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arxiv: 2605.25983 · v1 · pith:CVTO5PBSnew · submitted 2026-05-25 · 🪐 quant-ph · cs.ET

Evaluating System-Level Fidelity with Peaked Random Circuits

Martin Brieger , Florian Kr\"otz , Minh Chung , Dieter Kranzlm\"uller This is my paper

Pith reviewed 2026-06-29 21:59 UTC · model grok-4.3

classification 🪐 quant-ph cs.ET
keywords quantum computingNISQ devicesfidelity benchmarkpeaked random circuitsquantum volumesystem-level performancesuperconducting qubitstrapped ions
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The pith

Peaked Random Circuits benchmark NISQ fidelity by measuring success at identifying a deterministic peak across qubit counts and depths.

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

The paper repurposes Peaked Random Circuits, first proposed to show quantum advantage, into a system-level fidelity benchmark for NISQ hardware. It runs matrices of these circuits at different qubit numbers and depths to test how reliably a processor can recover the single peaked output state amid noise, gate errors, and limited connectivity. The method is demonstrated on a superconducting platform and a trapped-ion platform. Results indicate the resulting scores match the precision of Quantum Volume while showing stronger response to interference effects. This supplies an architecture-agnostic way to compare computational reliability across quantum systems.

Core claim

Running a matrix of Peaked Random Circuits with varying qubit counts and circuit depths quantifies a quantum system's ability to identify the deterministic peak despite cumulative noise, gate errors, and connectivity constraints, yielding a high-precision fidelity metric comparable to Quantum Volume but with greater sensitivity to interference effects.

What carries the argument

Peaked Random Circuits (PRCs), which produce one reliably detectable peaked output state amid noise while remaining classically hard to simulate; the benchmark deploys matrices of PRCs at stepped qubit counts and depths to measure how well peak identification survives hardware imperfections.

If this is right

  • PRCs can be applied across superconducting and trapped-ion architectures to produce cross-platform reliability scores.
  • The benchmark detects interference effects with greater sensitivity than Quantum Volume on the tested hardware.
  • Matrices of PRCs with stepped qubit counts and depths supply a concrete procedure for quantifying cumulative effects of noise and connectivity limits.
  • The approach creates a framework for assessing computational reliability of NISQ systems that remains feasible on current devices.

Where Pith is reading between the lines

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

  • The same matrix protocol could be run on additional qubit numbers to map how fidelity degrades with scale on a given platform.
  • Differences in PRC scores between architectures might point to which error sources most limit peak detection in each technology.
  • If the greater interference sensitivity proves consistent, PRC benchmarks could complement Quantum Volume in hardware selection for algorithms sensitive to coherent errors.

Load-bearing premise

That success rates in recovering the peaked output across a range of circuit sizes and depths accurately reflect overall system fidelity under real noise and error conditions.

What would settle it

If PRC-derived fidelity scores on the same devices fail to track independent error-rate measurements or Quantum Volume scores in a consistent way, the claim that PRC matrices provide a comparable high-precision metric would not hold.

Figures

Figures reproduced from arXiv: 2605.25983 by Dieter Kranzlm\"uller, Florian Kr\"otz, Martin Brieger, Minh Chung.

Figure 1
Figure 1. Figure 1: Mirror architecture of the Peaked Random Circuits (PRCs) we use [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 3
Figure 3. Figure 3: Probability of the circuit to output the target, peak bitstring of our set [PITH_FULL_IMAGE:figures/full_fig_p003_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Successful recoveries of the peaked bitstring by the circuits’ depth and [PITH_FULL_IMAGE:figures/full_fig_p006_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Difference in the quality of peak identification between the AQT20 [PITH_FULL_IMAGE:figures/full_fig_p007_5.png] view at source ↗
read the original abstract

Quantum computing is transitioning from experimental prototypes to commercially available turnkey systems, making architecture-agnostic performance metrics essential for cross-platform comparison. Peaked Random Circuits (PRCs) have recently been proposed as a viable path to demonstrate quantum advantage on NISQ devices: a quantum processor can reliably detect a single, peaked output state amid background noise, yet the circuits' characteristics render classical simulation infeasible. In this paper, we repurpose PRCs as a system-level fidelity benchmark. By successively running a matrix of PRCs with varying qubit counts and circuit depths, we quantify a system's ability to identify the deterministic peak despite cumulative noise, gate errors, and connectivity constraints. We apply the benchmark on IQM's superconducting and AQT's trapped-ion architectures. Our results show that PRCs provide a high-precision metric comparable to Quantum Volume while exhibiting greater sensitivity to interference effects. Consequently, PRCs enable a robust framework for assessing the computational reliability of NISQ hardware across platforms.

