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arxiv: 2605.02727 · v2 · submitted 2026-05-04 · 🪐 quant-ph · cs.DC

Distributed Quantum Circuit Optimisation: Evaluating Global and Local encodings

Pith reviewed 2026-05-12 03:07 UTC · model grok-4.3

classification 🪐 quant-ph cs.DC
keywords distributed quantum computingquantum circuit optimizationcircuit partitioningtelegatecompilation overheadglobal vs local optimizationhybrid optimization
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The pith

Circuit optimisation does not uniformly benefit distributed quantum execution, with global, local, and hybrid strategies trading off computational, communication, and compilation costs differently.

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

This paper compares three ways to optimise quantum circuits before or after they are split across multiple processors in a distributed architecture. Global optimisation is applied to the full circuit first, local optimisation is applied only to the parts on each processor, and a hybrid combines both. Using telegate-based partitioning on a large set of quantum algorithms, the work measures resulting gate counts, circuit depth, non-local gates that require communication, and the time to compile. Global optimisation cuts overall resources and preprocessing time most effectively. Local optimisation unexpectedly lowers communication needs without being designed for it. The hybrid reduces both resource types but takes far longer to prepare.

Core claim

Using a large benchmark suite of quantum algorithms and telegate-based partitioning, the study shows that global circuit optimisation minimises computational resources like gate counts and circuit depth while achieving the lowest compilation overhead. Local optimisation, applied after partitioning, can reduce communication cost by lowering induced non-local gates even without being explicitly communication-aware. The hybrid strategy reduces both computational and communication overheads but incurs significantly higher compilation time.

What carries the argument

Comparison of global optimisation (full circuit before partition), local optimisation (per-partition after), and hybrid strategies, evaluated via telegate-based partitioning that counts non-local gates as communication cost.

If this is right

  • Global optimisation produces the smallest total gate counts, shallowest depth, and fastest compilation for distributed workloads.
  • Local optimisation can decrease the number of non-local gates that must cross processors even though it ignores communication during its passes.
  • Hybrid optimisation simultaneously lowers both computational resources and communication overhead.
  • No single strategy improves every measured cost at once; each choice creates a distinct trade-off profile.

Where Pith is reading between the lines

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

  • This suggests distributed quantum compilers could benefit from optimisation passes that explicitly track and minimise non-local operations rather than applying local tweaks after the fact.
  • The hybrid approach's high compilation time points to a possible bottleneck for scaling to larger algorithms where preprocessing must stay fast.
  • Results indicate that benchmarks focused only on gate count may miss communication savings available from simple local optimisation.

Load-bearing premise

The large benchmark suite of quantum algorithms and telegate-based partitioning provide a representative approximation of computational, communication, and classical preprocessing costs in real distributed quantum architectures.

What would settle it

Running the same optimised distributed circuits on actual multi-processor quantum hardware and measuring real execution time, communication latency, and error rates against the paper's approximated gate counts and overheads would test whether the reported benefits hold.

Figures

Figures reproduced from arXiv: 2605.02727 by Majid Haghparast, Maria Gragera Garces.

Figure 1
Figure 1. Figure 1: Computational resource comparison across optimi view at source ↗
Figure 2
Figure 2. Figure 2: Mean inter-QPU communication cost under different view at source ↗
read the original abstract

As distributed quantum architectures begin to emerge, understanding the interaction between quantum circuit optimisation and circuit partitioning becomes increasingly important. In this work, we study how circuit optimisation influences distributed quantum workloads under system-level trade-offs. We compare three compilation strategies (global optimisation, local optimisation, and a hybrid approach) across a large benchmark suite of quantum algorithms. Using telegate-based partitioning, we evaluate the resulting distributed circuits in terms of gate counts, circuit depth, the number of induced non-local gates, and compilation overhead, thereby approximating computational, communication, and classical preprocessing costs. Our results show that circuit optimisation does not uniformly benefit distributed execution. Global optimisation minimises computational resources and achieves the lowest compilation overhead. Local optimisation can reduce communication cost even though it is not explicitly communication-aware. The hybrid strategy can simultaneously reduce both computational and communication overhead, but at the expense of significantly increased compilation time.

