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Optics Express

Improving the precision and efficiency of an optical telescope array by the piecemeal method

Jian Leng, Yi-Xin Shen, Zhou‐Kai Cao, Xiangbin Wang

Published Dec 15, 2025• 2 citations
Publisher

Abstract

Angular localization of remote optical objects is a fundamental challenge in fields such as remote sensing and astrometry. We propose the piecemeal method for a telescope array, with explicit formulas showing its key advantages strictly: higher precision, efficiency, and robustness, which are further confirmed by numerical simulations. Specifically, our method achieves a 10 4 precision improvement with 10 5 photon number reduction compared to existing telescope arrays, and achieves precision improvements of 10 3 and 10 2 over the Gaia telescope and the ultimate quantum limit for incoherent imaging, respectively, under comparable photon numbers. We have also presented a reference-object-based implementation framework for our method that seamlessly integrates with existing optical interferometric systems.

DOI
10.1364/oe.582665

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Optics Express•Mar 16, 2026•0 citations
Angular localization of remote optical objects is a fundamental challenge in fields such as remote sensing and astrometry. We propose the piecemeal method for a telescope array, with explicit formulas showing its key advantages strictly: higher precision, efficiency, and robustness, which are further confirmed by numerical simulations. Specifically, our method achieves a 10 4 precision improvement with 10 5 photon number reduction compared to existing telescope arrays, and achieves precision improvements of 10 3 and 10 2 over the Gaia telescope and the ultimate quantum limit for incoherent imaging, respectively, under comparable photon numbers. We have also presented a reference-object-based implementation framework for our method that seamlessly integrates with existing optical interferometric systems.
Abstract Precise angular estimation of remote targets is a fundamental task in optical interferometry, particularly in the weak-light regime where photon resources are limited. Interferometric schemes employing multiple telescopes can overcome the diffraction limit of a single aperture but are often highly sensitive to experimental imperfections. In this work, we study a piecemeal interferometric approach that jointly exploits measurement data from multiple baselines for angular estimation, and we relax the constraints on baseline configurations. The proposed scheme remains effective even with a reduced number of baselines, highlighting its practical applicability. Focusing on realistic experimental conditions, we analyze the impact of baseline length and orientation errors on the estimation performance. We show that both the original and generalized piecemeal protocols exhibit strong robustness against these imperfections and achieve higher angular estimation precision than existing single-baseline weak-light interferometric schemes under identical practical conditions.
The idea of exploiting quantum features of light to perform more precise astrophysical measurements is a long-desired goal of both the optics and astrophysics communities, but only recently have theoretical proposals started to be experimentally implemented. One important goal is to increase the baseline distance between telescopes in interferometry, and thus improve the angular resolution of the celestial object. Some of the earlier proposals rely on the use of quantum repeaters to connect the two baseline stations. However, another proposal employs other quantum optical approaches to circumvent the need for quantum repeaters, while still providing a quantum advantage. I will discuss the on-going project for building quantum-enhanced telescopes for precision astrometry, i.e., measurements of position and velocity of celestial objects. I will present a proof-of-principle experimental demonstration of a two-photon interferometer for such goal. Moreover, I will present a single-photon-sensitive spectrometer, based on a linear array of 512 single-photon avalanche diode detectors, with 0.04 nm spectral and 40 ps temporal resolutions. This device enables us to implement a spectral binning technique, essentially allowing us to perform multiple measurements together, because each frequency can be treated as an independent measurement. Such device could also be used in other applications. Lastly, I will report on our frequency-resolved Hanbury Brown-Twiss experiments. Our work represents an important step towards quantum telescopes.
Observations using interferometers provide sensitivity to features of images on angular scales much smaller than any single telescope, on the order of Δθ ∼ λ/b where b is the interferometric baseline. Present-day optical interferometers are essentially classical, interfering single photons with themselves. However, there is a new wave of interest in interferometry using multiple photons, whose mechanisms are inherently quantum mechanical, which offer the prospects of increased baselines and finer resolutions among other advantages. We will discuss recent ideas and results for quantum-assisted interferometry using the resource of entangled pairs, and specifically a two-photon amplitude technique aimed at improved precision in astrometry.
High-angular-resolution imaging is crucial for many applications in modern astronomy and astrophysics. The fundamental diffraction limit constrains the resolving power of both ground-based and spaceborne telescopes. The recent idea of a quantum telescope based on the optical parametric amplification (OPA) of light aims to bypass this limit for the imaging of extended sources by an order of magnitude or more. We present an updated scheme of an OPA-based device and a more accurate model of the signal amplification by such a device. The semiclassical model that we present predicts that the noise in such a system will form so-called light speckles as a result of light interference in the optical path. Based on this model, we analysed the efficiency of OPA in increasing the angular resolution of the imaging of extended targets and the precise localization of a distant point source. According to our new model, OPA offers a gain in resolved imaging in comparison to classical optics. For a given time-span, we found that OPA can be more efficient in localizing a single distant point source than classical telescopes.
A quantum-enhanced telescope (interferometer) can have significant advantages in precisely measuring the angular position of remote objects through sending out ancillary quantum entanglement pairs alongside the large baselines of telescopes. In principle, the larger the baseline, the higher the expected measurement resolution. However, the well-known major problem of photon transmission loss would drastically undermine the practical application of all quantum-enhanced telescopes and optical interferometers that transmit photons along the baseline, especially for the large baselines required for high angular resolution. Here, we propose a photon-transmission-loss-independent quantum-enhanced interferometer that is robust to the transmission loss and keeps its advantages unchanged given whatever large baseline. This removes the well-known barrier to the practical application of quantum-enhanced telescopes. Moreover, in contrast to the previous results of quantum-entanglement-enhanced telescopes requesting sophisticated resources—perfect single-photon entanglement, photon-number-resolving detectors, or quantum memories—our method requires only threshold detectors and tunable coherent-state or two-mode squeezed-state sources, which are mature technologies nowadays, and it does not need any quantum memory. We demonstrate the high performance of our method using Fisher information. For the phase difference of weak light from a remote star, the high-quality result of Fisher information remains constant under arbitrarily large transmission loss, and hence all the advantageous results and the performance of our method are actually independent of transmission loss.
periodicity of phase readout introduces a wrap-around ambiguity, which confines the unambiguous measurement range to a single period and leads to a structural trade-off between precision and measurement range in high-sensitivity settings. To address this problem, we propose a robust Chinese remainder theorem-based multi-baseline measurement scheme: we choose a set of pairwise coprime scale factors and recover the wrap-around number from congruence relations among the reduced phases. In the setting of optical-interferometric quantum telescopes, we construct a telescope array based on the Chinese remainder theorem using fractional baselines, which substantially enlarges the unambiguous angular range (effective field of view) while retaining the high precision enabled by long baselines. Numerical simulations show that, under the same constraint on the shortest achievable baseline, our scheme achieves an exponential improvement in detection range over existing methods and attains a better range-precision trade-off with fewer probing resources. This framework supports practical multi-baseline quantum-interferometric observations and can be generalized to other phase-sensitive quantum precision-measurement tasks.