Pith. sign in

REVIEW 4 major objections 6 minor 32 references

ND1 centers in diamond for long-term data storage in extreme conditions

T0 review · 4 major / 6 minor · reviewed 2026-08-06 · deepseek-v4-flash

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗ Review JSON

Pith's one-line read A 1030 nm femtosecond laser writes sub-micron ND1 defect pits in diamond whose UV photoluminescence survives acids, 4–500 K, and 5 T fields, making a write-once 3D archival medium.

desk verdict A real writing/reading demonstration of ND1 pits in diamond, but the million-year and 500 Mbit/s headline numbers are extrapolations, not measurements. read the letter →

arxiv 2507.11363 v1 pith:FYSBZLVH submitted 2025-07-15 physics.optics

Ahsan Ali , Wei Huang , Khadga Jung Karki This is my paper · ORCID
classification physics.optics
keywords ND1centersdiamondopticaldatastoragefemtosecondlaserwritingthree-photonabsorptionphotoluminescenceextremeconditionswrite-oncememory
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

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

The reading

This paper reports a way to store data inside a diamond as tiny luminous defects called ND1 centers. Focusing 1030 nm femtosecond laser pulses at a chosen spot writes a sub-micron "pit" rich in ND1 centers, on the surface or in the bulk, and the same laser at lower power reads the pit back through blue-violet photoluminescence excited by three-photon absorption. The authors argue this gives a write-once, three-dimensional optical storage medium that needs no confocal microscope, is readable at up to 500 Mbit/s, and survives conditions—temperatures from 4 K to 500 K, 5 T magnetic fields, and strong acids—under which other diamond color-center memories fade. If correct, it offers an archival medium for irreplaceable data in harsh environments, with the authors projecting stability over millions of years.

What carries the argument

The central object is the ND1 center, a negatively charged single vacancy in the diamond lattice whose photoluminescence lies in the UV/violet region, peaking around 400 nm. The writing mechanism is multiphoton absorption plus avalanche ionization from tightly focused femtosecond pulses: the band gap requires at least five photons for bulk ionization, but once a pit starts, lower energies grow it. The reading mechanism is three-photon absorption at 1030 nm, resonant with the center's 3.2–3.6 eV transitions and non-resonant with NV and GR1 emissions, so ND1 dominates the collected light; because 3PA is confined to the focal volume, depth-resolved readout works without confocal gating. The less than 2 ns photoluminescence lifetime is the quantity that sets the 500 Mbit/s read-speed ceiling.

What would settle it

Measure the PL intensity of written ND1 pits as a function of time at several elevated temperatures, for example 300–700 K, and fit an Arrhenius decay law; if the extrapolated decay constant at storage temperature predicts measurable loss within hundreds of years, or if annealing at a few hundred kelvin for weeks reduces the UV photoluminescence, the million-year claim is wrong. Alternatively, repeated read cycles at the claimed 500 Mbit/s scanning conditions could show photobleaching or pit growth that would falsify the no-degradation claim.

Watch

Extended reading notes

Core claim

Sub-micron-sized spots with a high density of ND1 centers—negatively charged single vacancies in diamond—can be created deterministically at chosen surface and interior locations by focusing near-infrared femtosecond pulses (1030 nm) into an undoped diamond. Reading uses the same wavelength at lower pulse energy; the ND1 emission peaks below 400 nm and is driven by three-photon absorption (3PA), which confines excitation to the focal volume and eliminates the need for confocal microscopy. The emission has a mean lifetime under 2 ns, setting a read limit near 500 Mbit/s, and remains stable after 180 minutes of continuous exposure, repeated measurements over a year, treatment with aqua regia and piranha solution, magnetic fields up to 5 T, and temperatures from 4 K to 500 K. The paper concludes that ND1-based pits form a write-once, high-density, three-dimensional optical data storage medium compatible with existing Blu-ray-era infrastructure and capable, by the authors' extrapolation, of preserving data for millions of years.