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

1 major / 1 minor

Summary. The manuscript proposes repurposing Peaked Random Circuits (PRCs) as an architecture-agnostic system-level fidelity benchmark for NISQ devices. It runs matrices of PRCs with varying qubit counts and depths on IQM superconducting and AQT trapped-ion hardware, claims the resulting success probabilities quantify a system's ability to identify the deterministic peak amid noise and errors, and concludes that PRCs yield a high-precision metric comparable to Quantum Volume but with greater sensitivity to interference effects.

Significance. If the central claim holds and the ideal peak can be obtained without circularity, the work would supply a new cross-platform benchmark with potential advantages in sensitivity. The manuscript does not, however, supply machine-checked proofs, reproducible code, or parameter-free derivations that would strengthen the assessment.

major comments (1)
  1. [Abstract] Abstract: The claim that PRC characteristics 'render classical simulation infeasible' directly conflicts with the requirement to compare measured success probabilities against a known 'deterministic peak' probability in order to compute fidelity. No section of the manuscript resolves this by providing a non-simulation method for identifying the peak at the qubit counts and depths used in the matrix, nor does it restrict the benchmark to simulable sizes while preserving the 'system-level' and 'quantum advantage' framing.
minor comments (1)
  1. [Abstract] The abstract asserts results on sensitivity and comparability but supplies no methods details, data, error bars, or analysis steps; these must be added for the central claim to be evaluable.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the careful review and for identifying the tension in our abstract. We agree that the current wording creates an unresolved conflict between the claim of classical intractability and the need for a known peak probability, and that the manuscript does not currently supply an explicit non-simulation method or size restriction. We address this point below and will revise accordingly.

read point-by-point responses

  1. Referee: [Abstract] Abstract: The claim that PRC characteristics 'render classical simulation infeasible' directly conflicts with the requirement to compare measured success probabilities against a known 'deterministic peak' probability in order to compute fidelity. No section of the manuscript resolves this by providing a non-simulation method for identifying the peak at the qubit counts and depths used in the matrix, nor does it restrict the benchmark to simulable sizes while preserving the 'system-level' and 'quantum advantage' framing.

    Authors: We accept the criticism as valid. The abstract's phrasing is imprecise and does not resolve the logical tension. In the PRC construction used in the work, the target peak output state is chosen explicitly during circuit generation, so its identity is known a priori; the measured success probability is simply the probability of observing that specific state. However, obtaining the precise ideal probability value for normalization does rely on classical simulation for the depths and widths reported. No section currently explains this distinction or restricts the benchmark to simulable regimes. We will (1) revise the abstract to remove or qualify the 'infeasible' claim, (2) add a dedicated methods subsection describing how the peak state is identified by construction, and (3) explicitly limit the current benchmark results to simulable sizes while noting that the same protocol could be applied at larger scales where only the peak state (not the full distribution) needs to be targeted. These changes will be made in the revised manuscript. revision: yes

Circularity Check

0 steps flagged

No significant circularity; benchmark repurposing is empirical and self-contained

full rationale

The paper's core step is to run a matrix of PRCs on hardware at varying qubit counts and depths, then report measured success probabilities against the known ideal peak as a fidelity score. This is a direct empirical procedure with no equations shown that reduce the output to a fitted parameter or self-referential definition. The abstract's intractability claim applies to the regime where PRCs demonstrate advantage, while the benchmark application is presented as feasible on the tested systems; no derivation chain equates the fidelity metric to its own inputs by construction. No self-citation load-bearing steps, uniqueness theorems, or ansatzes are invoked in the provided text. The result remains an independent cross-platform comparison.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Only the abstract is available; no details on free parameters, axioms, or invented entities are provided.

pith-pipeline@v0.9.1-grok · 5700 in / 973 out tokens · 31992 ms · 2026-06-29T21:59:58.164483+00:00 · methodology

discussion (0)

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Reference graph

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