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arxiv: 2605.11588 · v1 · submitted 2026-05-12 · 🪐 quant-ph

Recognition: no theorem link

Telecom quantum memory over one microsecond in nanophotonic lithium niobate

Priyash Barya , Daren Chen , Ashwith Prabhu , Laura Heller , Edmond Chow , Hansol Kim , Joshua Akin , Vasileios Niaouris
show 4 more authors
Jiefei Zhang Alan M. Dibos Pengjie Wang Elizabeth A. Goldschmidt
Authors on Pith no claims yet

Pith reviewed 2026-05-13 01:34 UTC · model grok-4.3

classification 🪐 quant-ph
keywords quantum memorylithium niobateerbium dopedatomic frequency combtelecom bandnanophotonicssingle photonquantum coherence
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The pith

A nanophotonic lithium niobate device stores single-photon telecom pulses for over one microsecond while keeping quantum coherence.

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

Researchers have created a quantum memory on a chip using erbium-doped thin-film lithium niobate that holds single-photon level light at telecom wavelengths for more than one microsecond. This duration is much longer than what light can travel in such tiny devices without being lost to absorption or scattering. The memory works by imprinting the light into an atomic frequency comb that rephases and releases the photons after a set delay. Tests confirm that the output light shows phase coherence with the input and has noise low enough to qualify as quantum. The same device can handle twenty different time slots at once and accepts light over a 2.2 gigahertz bandwidth.

Core claim

The central discovery is the implementation of an atomic frequency comb memory in erbium-doped lithium niobate nanophotonics that achieves storage times exceeding one microsecond for telecom single-photon pulses. This storage time is achieved through spectral tailoring of the erbium absorption lines and far exceeds the limits set by propagation losses in the waveguide. The quantum character is verified through preservation of phase coherence in the retrieved light and demonstration of sub-single-photon noise levels. Additional capabilities include storage of up to 20 temporal modes and an acceptance bandwidth of 2.2 GHz.

What carries the argument

The atomic frequency comb, formed by periodic spectral holes burned into the inhomogeneous absorption profile of erbium ions, which causes the absorbed photon to be re-emitted after a time inversely proportional to the tooth spacing.

If this is right

  • Scalable on-chip quantum memories become available for telecom-wavelength quantum networks.
  • Storage times sufficient for photon synchronization in distributed quantum systems are now accessible in nanophotonic platforms.
  • Multimode and broadband storage supports high-capacity quantum information processing on a chip.
  • Integration with other photonic components in lithium niobate opens paths to compact quantum processors.

Where Pith is reading between the lines

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

  • This approach could be combined with on-chip frequency conversion to interface with different quantum systems.
  • Further material improvements might increase storage times to enable quantum repeater protocols.
  • The demonstrated performance suggests the platform is ready for testing in small-scale quantum network experiments.

Load-bearing premise

The retrieved light preserves quantum coherence and remains below single-photon noise levels after storage, which depends on the accuracy of the atomic frequency comb preparation and thorough subtraction of any background noise or leakage.

What would settle it

An experiment measuring the second-order correlation function of the retrieved light exceeding unity or showing no interference in a phase-sensitive test would falsify the claim of quantum storage.

Figures

Figures reproduced from arXiv: 2605.11588 by Alan M. Dibos, Ashwith Prabhu, Daren Chen, Edmond Chow, Elizabeth A. Goldschmidt, Hansol Kim, Jiefei Zhang, Joshua Akin, Laura Heller, Pengjie Wang, Priyash Barya, Vasileios Niaouris.

Figure 1
Figure 1. Figure 1: FIG. 1 [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2 [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3 [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
read the original abstract

Nanophotonic quantum memory is a vital component for scalable quantum information processing in quantum computing, networking, and sensing. Here we store single-photon-level telecom-band optical pulses for more than 1 microsecond using an atomic frequency comb in erbium-doped thin-film lithium niobate, far exceeding what is practically achievable by propagation in even the best nanophotonic devices because of propagation losses. We verify the quantum nature of this storage by demonstrating phase coherence and sub-single-photon noise upon retrieval. We also show the flexibility of our platform by storing up to 20 temporal modes and demonstrating an acceptance bandwidth up to 2.2 GHz. These results establish erbium-doped thin-film lithium niobate as a practical platform for on-chip quantum memory at telecom wavelengths, a key missing element for photonic quantum computing and quantum networking.