Load-bearing premise

The million-year claim rests on assuming that the ND1 photoluminescence stability observed over one year and after short exposures to 4–500 K, 5 T, and acids extrapolates to geological timescales, with no slow migration of vacancies or change of charge state; the paper offers no kinetic model or accelerated-aging data for that extrapolation.

Editorial extensions

If this is right

  • Data can be written and read with the same 1030 nm femtosecond laser, so the read/write head is simpler than the two-wavelength confocal system used for GR1-center diamond storage.
  • Because read excitation is three-photon confined to the focal volume, multilayer readout is possible without confocal microscopy, and the UV emission wavelength gives diffraction-limited resolution better than visible or near-infrared readout.
  • With a 2 ns PL lifetime, sequential read speed is limited to about 500 Mbit/s, comfortably above Blu-ray's 36 Mbit/s; a 1.83 GHz Yb-fiber laser with more than 50 nJ pulses puts write speed above 200 MByte/s, subject to mechanical scanning.
  • The written pits are write-once: they cannot be erased under normal conditions, making the medium suited to long-term archival rather than rewritable storage.
  • The demonstrated stability under 4–500 K, 5 T fields, and aggressive acids means storage media could be deployed in extreme environments—reactors, space, high-radiation or corrosive settings—where conventional discs and solid-state drives fail.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • If the million-year extrapolation holds, the practical bottleneck shifts from media lifetime to reader/writer mechanics and laser cost; on-chip femtosecond amplification could make such archival drives portable.
  • The same three-photon writing scheme might be extendable to other wide-bandgap crystals or to doped diamond, where lower writing thresholds and smaller pits could push areal density toward Blu-ray dimensions and capacities rivaling solid-state drives.
  • A testable near-term extension is to write adjacent pits at varying pulse energies and read them repeatedly to map error rate and crosstalk as a function of layer spacing, something the present demonstration only qualitatively establishes.
  • The paper's stability tests are short-duration; a natural follow-up is accelerated aging via sustained high-temperature storage or repeated thermal cycling to convert the million-year conjecture into a measured activation energy.
Share X Bluesky LinkedIn Reddit HN

Signed reviews

No signed human review yet.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

4 major / 6 minor

Summary. The paper reports femtosecond-laser writing of sub-micron luminescent pits in diamond that emit in the UV, attributes the emission to ND1 (negatively charged single vacancy) centers, and demonstrates readout from four layers. The authors characterize the excitation as three-photon absorption, measure a PL lifetime below 2 ns, and report stability over one year and after exposure to acids, a 5 T magnetic field, and temperatures from 4 K to 500 K. They argue that this enables high-density three-dimensional optical data storage with a read speed of 500 Mbit/s and a lifetime extending to millions of years.

Significance. If the durability and capacity claims were properly supported, this would be a valuable addition to optical archival storage, because writing and reading with a single 1030 nm source and epi-detection would simplify the instrumentation needed for GR1-based diamond storage. Strengths include deterministic creation with a commercial femtosecond laser, a plausible three-photon absorption mechanism supported by intensity-dependence and phase-modulation measurements, and explicit chemical, magnetic, and thermal stress tests with no observed degradation. The main limitations are that the million-year stability is an extrapolation without a kinetic model, and the capacity and read-speed claims are theoretical or unquantified, so the demonstrated advance is more modest than the abstract suggests.

