REVIEW 3 major objections 4 minor 41 references
Introducing the Quantum Economic Advantage Online Calculator
T0 review · 3 major / 4 minor · reviewed 2026-08-05 · deepseek-v4-flash
Pith's one-line read The paper introduces an open-access online calculator that predicts when quantum computers will outperform cost-equivalent classical ones for a given problem, finding RSA-2048 break years around 2028–2034 and highly sensitive dates for Grov
desk verdict Useful tool paper with a reproducible numerical bug: the hardware slowdown numbers are 100x off from the stated formula, so Table III years should not be taken at face value. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The central object is the QEA point, defined by the equation Feas(t) = Adv(t), where Feas(t) converts physical qubits into a maximum solvable problem size via the physical-to-logical qubit ratio, and Adv(t) is the smallest problem size n satisfying C(n, 10^p (1+CIR)^Δt) = 10^{hws} (1+QIR)^Δt × Q(n) × P(QPS^{-1}(n)). The calculator draws these lines dynamically from user-editable roadmaps and runtime expressions; the robustness contrast between Shor and Grover emerges from how fast each side of the equation moves as parameters change.
What would settle it
Recompute the paper's predictions with measured values for the cost-equivalent classical processor count and the annual improvement rates of quantum hardware slowdown, error-correction overhead, and relative cost. The paper's own sensitivity charts show factor-of-ten changes shifting Grover's date by decades while Shor's date barely moves; tracking actual vendor qubit counts against the extrapolated roadmaps would also falsify specific years such as the RSA-2048 dates.
Extended reading notes
Core claim
The calculator operationalizes quantum economic advantage (QEA) as the intersection of two curves: a feasibility line giving the largest problem size a vendor's qubit roadmap can handle after error-correction overhead, and an advantage line giving the smallest problem size at which a cost-equivalent classical machine is slower. It extends an earlier framework with three new inputs—classical parallelizability, a qubit-connectivity penalty, and a cost-improvement rate—and solves for the year t* where the curves cross. Applying the tool to Shor's algorithm and Grover's search on superconducting, trapped-ion, and neutral-atom roadmaps yields QEA years of 2025–2032, RSA-2048 break years of 2028–2
Load-bearing premise
The load-bearing premise is that a cost-equivalent classical machine has 10^8 processors and that quantum slowdown, physical-to-logical qubit ratio, and relative costs improve at the assumed annual rates (10%, 23%, 10%); those values are hand-set, not measured, and every predicted year is scaled by them.
Editorial extensions
If this is right
- If the model is right, RSA-2048 becomes cryptographically vulnerable in the early-to-mid 2030s on at least one vendor roadmap, making migration of public-key infrastructure urgent.
- For exponential-advantage algorithms such as Shor's, qubit count and the physical-to-logical qubit ratio are the levers that move advantage dates; speed and cost parameters matter little.
- For quadratic-advantage algorithms such as Grover's, quantum gate speed and the cost of classical processors dominate; a machine with many slow qubits may never reach advantage for search-sized problems.
- Because the calculator is open and parameterized, competing forecasts can be traced to the specific assumptions that produce them, making disagreements about quantum timelines inspectable.
- The tool's 'no advantage by year 3000' output is a concrete consequence: under some parameter sets, certain problems will never become quantum-economically advantageous.
Reading between the lines
- The authors leave implicit that the hand-set values—10^8 cost-equivalent processors and 10% annual improvement rates—make the absolute years illustrative, not predictive; the transferable insight is the robustness ordering, not the calendar.
- A testable extension is to run the same calculator on other polynomial-speedup algorithms such as quantum simulation or optimization heuristics: the model predicts they should behave like Grover, not Shor.
- The connectivity penalty of √q can be calibrated empirically by compiling the same circuit for all-to-all and 2D architectures; if real overhead differs, QEA dates for different hardware types would need adjustment.
- The paper's feasibility-limited versus speed-limited distinction suggests a hardware-roadmap principle: focus on qubit scaling for exponential speedups and on gate speed for polynomial speedups.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper introduces an open-access web calculator that operationalizes the Choi-Moses-Thompson “Quantum Tortoise and Classical Hare” framework for quantum economic advantage (QEA). The tool takes as inputs algorithm runtimes, qubit roadmaps, error-correction ratios, hardware slowdowns, connectivity penalties, and improvement rates, and outputs the minimum advantage problem size n* and the year t* at which a given problem becomes both feasible and faster on quantum hardware. The authors analyze Shor factorization and Grover search on IBM, IonQ, and QuEra roadmaps, predicting QEA years and RSA-2048 break years (e.g., IBM 2034, IonQ 2033, QuEra 2028), and report a robustness analysis concluding that Shor-2048 predictions are more robust while Grover-based advantage is highly contingent on hardware speed and improvement assumptions.
