LightStim: A Framework for QEC Protocol Evaluation and Prototyping with Automated DEM Construction

Dean Tullsen; Frank Mueller; Ming Wang; Narasinga Rao Miniskar; Sharanya Prabhu; Travis Humble; Xiang Fang; Yue Wu; Yufei Ding

arxiv: 2604.21472 · v2 · pith:IOMAVOYOnew · submitted 2026-04-23 · 🪐 quant-ph

LightStim: A Framework for QEC Protocol Evaluation and Prototyping with Automated DEM Construction

Xiang Fang , Ming Wang , Yue Wu , Sharanya Prabhu , Dean Tullsen , Narasinga Rao Miniskar , Frank Mueller , Travis Humble

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Yufei Ding

This is my paper

Pith reviewed 2026-05-09 22:27 UTC · model grok-4.3

classification 🪐 quant-ph

keywords quantum error correctiondetector error modelfault-tolerant quantum computingcircuit compilationlattice surgeryPauli tableauerror simulation

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The pith

LightStim automates Detector Error Model construction for quantum error correction protocols by maintaining an augmented Pauli tableau during circuit compilation.

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

The paper introduces a framework that builds the Detector Error Model required for end-to-end simulation of logical error rates automatically while the quantum circuit is compiled. It tracks Pauli operators together with measurement records in a tableau structure, eliminating any need for manual annotations or protocol-specific details. This removes the main bottleneck that has confined most rigorous evaluations to simple memory experiments. Cross-checks against existing implementations show identical detector and observable counts along with matching logical error rates. The same mechanism also supports rapid design and testing of previously unexplored protocols such as heterogeneous lattice surgery between different codes.

Core claim

By maintaining a Pauli tableau augmented with measurement records concurrently with circuit compilation, the framework constructs the complete set of detectors and observables required for the Detector Error Model of any quantum error correction protocol without protocol-specific input, as confirmed by exact matches in counts and logical error rates to public implementations across memory experiments, distillation circuits, and a novel heterogeneous cross-code lattice surgery design.

What carries the argument

A Pauli tableau augmented with measurement records that is updated in tandem with circuit compilation to automatically identify every detector and observable.

If this is right

Exact detector and observable counts match those from public implementations for all tested protocols.
Logical error rates remain consistent in simulations of memory experiments and end-to-end distillation circuits.
New protocol designs can be prototyped and evaluated without manual DEM construction.
A unified infrastructure supports systematic comparison across simple and complex quantum error correction schemes.

Where Pith is reading between the lines

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

Researchers could test a much larger space of custom error correction schemes without the overhead of hand-crafted annotations.
The approach may allow direct incorporation of device-specific noise models to produce more realistic performance predictions.
Systematic sweeps over many protocol variants become practical, potentially revealing hybrid designs that outperform current standards.

Load-bearing premise

That the information captured in the augmented Pauli tableau during compilation is sufficient to identify every detector and observable for arbitrary quantum error correction protocols.

What would settle it

An independently verified manual Detector Error Model for any protocol that produces a different detector count or a different logical error rate when simulated with the framework's output.

Figures

Figures reproduced from arXiv: 2604.21472 by Dean Tullsen, Frank Mueller, Ming Wang, Narasinga Rao Miniskar, Sharanya Prabhu, Travis Humble, Xiang Fang, Yue Wu, Yufei Ding.

**Figure 1.** Figure 1: (a) Dual burden on QEC protocol Compilation: Physical Circuit & DEM. (b) Sample Stim circuit. Physical operations specified by the protocol and the rest are all automated in LightStim. transformations is highly error-prone and unscalable; any mistake will provide incorrect information to the decoder and invalidate the LER evaluation. However, this tedious task can in fact be fully automated with correctnes… view at source ↗

**Figure 3.** Figure 3: Physical Circuit and DEM construction for surface code Z memory experiment. without errors, consecutive measurements must match, yielding a deterministic parity detector (e.g., 𝐷2 = 𝑚1⊕𝑚2). These detectors encode the information needed to infer where and what errors occurred in the circuit. (2) Logical Observable: Targets. A logical observable is also a deterministic parity of measurement records under no… view at source ↗