major comments (4)
  1. [Discussion / Stability of the emission] The claim that stored data survive for millions of years (Abstract and the final Discussion paragraph) is not supported by the presented observations. The evidence is one year of PL stability at room temperature plus short exposures to 4-500 K, a 5 T field, and acids. No kinetic model, Arrhenius parameters, or accelerated-aging data are provided, and the analogy to GR1 (ref 20) is imperfect because ND1 is the negatively charged single vacancy: the negative charge state can be lost by thermal or optical ionization or by electron capture at other defects, converting ND1 to GR1 and extinguishing the 400 nm PL. A process with an activation energy of order 1 eV would be invisible in a one-year test but could erase data on much shorter timescales. This is a load-bearing extrapolation, not a demonstrated property.
  2. [Results / Writing and reading / Fig. 1(D)] No volumetric storage density, interlayer spacing, bit pitch, or bit error rate is measured or reported. The four-layer demonstration in Fig. 1(D) establishes multilevel writing, and the statement that 'no interlayer crosstalk is observed' is not accompanied by a quantitative signal-to-background or crosstalk metric. The abstract's 'high-density, three-dimensional' claim and the Discussion's comparison with other 3D ODS systems are therefore not quantified. Please provide measured layer spacing, areal or volumetric density, and readout error statistics, or temper the capacity claims accordingly.
  3. [Results / Read speed / Fig. 3(C)] The 500 Mbit/s read speed is presented as a demonstrated performance (Abstract, Results, Discussion), but it is only a lifetime-limited upper bound: no readout rate is measured, and the actual raster-scanning readout with a nanopositioning stage will be far slower. Moreover, a PL lifetime of 2 ns does not by itself set a sequential bit rate of 500 Mbit/s unless bits are temporally spaced by at least a few lifetimes to avoid inter-bit interference, and the integration time needed for adequate signal-to-noise is not addressed. Please distinguish a theoretical ceiling from demonstrated throughput.
  4. [Fig. 3(C) and text on PL lifetime] The text states that the average PL lifetime is below 2 ns and that this gives a 500 Mbit/s limit, while the Fig. 3(C) caption reports a bi-exponential decay with lifetimes shorter than 10 ns. These statements are not obviously consistent. Please report the fitted lifetime components and their amplitudes, and explain how the 2 ns average is obtained and how the decay tail affects sequential readout.
minor comments (6)
  1. [Throughout] The unit 'MBits/s' should be written as 'Mbit/s' or 'Mb/s' to avoid confusion with megabytes per second; the paper already uses 'MByte/s' for write speed, so the distinction matters.
  2. [Results / Stability] The word 'accessed' in 'photo-stability ... is accessed' and 'stabilities have been accessed' should be 'assessed'.
  3. [Fig. 1 and Fig. 4 captions] 'Dichoric mirror' should be 'dichroic mirror'.
  4. [Affiliation] The affiliation of the second author contains a typo: 'Techion' should be 'Technion'.
  5. [Fig. 2] The sentence 'in greater detail (Fig. 2(A).' has an unbalanced parenthesis; it should read '(Fig. 2(A))'.
  6. [Experimental setups] The section heading 'Measurement of PL liftime' contains a typo; it should be 'Measurement of PL lifetime'.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: the core claims are anchored to an external spectral reference and direct in-paper measurements; the million-year durability statement is an extrapolation but not a circular derivation.

full rationale

The paper's derivation chain is empirical and self-contained. The identification of the emissive pits as ND1 centers rests on an external spectral reference (ref 24), not on the paper's own conclusions. The three-photon absorption order is established by two independent in-paper measurements—harmonic distortions at 4 and 6 kHz in the phase-modulation experiment and a cubic power dependence—together with the 3.2-3.6 eV resonance from ref 24. The 500 Mbit/s read-speed limit is a straightforward arithmetic consequence of the measured 2 ns photoluminescence lifetime. The stability claims are direct observations over one year and after thermal, magnetic, and chemical exposures. Refs 25-27, including the authors' prior phase-modulation method papers, are cited as a measurement technique rather than as the source of the target result, so they are not load-bearing. The Discussion's 'extending to millions of years' statement is an extrapolation from a one-year stability observation and an analogy to GR1 centers (ref 20), lacking a kinetic model or accelerated-aging data; this is a support gap and a correctness risk, but it is not circular because the claim is not derived by construction from the measured data. No fitted parameter is renamed as a prediction, and no uniqueness theorem or ansatz is imported via self-citation. Therefore the paper does not exhibit circular reasoning.