Significance. If the implementation is faithful to its stated formulas, the calculator is a genuinely useful interactive instrument for comparative scenario analysis. Its strengths are transparency of the core equations, explicit modeling of parallelizability, connectivity penalties, and cost-equivalent processors, and a sensitivity analysis that exposes which parameters drive the predictions. The mathematical core is elementary and internally consistent. The qualitative contrast between Shor and Grover is, however, largely a formal consequence of the exponential-versus-quadratic speedup asymmetry in the runtime-equality equation, so the paper’s main analytic finding is more a property of the model than a new empirical discovery. Even so, making this structure visible to a broad audience is valuable. The central quantitative predictions are currently not reproducible from the stated inputs because of an undocumented factor of 100 in the hardware slowdown conversion, which is a load-bearing issue for Table III.
major comments (3)
- The hardware slowdown values in Table II are not derivable from the stated formula and default classical clock speed. With a 5 GHz classical clock (0.2 ns/operation), IBM's 12 ns 2-qubit gate gives a speed ratio of 60 (log10 ≈ 1.78), IonQ's 600,000 ns gate gives 3e6 (log10 ≈ 6.48), and QuEra's 250 ns gate gives 1250 (log10 ≈ 3.10). The reported slowdowns are 10^3.78, 10^8.48, and 10^5.1, each exactly 100 times larger. The text says these are 'converted using the formula from the inputs section,' but that formula does not include a 100x factor, and gate overhead is described separately as a user-input multiplicative factor. Because 10^hws enters the advantage condition Eq. (4) multiplicatively, all n* and t* values in Eqs. (5)-(6) scale with this missing factor; for Grover's quadratic speedup the implied shift in n* is quadratic in the slowdown, moving QEA years by decades. The paper must
- The qualitative robustness conclusion—Shor is feasibility-limited while Grover is speed-limited—is substantially entailed by the model before any parameter sweep. In Eq. (4), an exponential speedup makes n* depend logarithmically on 10^hws, whereas a quadratic speedup makes n* scale as (10^hws)^2. Thus the large sensitivity of Grover years to slowdown and the small sensitivity of Shor years to slowdown are formal consequences of the runtime-asymmetry structure, not emergent findings of the calculator. The paper should state this explicitly and reframe the result as a demonstration of the framework's analytic implications, rather than presenting it as an empirical discovery from the robustness plots.
- The specific year predictions in Table III rest on hand-set parameters—10^8 cost-equivalent processors, 10% QIR, 10% CIR, 23% RIR—whose values are acknowledged to be illustrative, with the processor count sourced to an unpublished working paper with overlapping authorship [35]. The paper's own robustness analysis (Figure 6) shows that factor-of-10 changes in these parameters shift Grover QEA years by decades. The limitations section acknowledges the rates are unknown, but the abstract and Table III present single-year predictions without this uncertainty. The manuscript should present Table III explicitly as a scenario-conditional output, not a point forecast, and should make the provenance of the 10^8 anchor auditable (e.g., by including the derivation in the paper or a supplement).
minor comments (4)
- The classical Shor/factoring runtime expression is typeset ambiguously as e(64/9 n)^{1/3}*(ln n)^{2/3}; the intended expression is exp((64/9)^{1/3} n^{1/3} (ln n)^{2/3}). Please correct the notation and state whether n refers to the integer to factor or its bit length, since the qubit-to-problem-size mapping depends on this.
- The sign convention for QIR, RIR, and CIR is confusing: the text says 'improvements are associated with negative values,' while Table II lists positive percentages with a note that the online tool uses negatives. The equations St+1 = St*(1+QIR/100) should be accompanied by an explicit statement that QIR is negative for improvement and by the domain of allowed values.
- The caps on hardware slowdown decay and the PLQR floor of 3 are mentioned in footnotes but are not represented in the equations in Section III-B. Please state these as piecewise constraints in the formal model so that the calculator's behavior is fully specified.
- The robustness figures are informative but their axes and the exact baseline value for each parameter are not described in the text. Adding a short caption or table listing the baseline values and the perturbation factors would make the sensitivity results reproducible by the reader.