**Figure 2.** Figure 2: Pauli tableau representation of QEC systems. Stab: stabilizers; Log: logical operators. Update Rules. Beyond describing static structures, the Pauli tableau can track dynamic state evolution in Clifford circuits: Rule 1: Clifford Gates. A Clifford gate 𝐶 [39] maps any Pauli string 𝑃 to another Pauli string 𝐶𝑃𝐶† via conjugation. Rule 2: Pauli Measurements. Measuring a Pauli operator 𝑃 against the current ta… view at source ↗

**Figure 4.** Figure 4: Overview of LightStim’s Pauli Tracker workflow. The physical circuit drives a forward update of the recordaugmented Pauli tableau, triggering DEM construction upon encountering measurements. 3 LightStim Core: Pauli Tracker This section illustrates how LightStim’s core, Pauli tracker, constructs the DEM automatically and progressively as the physical circuit is compiled. The tracker maintains a Pauli table… view at source ↗

**Figure 5.** Figure 5: Three realizations of Bell state teleportation circuits: (a) transversal gates, (b,c) 𝑍𝑍/𝑋𝑋 lattice surgery. them into a surface code for reliable storage through LS-𝑍𝑍 measurement (circuit in Appendix A, [PITH_FULL_IMAGE:figures/full_fig_p007_5.png] view at source ↗

**Figure 7.** Figure 7: Evaluation of memory experiments. (a) Surface code family. (b) BB code family. (c) QEC efficiency: LER per physical qubit. (d) Effect of SE circuit design on LER. largest tested scale—thousands of qubits and tens of thousands of detectors—LightStim remains tractable and covers system sizes relevant to near-term FTQC experiments projected for the coming years. Scaling to substantially larger circuits may … view at source ↗

**Figure 8.** Figure 8: Comprehensive evaluation of logical operations. (a) Transversal gates and lattice surgery operations of unrotated surface code against the memory baseline; (b) State injection of rotated surface code; (b1)-(b3) Two SE round, full post-selection; (b4) Different post-selection schemes. |𝑍⟩ and |𝑋⟩ ( [PITH_FULL_IMAGE:figures/full_fig_p010_8.png] view at source ↗

**Figure 9.** Figure 9: LER of Bell-state teleportation circuit implemented in (a) transversal gates and (b,c) lattice surgery. 2. Distillation [PITH_FULL_IMAGE:figures/full_fig_p010_9.png] view at source ↗

**Figure 10.** Figure 10: Surface-PQRM CrossLS protocol. (a) Routing Overhead in Bell state teleportation. (b) Distilled output fidelity matching theoretical 7𝑝 3 𝑖𝑛. (c)(d) Surface-PQRM CrossLS protocol evaluation. 6.6 Surface-PQRM Lattice Surgery We present CrossLS as a case study demonstrating LightStim’s rapid prototyping capability for novel cross-code protocols. CrossLS teleports a logical state from a PQRM code to a surfa… view at source ↗

**Figure 11.** Figure 11: shows the teleportation circuit realized via LS and TG. Both initialize Code 1 in logical |+⟩𝐿 and the target state |𝜓⟩𝐿 on Code 2, followed by an initial SE round. Their subsequent operations differ based on the underlying protocol. The LS circuit ( [PITH_FULL_IMAGE:figures/full_fig_p015_11.png] view at source ↗

**Figure 12.** Figure 12: (a-c) Detector and logical observable construction in LS teleportation. (d-f) Detector construction in transversal CNOT gates, which naturally derives the correlated decoding technique. Code 2. LightStim natively and automatically tracks this end-to-end feed-forward propagation, which is a critical capability for compiling complex LS protocols. A.3 TG-based Teleportation [PITH_FULL_IMAGE:figures/full_fi… view at source ↗

**Figure 13.** Figure 13: The tick-accurate cross-code SE circuit scheduling for CrossLS protocol. teleporting |𝑍⟩ increases LER by ≈ 3 × 10−5 per routing unit at 𝑑 = 7, 𝑝 = 10−3 . For |𝑋⟩ teleportation via ZZ-LS, the feed-forward correction is still 𝑋 𝑏 , but applying 𝑋 to an 𝑋-eigenstate leaves it invariant. The 𝑍1𝑍2 outcome 𝑏 is therefore irrelevant to LER, decoupling the routing-distance effect entirely. The same argument ap… view at source ↗

