![Adaptive quantum measurement framework and exoplanet detection challenge. (a) Schematic of the proposed method. Photons from an unknown multi-source scene are projected by an adaptive mode sorter onto a basis {ϕ1, . . . , ϕM} maximizing QFI for the current scene estimate and read out as photon counts {n1, . . . ,nM}. These counts drive a maximum-likelihood update of the source parameters (xn, yn, bn), from which the basis is reconstructed to maximize the quantum Fisher information, closing the measure–estimate–adaptive mode calculation loop. (b) Photon-level view of the detection problem as the host– companion contrast deepens from 1:102 to 1:106 (105 photons per panel; red and yellow points denote stellar and planetary photons, crosses mark true positions). The planetary cluster, recognizable at 1:102 , is progressively buried in the stellar halo and becomes unrecognizable, illustrating the failure of direct imaging in the ultra-high-contrast regime. -- [astro-ph.IM]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/07/Exoplanet-Detection-Using.png?fit=1200%2C679&ssl=1)
[astro-ph.IM] Detecting terrestrial exoplanets in the habitable zones of nearby stars remains a critical challenge. Such planets can be 10^8 10^10 times fainter than their host stars and lie at diffraction-limited angular separations, where starlight strongly obscures the companion signal.
Here we present an adaptive quantum measurement method for estimating the number, positions, and brightnesses of mutually incoherent point sources in the sub-Rayleigh, ultra-high-contrast regime, operating at contrasts down to 10^-8 — five orders of magnitude beyond previous quantum imaging approaches to exoplanet detection. The method adopts a spatial-mode basis that is updated to maximize the quantum Fisher information per detected photon.
Estimation is performed by maximum likelihood in log-brightness coordinates, and the source count is determined by Bayesian-information-criterion (BIC) model selection directly from photon-count statistics, without a tunable detection threshold. For point sources within sub-Rayleigh separations and with brightness ratios spanning eight orders of magnitude, the method reconstructs complete scenes with a mean success rate of 72.5%.
Furthermore, it is robust to misalignment, maintaining a 71.3% success rate under offsets of up to six pixels. These results demonstrate that terrestrial exoplanets can be detected below the Rayleigh limit, a regime previously inaccessible to direct imaging.
Hyunsoo Choi, Hyoung Won Baac, Zubin Jacob, Haejun Chung
Subjects: Optics (physics.optics); Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2607.06931 [physics.optics] (or arXiv:2607.06931v1 [physics.optics] for this version)
https://doi.org/10.48550/arXiv.2607.06931
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Submission history
From: Haejun Chung
[v1] Wed, 8 Jul 2026 02:50:38 UTC (2,720 KB)
https://arxiv.org/abs/2607.06931
Astrobiology,