Circularity Check
No circularity: the QEA calculator is a parameterized computation whose predictions follow from its stated equations and explicitly labeled assumptions.
full rationale
This paper is an implementation-and-extension paper, not a derivation of its framework from more basic principles. The QEA years in Table III are computed by solving the paper's stated equations (Adv(t)=Feas(t), Section III-B) from explicit inputs: classical/quantum runtimes, vendor roadmaps, PLQR, hardware slowdown, QIR, CIR, connectivity penalty, and processor count. None of these inputs is defined in terms of the output QEA years. The headline qualitative contrast (Shor robust, Grover contingent) is an analytic consequence of the asymptotic gap between exponential and quadratic speedups in the stated runtime-equality equation, and the paper itself explains this mechanism rather than treating it as an externally fitted result. The self-citations that are present ([3] framework by a co-author, [35] for the 10^8 processor assumption) supply modeling assumptions and parameter values, not theorems whose conclusions are presupposed. The paper explicitly labels trend rates and processor counts as 'reasonable and illustrative' and includes a sensitivity analysis (Section V-A) and limitations section acknowledging these unknowns. The apparent ~100x mismatch between the stated 5 GHz/12 ns speed-ratio formula and the reported 10^3.78 hardware slowdown is an arithmetic/reproducibility concern and possibly an unstated input assumption, but it is not a case of an output being equivalent to an input by construction, so it does not constitute circularity.
Assumptions & free parameters
free parameters (8)
- Quantum Improvement Rate (QIR) =
-10%/yr for all hardware
- Cost Improvement Rate (CIR) =
-10%/yr for all hardware
- Physical-Logical Qubit Ratio Improvement Rate (RIR) =
23%/yr for all hardware
- Baseline PLQR values =
IBM 264, IonQ 32, QuEra 100
- Number of cost-equivalent classical processors =
10^8
- Hardware slowdown base values =
IBM 10^3.78, IonQ 10^8.48, QuEra 10^5.1
- Classical clock speed =
5 GHz
- Connectivity penalty =
sqrt(q) for IBM, 1 for IonQ and QuEra
assumptions (7)
- domain assumption QEA occurs at t where Feas(t) = Adv(t), with Feas from roadmap/PLQR/QPS and Adv from runtime equality C(n,10^p) = 10^hws * Q(n) * P(QPS^-1(n))
- domain assumption Best-known worst-case runtimes: NFS e^((64/9 n)^(1/3) (ln n)^(2/3)) for factorization, n for search, n^2 ln n for Shor, sqrt(n) for Grover
- domain assumption QPS function takes one of three forms: exponential (2^q), linear (q), or logarithmic (log2(q))
- domain assumption Classical runtimes are fully parallelizable in the analysis; quantum parallelization is excluded
- ad hoc to paper Hardware slowdown decay is capped and PLQR is floored at 3
- ad hoc to paper Roadmap extrapolation is exponential beyond the last vendor data point by default
- ad hoc to paper An unstated ~100x gate-overhead factor is embedded in the gate-time-to-slowdown conversion
Cite this review
Pith. "Pith review of Introducing the Quantum Economic Advantage Online Calculator." pith.science (2026). https://pith.science/paper/MPUXZMOK
@misc{pith2026250821031,
author = {Pith},
title = {Pith review of: Introducing the Quantum Economic Advantage Online Calculator},
year = {2026},
howpublished = {\url{https://pith.science/paper/MPUXZMOK}},
note = {Machine review of arXiv:2508.21031}
}
read the original abstract
Developing a systematic view of where quantum computers will outperform classical ones is important for researchers, policy makers and business leaders. But developing such a view is challenging because quantum advantage analyses depend not only on algorithm properties, but also on a host of technical characteristics (error correction, gate speeds, etc.). Because various analyses make different assumptions about these technical characteristics, it can be challenging to make comparisons across them. In this paper, we introduce an open-access web-tool designed to make such comparisons easy. Built on the framework introduced by Choi, Moses, and Thompson (2023), it calculates when quantum systems will outperform classical computers for a given algorithmic problem. These estimates can be easily updated based on various assumptions for error correction, overhead, and connectivity. Different hardware roadmaps can also be used and algorithm running times can be customized to particular applications. It can currently be accessed at https://futuretech.mit.edu/quantum-economic-advantage-calculator. This integrated prediction tool also allows us to explore which technical factors are most important for quantum ``economic" advantage (outperforming on a cost-equivalent basis). Overall, we find that for some algorithms (e.g. Shor's) the timing of advantage is quite robust, whereas for others (e.g. Grover's) it is contingent, with numerous technical characteristics substantially impacting these dates. In the paper, we discuss both why this occurs and what we can learn from it.
Figures
Figures from the paper (4 more)
Reference graph
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