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arxiv: 2604.20353 · v1 · submitted 2026-04-22 · 🪐 quant-ph

Comment on "Quantum Limits to Incoherent Imaging are Achieved by Linear Interferometry"

George Brumpton , Aiman Khan , Helia Hooshmand , Samanta Piano , Gerardo Adesso This is my paper

Pith reviewed 2026-05-10 00:22 UTC · model grok-4.3

classification 🪐 quant-ph
keywords quantum imaginglinear interferometryquantum Fisher informationincoherent emittersquantum metrologyoptical resolution
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The pith

The linear interferometer proposed for incoherent imaging is flawed and suboptimal.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This comment identifies an error in the linear interferometer construction given in the supplemental material of a 2019 paper on quantum limits to imaging. The original design does not reach the best possible precision for resolving the positions of N weak incoherent emitters. The authors supply the corrected derivation of the optimal interferometer that saturates the quantum Fisher information bound. A reader would care because the result clarifies how linear optics can attain fundamental quantum limits in imaging without additional resources.

Core claim

We show that the construction of the linear interferometer in the Supplemental Material of arXiv:1909.09581 is flawed, leading to a generally suboptimal solution. We then provide the correct derivation of the optimal interferometric configuration that achieves the quantum Fisher information limit for imaging N weak incoherent emitters.

What carries the argument

The optimal linear interferometer configuration, obtained by deriving the arrangement of beam splitters and phase shifters that saturates the quantum Fisher information for the positions of N weak incoherent emitters.

If this is right

  • Claims that the 2019 construction achieves the quantum limit must be revised.
  • Linear interferometry can attain the ultimate precision for imaging weak incoherent sources when the phases and beam-splitter ratios are chosen correctly.
  • The corrected configuration supplies an explicit recipe for building an optimal imaging interferometer.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The result highlights that parameter optimization is essential to reach quantum bounds in optical metrology setups.
  • Experimental groups working on quantum-enhanced imaging may need to adjust their interferometer designs accordingly.
  • The approach could be extended to test whether similar corrections apply to other proposed linear-optical imaging schemes.

Load-bearing premise

The specific interferometer construction described in the 2019 supplemental material is the one its authors intended, and the new derivation reaches the quantum Fisher information bound without hidden assumptions on source statistics or detection efficiency.

What would settle it

Direct computation of the quantum Fisher information for the original versus the corrected interferometer with N=2 emitters would show whether only the corrected version saturates the bound.

Figures

Figures reproduced from arXiv: 2604.20353 by Aiman Khan, George Brumpton, Gerardo Adesso, Helia Hooshmand, Samanta Piano.

Figure 1
Figure 1. Figure 1: FIG. 1. Fisher information versus separation FIG. 1. Fisher information versus separation [PITH_FULL_IMAGE:figures/full_fig_p001_1.png] view at source ↗
read the original abstract

We show that the construction of the linear interferometer in the Supplemental Material of arXiv:1909.09581 is flawed, leading to a generally suboptimal solution. We then provide the correct derivation of the optimal interferometric configuration that achieves the quantum Fisher information limit for imaging N weak incoherent emitters.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

0 major / 2 minor

Summary. The manuscript claims that the construction of the linear interferometer in the Supplemental Material of arXiv:1909.09581 is flawed and leads to a generally suboptimal solution. It provides the correct derivation of the optimal interferometric configuration that achieves the quantum Fisher information limit for imaging N weak incoherent emitters.

Significance. If the analysis holds, this comment is significant because it corrects an error in a prior work on quantum limits to incoherent imaging, providing the proper optimal linear interferometry setup. This is important for advancing accurate theoretical models and experimental designs in quantum metrology. The paper offers a clear identification of the flaw and a new derivation without apparent internal inconsistencies.

minor comments (2)
  1. The abstract and introduction should explicitly state the arXiv number and title of the commented paper for immediate context.
  2. A brief discussion on the implications for experimental feasibility would enhance the paper's impact.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for their positive evaluation of our manuscript and for recommending acceptance. We are pleased that the significance of identifying the flaw in the prior construction and providing the correct optimal interferometric configuration has been recognized.

Circularity Check

0 steps flagged

No significant circularity detected

full rationale

The manuscript is a comment paper that critiques the linear interferometer construction in the supplemental material of an external cited work (arXiv:1909.09581) and supplies an independent derivation of the optimal interferometric configuration for saturating the quantum Fisher information bound on imaging N weak incoherent emitters. All load-bearing steps rely on standard quantum optics and parameter estimation formalism applied to the external setup, with no self-definitional reductions, no renaming of fitted quantities as predictions, and no load-bearing self-citations. The argument is therefore self-contained against external benchmarks and does not reduce any claimed result to its own inputs by construction.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Insufficient information; abstract alone does not disclose any free parameters, axioms, or invented entities.

pith-pipeline@v0.9.0 · 5344 in / 995 out tokens · 33799 ms · 2026-05-10T00:22:22.049540+00:00 · methodology

discussion (0)

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Reference graph

Works this paper leans on

3 extracted references · 3 canonical work pages · 1 internal anchor

  1. [2]

    M. G. A. Paris, Quantum estimation for quantum technology, In- ternational Journal of Quantum Information7, 125 (2009). FIG. 1. Fisher information versus separationθscaled byk/z 0, with sources atx=0 andx=θalong with collectors atu=0,1 (inset). Comparison between the quantum and classical curves shows subop- timality of the QR-based construction proposed ...

    work page 2009

  2. [3]

    C. Lupo, Z. Huang, and P. Kok, Quantum limits to incoherent imaging are achieved by linear interferometry, Physical Review Letters124, 080503 (2020)

    work page 2020

  3. [4]

    M. G. A. Paris, Quantum estimation for quantum technology, In- ternational Journal of Quantum Information7, 125 (2009). arXiv:2604.20353v1 [quant-ph] 22 Apr 2026

    work page internal anchor Pith review Pith/arXiv arXiv 2009