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  • Open Access

Quantum limits of exoplanet detection and localization

Nico Deshler1,*, Sebastiaan Haffert2,†, and Amit Ashok1,‡

  • 1Wyant College of Optical Sciences, University of Arizona, 1630 East University Boulevard, Tucson, Arizona 85721, USA
  • 2Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands

  • *Contact author: ndeshler@arizona.edu
  • †Contact author: haffert@strw.leidenuniv.nl
  • ‡Contact author: ashoka@arizona.edu
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Phys. Rev. A 113, 042406 – Published 1 April, 2026

DOI: https://doi.org/10.1103/g6kr-mqdj

Abstract

Discovering exoplanets in orbit around distant stars via direct imaging is fundamentally impeded by the combined effect of optical diffraction and photon shot noise under extreme star-planet contrast. Coronagraphs strive to increase the signal-to-noise ratio of exoplanet signatures by optically suppressing light from the host star while preserving light from the exoplanet. However, it is unclear whether direct-imaging coronagraphs constitute an optimal strategy for attaining fundamental limits relevant to exoplanet discovery. In this work, we first review the quantum information limits of exoplanet detection and localization characterized by (1) the quantum Chernoff exponent for symmetric hypothesis testing, (2) the quantum relative entropy for asymmetric hypothesis testing, and (3) the quantum Fisher information matrix for multiparameter estimation. We demonstrate that coronagraphs designed to completely suppress light in the fundamental mode of the telescope, while perfectly transmitting higher-order orthogonal modes, indeed achieve these limits in the regime of high star-planet contrasts. Furthermore, we formulate coronagraphs as quantum channels, thus generalizing the classical framework of coronagraphy to the quantum setting. Using this framework, we compare the information-theoretic performance of leading coronagraph designs against the quantum limits. Our analysis indicates that quantum-optimal coronagraphs offer enhanced information efficiency in the subdiffraction regime compared to leading coronagraph designs and may significantly expand the domain of accessible exoplanets.

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Phys. Rev. A 113, 042406– Published 1 April, 2026
  • Received 1 July 2025
  • Accepted 11 November 2025
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