Assumptions & free parameters 0 free parameters · 4 assumptions · 0 invented entities

The paper introduces no fitted parameters and no new postulated entities; the ND1 center is a previously characterized defect. The central claims rest on literature-based defect identification, standard multiphoton nonlinear optics, and an extrapolation of short-term stability to geological timescales.

assumptions (4)
  • domain assumption The sub-400 nm PL band is specifically assigned to ND1 centers.
    Relies on ref 24 and the 3PA resonance argument in the Results section; the paper does not confirm the defect identity with low-temperature ZPL, absorption, or control measurements.
  • standard math PL harmonic distortion at 4 and 6 kHz under 2 kHz intensity modulation implies three-photon absorption.
    Standard nonlinear optics relation between nth-order intensity response and harmonic content; used to infer 3PA in Fig. 3(A).
  • domain assumption Short-term stability (one year, 4-500 K, 5 T, acids) implies stability over millions of years.
    No kinetic model or accelerated-aging data is provided; the million-year claim in the Discussion is extrapolated from short-term tests and prior GR1 work (ref 20).
  • domain assumption Readout of four stacked layers shows no interlayer crosstalk.
    Based on visual inspection of Fig. 1(D); no quantitative crosstalk, signal-to-noise, or bit-error analysis is presented.

how reviews work

0 comments
Cite this review

Pith. "Pith review of ND1 centers in diamond for long-term data storage in extreme conditions." pith.science (2026). https://pith.science/paper/FYSBZLVH

@misc{pith2026250711363,
  author       = {Pith},
  title        = {Pith review of: ND1 centers in diamond for long-term data storage in extreme conditions},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/FYSBZLVH}},
  note         = {Machine review of arXiv:2507.11363}
}
read the original abstract

Practically feasible long-term data storage under extreme conditions is an unsolved problem in modern data storage systems. This study introduces a novel approach using ND1 centers in diamonds for high-density, three-dimensional optical data storage. By employing near-infrared femtosecond laser pulses, we demonstrate the creation of sub-micron ND1 defect sites with precise spatial control, enabling efficient data encoding as luminescent ''pits." The ND1 centers exhibit robust photoluminescence in the UV spectrum, driven by three-photon absorption, which intrinsically provides a 3D reading of the data. Remarkably, these centers remain stable under extreme electric and magnetic fields, temperatures ranging from 4 K to 500 K, and corrosive chemical environments, with no degradation observed over extended periods. A reading speed of 500 MBits/s, limited by the lifetime of the photoluminescence, surpasses conventional Blu-ray technology while maintaining compatibility with existing optical data storage infrastructure. Our findings highlight diamond-based ND1 centers as a promising medium for durable, high-capacity data storage, capable of preserving critical information for millions of years, even under harsh conditions.

Discussion (0). Continue with ORCID to comment.

Reference graph

Works this paper leans on

32 extracted references · 31 canonical work pages

  1. [1]

    M. Gu, X. Li, Y. Cao, Optical storage arrays: a perspective for future big data storage. Light Sci. Appl. 3 (5), e177–e177 (2014)

    work page 2014

  2. [2]

    Trelles, P

    O. Trelles, P. Prins, M. Snir, R. C. Jansen, Big data, but are we ready? Nat. Rev. Genet. 12 (3), 224 (2011)

    work page 2011

  3. [3]

    Lambert, et al

    C.-H. Lambert, et al. , All-optical control of ferromagnetic thin films and nanostructures. Science 345 (6202), 1337–1340 (2014)

    work page 2014

  4. [4]

    M. Gu, Q. Zhang, S. Lamon, Nanomaterials for optical data storage. Nat. Rev. Mater. 1 (12) (2016)

    work page 2016

  5. [5]

    Zijlstra, J

    P. Zijlstra, J. W. M. Chon, M. Gu, Five-dimensional optical recording mediated by surface plasmons in gold nanorods. Nature 459 (7245), 410–413 (2009)

    work page 2009

  6. [6]