read the original abstract

Fault-tolerant quantum computing increasingly demands rigorous, circuit-level evaluation of diverse quantum error correction (QEC) protocols and efficient prototyping of new ones. Such evaluation requires both the physical circuit and its Detector Error Model (DEM) to estimate end-to-end logical error rates. However, DEM construction today is performed by manual annotation, a tedious and error-prone process that effectively limits evaluation to simple memory experiments. We present LightStim, a framework that automates DEM construction concurrently with circuit compilation by maintaining a Pauli tableau augmented with measurement records, with no protocol-specific input required. We benchmark LightStim across protocols from memory experiments to end-to-end distillation circuits; cross-validation against public implementations confirms exact detector and observable counts and consistent logical error rates. Additionally, we demonstrate a novel heterogeneous cross-code lattice surgery design between surface and punctured quantum Reed-Muller codes. These capabilities together make LightStim a unified infrastructure for systematic QEC protocol evaluation and exploration. LightStim is open-sourced at https://github.com/QuTone/LightStim.

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.

Desk Editor's Note private letter to a colleague

LightStim automates DEM construction for QEC circuits via Pauli tableau tracking during compilation and validates it on memory, distillation, and a new cross-code lattice surgery example.

read the letter

The main point is that LightStim builds detector error models automatically by keeping an augmented Pauli tableau with measurement records as the circuit compiles, without any protocol-specific annotations or manual work. This directly tackles the tedious step that has kept most QEC evaluations limited to simple memory circuits. They show it produces exact detector and observable counts that match public implementations, and the resulting logical error rates are consistent across the tested cases. They also use the tool to put together a heterogeneous lattice surgery between surface and punctured Reed-Muller codes, which is a concrete demonstration of exploring new protocols faster. The validation is the strongest part: cross-checks against independent code give reproducible numbers rather than just internal consistency. That counts as real evidence the core procedure works for the protocols they ran. The soft spot is whether the tableau-plus-records bookkeeping catches every relevant error propagation once you move beyond the benchmark set. Circuits with heavy feed-forward, resets, or conditional branches could in principle create dependencies the current tracking misses, even if detector counts match on the examples shown. The paper tests distillation and the lattice surgery case, so it is not limited to trivial memory, but the claim of working for arbitrary protocols still rests on the assumption that no hidden propagations slip through. This paper is for people who actually run QEC simulations and want to iterate on new protocols without spending days annotating detectors. It is infrastructure rather than a new theorem, but the automation and the validation make it worth a serious referee. I would send it to peer review; the evidence is grounded enough that reviewers can check the edge cases and the code release.

Referee Report

2 major / 2 minor

Summary. The manuscript presents LightStim, a framework that automates construction of Detector Error Models (DEMs) for quantum error correction protocols concurrently with circuit compilation. It maintains a Pauli tableau augmented with measurement records and requires no protocol-specific annotations or manual inputs. The approach is benchmarked on protocols ranging from memory experiments to distillation circuits, with cross-validation against public implementations confirming exact detector and observable counts plus consistent logical error rates. It is further used to prototype a novel heterogeneous cross-code lattice surgery between surface and punctured quantum Reed-Muller codes.

Significance. If the tableau-based construction fully captures all relevant error propagations without omissions, LightStim would substantially lower the barrier to rigorous circuit-level QEC evaluation and enable systematic exploration of complex protocols. The cross-validation on multiple protocols and the concrete demonstration of a new heterogeneous design provide reproducible evidence of utility for the tested cases and constitute a clear strength.

major comments (2)

[Method section on Pauli tableau] Method section describing the Pauli tableau augmentation with measurement records: the central claim that this procedure yields a complete DEM for arbitrary QEC protocols (including those with mid-circuit measurements, resets, and feed-forward) rests on the assumption that all error propagations are tracked by the tableau updates. No explicit handling is shown for conditional branches or measurement-outcome-dependent logical observables, which could silently omit detectors even when counts match on the reported benchmarks.
[Validation and cross-code lattice surgery section] Validation and cross-code lattice surgery section: while exact detector/observable counts and consistent logical error rates are reported against public implementations, the manuscript does not detail how the heterogeneous cross-code operations (surface to punctured Reed-Muller) propagate errors across code boundaries or whether additional measurement records are implicitly required. This is load-bearing for the claim of no protocol-specific input.

minor comments (2)