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 examines the effects of quantum circuit optimization on distributed quantum execution under telegate-based partitioning. It compares three strategies—global optimization, local optimization, and a hybrid approach—across a large benchmark suite of quantum algorithms. The evaluation uses metrics of gate counts, circuit depth, induced non-local gates, and compilation overhead to approximate computational, communication, and classical preprocessing costs. The central claim is that optimization does not uniformly benefit distributed circuits: global optimization minimizes computational resources and compilation overhead, local optimization reduces communication cost despite not being communication-aware, and the hybrid strategy reduces both computational and communication overhead at the expense of significantly higher compilation time.

Significance. If the reported empirical trade-offs are reproducible and the benchmark suite is representative, the work would offer useful guidance on selecting optimization strategies for emerging distributed quantum architectures, clarifying that global, local, and hybrid approaches produce distinct impacts on resource and overhead metrics. However, the absence of any methodology, data, or implementation details in the provided manuscript makes it impossible to assess whether these distinctions are correctly measured or generalizable.

major comments (2)
  1. Abstract: the manuscript asserts specific comparative outcomes ('Global optimisation minimises computational resources...', 'Local optimisation can reduce communication cost...', 'The hybrid strategy can simultaneously reduce both...') but supplies no methodology, benchmark list, optimization implementations, partitioning algorithm, metric definitions, raw data, error bars, or statistical analysis, so the claims cannot be verified or reproduced from the text.
  2. Abstract: the evaluation is said to approximate 'computational, communication, and classical preprocessing costs' via gate counts, depth, non-local gates, and overhead, yet no concrete definitions, formulas, or measurement procedures are given, leaving open whether the reported non-uniform benefits follow from the chosen metrics or from unstated assumptions about the telegate model.
minor comments (1)
  1. The title refers to 'encodings' while the abstract discusses 'optimisation' and 'compilation strategies'; a brief clarification of how the two concepts relate would improve readability.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their review and for highlighting the need for greater clarity on methodology and metrics. We address each major comment below. The full manuscript contains the benchmark details, implementations, and metric definitions referenced in the abstract; we are prepared to revise the abstract for improved self-containment where feasible.

read point-by-point responses
  1. Referee: Abstract: the manuscript asserts specific comparative outcomes ('Global optimisation minimises computational resources...', 'Local optimisation can reduce communication cost...', 'The hybrid strategy can simultaneously reduce both...') but supplies no methodology, benchmark list, optimization implementations, partitioning algorithm, metric definitions, raw data, error bars, or statistical analysis, so the claims cannot be verified or reproduced from the text.

    Authors: The abstract summarises the principal empirical outcomes of the study. The complete manuscript specifies the benchmark suite, the three optimisation strategies and their implementations, the telegate-based partitioning procedure, all metric definitions, and the full set of results including any statistical considerations. We can revise the abstract to include a short clause directing readers to the relevant sections for full reproducibility. revision: partial

  2. Referee: Abstract: the evaluation is said to approximate 'computational, communication, and classical preprocessing costs' via gate counts, depth, non-local gates, and overhead, yet no concrete definitions, formulas, or measurement procedures are given, leaving open whether the reported non-uniform benefits follow from the chosen metrics or from unstated assumptions about the telegate model.

    Authors: The main text defines each proxy metric explicitly: gate count and depth for computational cost, number of induced non-local gates for communication cost under the telegate model (where non-local operations are realised via remote gates), and measured compilation time for classical preprocessing overhead. These choices follow directly from the telegate execution model described in the paper. We will add a brief clarifying sentence to the abstract if length permits. revision: partial

Circularity Check

0 steps flagged

Empirical benchmark evaluation exhibits no circularity

full rationale

The paper's central claims consist of direct empirical observations from comparing global, local, and hybrid optimization strategies across a benchmark suite under telegate-based partitioning, using measured metrics of gate counts, depth, non-local gates, and overhead. No equations, derivations, fitted parameters, predictions, or self-citations are present in the available text that would reduce any result to its inputs by construction. The evaluation is self-contained against external benchmarks and does not invoke uniqueness theorems, ansatzes, or renamings that loop back to prior assumptions.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The central claim rests on the assumption that telegate partitioning and the chosen metrics validly approximate real distributed quantum costs, plus the representativeness of the benchmark suite; no free parameters or invented entities are evident from the abstract.

axioms (1)
  • domain assumption Telegate-based partitioning is a valid model for distributed quantum computation costs.
    Invoked to evaluate non-local gates and communication overhead in the distributed setting.

pith-pipeline@v0.9.0 · 5419 in / 1339 out tokens · 82352 ms · 2026-05-12T03:07:12.009110+00:00 · methodology

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Reference graph

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