    Lu, et al

    Y. Lu, et al. , Tunable lifetime multiplexing using luminescent nanocrystals. Nat. Photonics 8 (1), 32–36 (2014)

    work page 2014

  7. [7]

    Ouyang, et al

    X. Ouyang, et al. , Synthetic helical dichroism for six-dimensional optical orbital angular momentum multiplexing. Nat. Photonics 15 (12), 901–907 (2021)

    work page 2021

  8. [8]

    Xiong, et al., Breaking the limitation of polarization multiplexing in optical metasurfaces with engineered noise

    B. Xiong, et al., Breaking the limitation of polarization multiplexing in optical metasurfaces with engineered noise. Science 379 (6629), 294–299 (2023)

    work page 2023

Show all 32 references
  1. [9]

    Meijer, et al

    J. Meijer, et al. , Generation of single color centers by focused nitrogen implantation. Appl. Phys. Lett. 87 (26), 261909 (2005), doi:10.1063/1.2103389, https://doi.org/10.1063/ 1.2103389

    2005 doi

  2. [10]

    Martin, R

    J. Martin, R. Wannemacher, J. Teichert, L. Bischoff, B. K ¨ohler, Generation and detection of fluorescent color centers in diamond with submicron resolution. Appl. Phys. Lett. 75 (20), 3096–3098 (1999)

    1999

  3. [11]

    Aharonovich, et al., Diamond-based single-photon emitters.Rep

    I. Aharonovich, et al., Diamond-based single-photon emitters.Rep. Prog. Phys. 74 (7), 076501 (2011). 14

    2011

  4. [12]

    Rothschild, C

    M. Rothschild, C. Arnone, D. J. Ehrlich, Excimer-laser etching of diamond and hard carbon films by direct writing and optical projection. Journal of Vacuum Science & Technology B: Microelectronics Processing and Phenomena 4 (1), 310–314 (1986), doi:10.1116/1.583320, https://do...

    1986 doi

  5. [13]

    Liu, et al

    Y. Liu, et al. , Fabrication of nitrogen vacancy color centers by femtosecond pulse laser il- lumination. Opt. Express 21 (10), 12843–12848 (2013), doi:10.1364/OE.21.012843, https: //opg.optica.org/oe/abstract.cfm?URI=oe-21-10-12843

    2013 doi

  6. [14]

    S. M. Pimenov, A. A. Khomich, B. Neuenschwander, B. J ¨aggi, V. Romano, Picosecond-laser bulk modification induced enhancement of nitrogen-vacancy luminescence in diamond.J. Opt. Soc. Am. B33 (3), B49–B55 (2016), doi:10.1364/JOSAB.33.000B49,https://opg.optica. org/josab/abstra...

    2016 doi

  7. [15]

    Chen, et al., Laser writing of coherent colour centres in diamond

    Y.-C. Chen, et al., Laser writing of coherent colour centres in diamond. Nat. Photonics 11 (2), 77–80 (2017)

    2017

  8. [16]

    Chen, et al., Laser writing of individual nitrogen-vacancy defects in diamond with near- unity yield

    Y.-C. Chen, et al., Laser writing of individual nitrogen-vacancy defects in diamond with near- unity yield. Optica 6 (5), 662–667 (2019), doi:10.1364/OPTICA.6.000662, https://opg. optica.org/optica/abstract.cfm?URI=optica-6-5-662

    2019 doi

  9. [17]

    Aslam, G

    N. Aslam, G. Waldherr, P. Neumann, F. Jelezko, J. Wrachtrup, Photo-induced ionization dynamics of the nitrogen vacancy defect in diamond investigated by single-shot charge state detection. New J. Phys. 15 (1), 013064 (2013), doi:10.1088/1367-2630/15/1/013064, https: //dx.doi.o...