[Figures and tables] Figure captions and table legends should explicitly state the error model parameters and number of shots used for the logical error rate comparisons to allow direct reproduction.
[Abstract] The abstract states 'no protocol-specific input required' but the text should clarify whether this includes the absence of any hidden annotations for resets or classical feed-forward in the circuit description language.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their thorough review and constructive feedback on our manuscript. We address each of the major comments below and will incorporate revisions to enhance the clarity and completeness of the presentation.

read point-by-point responses

Referee: [Method section on Pauli tableau] Method section describing the Pauli tableau augmentation with measurement records: the central claim that this procedure yields a complete DEM for arbitrary QEC protocols (including those with mid-circuit measurements, resets, and feed-forward) rests on the assumption that all error propagations are tracked by the tableau updates. No explicit handling is shown for conditional branches or measurement-outcome-dependent logical observables, which could silently omit detectors even when counts match on the reported benchmarks.

Authors: We thank the referee for highlighting this important aspect. The augmented Pauli tableau in LightStim is constructed to track error propagations through all operations, including mid-circuit measurements, resets, and feed-forward, by maintaining measurement records that capture outcome dependencies. However, we agree that the manuscript would benefit from more explicit description. In the revised version, we will add a new subsection in the Methods section explaining the handling of conditional branches and outcome-dependent observables. This will include pseudocode or a small example demonstrating that all relevant detectors are captured without omissions. We believe this will address the concern while maintaining the no-protocol-specific-input design. revision: yes
Referee: [Validation and cross-code lattice surgery section] Validation and cross-code lattice surgery section: while exact detector/observable counts and consistent logical error rates are reported against public implementations, the manuscript does not detail how the heterogeneous cross-code operations (surface to punctured Reed-Muller) propagate errors across code boundaries or whether additional measurement records are implicitly required. This is load-bearing for the claim of no protocol-specific input.

Authors: We appreciate the referee pointing out the need for greater detail in the cross-code lattice surgery demonstration. The LightStim framework handles cross-code operations by extending the measurement records across the boundary without requiring manual annotations, as the tableau augmentation is uniform. To strengthen this, we will revise the relevant section to provide a detailed breakdown of error propagation in the heterogeneous surgery, specifying the measurement records involved for interfacing the surface code with the punctured quantum Reed-Muller code. This will explicitly show that no additional protocol-specific inputs are needed beyond the circuit description. revision: yes

Circularity Check

0 steps flagged

No circularity: algorithmic DEM construction is a self-contained procedure validated against independent public implementations

full rationale

The paper describes LightStim as an algorithmic procedure that maintains a Pauli tableau augmented with measurement records during circuit compilation to automatically produce the DEM, requiring no protocol-specific input. This is presented as a direct implementation of standard Pauli tracking and measurement bookkeeping rather than a derivation that reduces to fitted parameters, self-definitions, or prior self-citations. Benchmarking relies on cross-validation against separate public implementations, which independently confirm detector/observable counts and logical error rates; this constitutes external evidence rather than self-referential support. No load-bearing steps invoke uniqueness theorems from the same authors, smuggle ansatzes via citation, or rename known results as new predictions. The skeptic concern about possible missed error propagations in complex protocols is a question of algorithmic completeness and correctness, not circularity in the reported construction.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 1 invented entities

The framework rests on standard quantum error assumptions rather than new fitted parameters or invented physical entities. The main addition is the software procedure itself.

axioms (2)

domain assumption Pauli errors dominate and can be tracked via tableau methods in quantum circuits
Core modeling choice for all QEC simulations; invoked to justify the tableau approach.
domain assumption Measurement records suffice to identify all detectors without protocol-specific rules
Central to the claim of no protocol-specific input required.

invented entities (1)

LightStim framework no independent evidence
purpose: Automate concurrent DEM construction for arbitrary QEC protocols
The framework is the primary contribution; no independent falsifiable evidence outside the paper is provided.

pith-pipeline@v0.9.0 · 5496 in / 1413 out tokens · 69268 ms · 2026-05-09T22:27:03.060496+00:00 · methodology

discussion (0)

Forward citations

Cited by 1 Pith paper

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Analytical and Compressed Simulation of Noisy Stabilizer Circuits
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Closed-form expressions and circuit compression enable efficient strong and weak simulation of noisy stabilizer circuits with non-deterministic measurements.