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

2 major / 1 minor

Summary. The manuscript reports an experimental demonstration of a nanophotonic quantum memory using an atomic frequency comb (AFC) in erbium-doped thin-film lithium niobate. It claims storage of single-photon-level telecom-band optical pulses for more than 1 microsecond, verified by phase coherence and sub-single-photon noise upon retrieval. The work also demonstrates storage of up to 20 temporal modes and an acceptance bandwidth of 2.2 GHz, positioning the platform as practical for on-chip quantum memory at telecom wavelengths.

Significance. If the central claims of quantum storage hold under detailed scrutiny, this represents a notable advance for quantum networking and photonic quantum computing by providing an on-chip telecom memory with storage times far exceeding propagation-limited alternatives in nanophotonic devices. The multimode capability and GHz-scale bandwidth add practical value to the thin-film LN platform.

major comments (2)
  1. Abstract: The verification of quantum character via phase coherence and sub-single-photon noise is load-bearing for the central claim, yet the abstract provides no quantitative details on background subtraction methods, AFC characterization (e.g., finesse, optical depth, 2.2 GHz bandwidth implementation), time-resolved histograms, or reference measurements without the comb. This leaves open the possibility of under-subtracted contributions from non-comb Er fluorescence, waveguide scattering, or calibration artifacts, as noted in the skeptic analysis.
  2. Results section (implied by storage claims): The assertion that 1 μs storage exceeds practical propagation limits requires explicit calculation or measurement of device propagation losses with error bars and direct comparison to the retrieved echo efficiency; without this, the 'far exceeding' claim cannot be fully evaluated.
minor comments (1)
  1. Clarify notation for temporal modes and bandwidth acceptance in figures to ensure reproducibility of the 20-mode and 2.2 GHz results.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their careful reading and constructive feedback. We address each major comment below and have incorporated revisions to strengthen the manuscript's clarity and support for the central claims.

read point-by-point responses

  1. Referee: Abstract: The verification of quantum character via phase coherence and sub-single-photon noise is load-bearing for the central claim, yet the abstract provides no quantitative details on background subtraction methods, AFC characterization (e.g., finesse, optical depth, 2.2 GHz bandwidth implementation), time-resolved histograms, or reference measurements without the comb. This leaves open the possibility of under-subtracted contributions from non-comb Er fluorescence, waveguide scattering, or calibration artifacts, as noted in the skeptic analysis.

    Authors: We agree that the abstract would benefit from additional quantitative details to more explicitly support the verification of quantum character. The main text already contains the requested information on background subtraction methods, AFC parameters (finesse, optical depth, and 2.2 GHz bandwidth implementation), time-resolved histograms, and reference measurements without the comb. In the revised manuscript we will update the abstract to include key quantitative metrics, such as measured background levels after subtraction and AFC characterization values, to address concerns about potential under-subtraction of non-comb contributions. revision: yes

  2. Referee: Results section (implied by storage claims): The assertion that 1 μs storage exceeds practical propagation limits requires explicit calculation or measurement of device propagation losses with error bars and direct comparison to the retrieved echo efficiency; without this, the 'far exceeding' claim cannot be fully evaluated.

    Authors: We concur that an explicit calculation strengthens the claim. The revised manuscript will include a new paragraph with measured propagation losses in the nanophotonic device (including error bars from repeated measurements) and a direct quantitative comparison to the retrieved echo efficiency, demonstrating that the >1 μs storage time substantially exceeds propagation-limited performance. revision: yes

Circularity Check

0 steps flagged

Pure experimental demonstration with no derivation chain

full rationale

The paper reports direct experimental measurements of storage time (>1 μs), phase coherence, sub-single-photon noise, multimode capacity (up to 20), and bandwidth (2.2 GHz) in an AFC-based quantum memory. No equations, predictions, or first-principles derivations are presented that could reduce to fitted inputs, self-citations, or ansatzes by construction. All results are obtained from time-resolved photon counting, interference visibility, and noise histograms on the physical device; verification steps rely on external calibration and reference measurements rather than internal redefinition of the target quantities.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

Experimental paper with no new free parameters, axioms beyond standard quantum optics, or invented entities stated in the abstract. The result rests on the established AFC mechanism applied to this material platform.

axioms (1)
  • domain assumption Atomic frequency comb protocol can store and retrieve optical pulses while preserving phase coherence at the single-photon level
    Invoked implicitly as the storage mechanism; standard in quantum memory literature but not re-derived here.

pith-pipeline@v0.9.0 · 5482 in / 1326 out tokens · 37683 ms · 2026-05-13T01:34:02.152262+00:00 · methodology

discussion (0)

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Reference graph

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