emitters with subwavelength separation. Multi-emitter localization consists of two distinct tasks: identifying the emitter count $N$ and estimating their positions $\left\{x^{i}\right\}$. Existing fit-and-select frameworks fit the measured intensity and autocorrelation data using several models corresponding to different values of $N$ and then select the best-supported model. This procedure lets errors from the multi-parameter optimization of emitter positions propagate into the choice of model, degrading performance under photon-limited and high-background conditions. We propose a method that directly infers the emitter count and positions from the multimodal data via learned inference. Learned inference improves both the emitter-counting accuracy and localization precision compared to the fit-and-select method. It achieves more than tenfold improvement in precision and requires up to five times fewer photons to achieve practically meaningful localization with the largest gains observed under low photon counts, strong background, narrowly spaced emitter configurations, and spatially truncated data. This photon-efficient quantum-assisted localization framework offers a promising route toward real-time biological imaging and single-particle tracking in densely labeled samples.