Criteria for optimal entanglement-assisted long baseline telescopy

Abstract

Entanglement-assisted telescopy protocols have been proposed as a means to extend the baseline of optical interferometric telescopes. However, the optimal entangled resource and a clear optimality criterion have remained unclear. Here, we propose a novel framework for systematically characterizing entanglement-assisted telescopy by integrating quantum metrology tools with the superselection rule (SSR) framework from quantum information theory. In our approach, the estimation problem in quantum telescopy is rigorously quantified using the quantum Fisher information (QFI) under SSR constraints. Building on this framework, we derive the fundamental limits of astronomical parameter estimation with finite entanglement resources and introduce new protocols that outperform previous methods and asymptotically saturate the optimal bound. Moreover, our proposed protocols are compatible with existing linear-optical technology and could inspire practical quantum telescopy schemes for near-term, lossy, and repeaterless quantum networks.

Figures (4)

• Figure 1: (a): Direct detection: light collected at two telescopes A and B is combined to interfere. (b): Entanglement-assisted protocol: shared quantum resources are provided to each telescope to enable interferometric imaging via local linear-optical circuit $\mathcal{U}$.
• Figure 2: The Quantum Fisher information (QFI) ratio $\mathbb{h}$ as a function of ancilla photon number $N$. Different entangled states are described in Table \ref{['tab: assisted scheme']}
• Figure 3: Schematic of near-deterministic teleportation: (1) Quantum Fourier transformation $\mathcal{F}_{N+1}$ is implemented at telescope A; (2) Measurement outcome $n$: number of photons detected, and $\vec{d}$: arrangement of detection are sent to telescope B for phase correction; (3) A scanning interferometric measurement is performed at telescope B.
• Figure 4: Schematic of near-deterministic teleportation: (1) Quantum Fourier transformation $\mathcal{F}_{N+1}$ is implemented at telescope A; (2) Measurement outcome $n$: number of photons detected, and $\vec{s}$ arrangement of detection is sent to telescope B for phase correction; (3) A scanning interferometric measurement is performed as in the direct interference scheme.

Theorems & Definitions (29)

• Theorem 1
• Lemma 1
• Lemma 2
• Definition 1
• Lemma 3
• Proposition 1
• Remark
• Theorem 2
• Remark
• Corollary 1