    2013 doi

  10. [18]

    Dhomkar, J

    S. Dhomkar, J. Henshaw, H. Jayakumar, C. A. Meriles, Long-term data storage in diamond. Sci. Adv. 2 (10), e1600911 (2016), doi:10.1126/sciadv.1600911, https://www.science. org/doi/abs/10.1126/sciadv.1600911

    2016 doi

  11. [19]

    Monge, T

    R. Monge, T. Delord, C. A. Meriles, Reversible optical data storage below the diffraction limit. Nat. Nanotechnol. 19 (2), 202–207 (2024)

    2024

  12. [20]

    Zhou, et al., Terabit-scale high-fidelity diamond data storage.Nat

    J. Zhou, et al., Terabit-scale high-fidelity diamond data storage.Nat. Photonics 18 (12), 1327– 1334 (2024). 15

    2024

  13. [21]

    Zhao, et al., A 3D nanoscale optical disk memory with petabit capacity.Nature 626 (8000), 772–778 (2024)

    M. Zhao, et al., A 3D nanoscale optical disk memory with petabit capacity.Nature 626 (8000), 772–778 (2024)

    2024

  14. [22]

    P. S. Salter, et al. , Laser engineering nanocarbon phases within Diamond for science and electronics. ACS Nano 18 (4), 2861–2871 (2024)

    2024

  15. [23]

    K. K. Ashikkalieva, Laser-induced graphitization of Diamond bulk: The state of the art (A review). Phys. Wave Phenom. 30 (1), 1–16 (2022)

    2022

  16. [24]

    N. M. Kazuchits, et al., Luminescence of negatively charged single vacancies in diamond: ND1 center. Diam. Relat. Mater. 121 (108741), 108741 (2022)

    2022

  17. [25]

    K. J. Karki, L. Kringle, A. H. Marcus, T. Pullerits, Phase-synchronous detection of coherent and incoherent nonlinear signals. J. Opt. 18 (1), 015504 (2016)

    2016

  18. [26]

    Wang, et al., in operando quantification of single and multiphoton photocurrents in GaP and InGaN photodetectors with phase-modulated femtosecond light pulses.ACS Photonics (2023)

    C. Wang, et al., in operando quantification of single and multiphoton photocurrents in GaP and InGaN photodetectors with phase-modulated femtosecond light pulses.ACS Photonics (2023)

    2023

  19. [27]

    A. Ali, C. Wang, J. Cai, K. J. Karki, Probing silicon carbide with phase-modulated femtosecond laser pulses: Insights into multiphoton photocurrent.ACS Photonics 11 (4), 1502–1507 (2024)

    2024

  20. [28]

    Wang, et al

    C. Wang, et al. , Effects of impurity band on multiphoton photocurrent in GaN and InGaN photodetectors. Opt. Mater. (Amst.) 149 (114986), 114986 (2024)

    2024

  21. [29]

    Park, et al., High Power 1.83 GHz Femtosecond Yb-doped Fiber Laser Incorporating Repetition Rate Multipliers. Curr. Opt. Photonics 7 (6), 732–737 (2023)

    2023

  22. [30]

    T. J. Kippenberg, A. L. Gaeta, M. Lipson, M. L. Gorodetsky, Dissipative Kerr solitons in optical microresonators. Science 361 (6402), eaan8083 (2018)

    2018

  23. [31]

    Guo, et al., Ultrafast mode-locked laser in nanophotonic lithium niobate.Science 382 (6671), 708–713 (2023)

    Q. Guo, et al., Ultrafast mode-locked laser in nanophotonic lithium niobate.Science 382 (6671), 708–713 (2023)

    2023

  24. [32]

    M. A. Gaafar, et al., Femtosecond pulse amplification on a chip. Nat. Commun. 15 (1), 8109 (2024). 16 Acknowledgments The authors thank Prof. Elissaios Stavrou of Guangdong Technion-Israel Institute of Technology for providing a diamond crystal as a sample. Funding: KJK acknow...

    2024

Pith tools

Reviewed August 6, 2026 · model on record in the stance chip above.