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arxiv: 2604.08674 · v1 · submitted 2026-04-09 · 🪐 quant-ph

Recognition: unknown

The MQT Compiler Collection: A Blueprint for a Future-Proof Quantum-Classical Compilation Framework

Lukas Burgholzer , Daniel Haag , Yannick Stade , Damian Rovara , Patrick Hopf , Robert Wille
Authors on Pith no claims yet

Pith reviewed 2026-05-10 17:02 UTC · model grok-4.3

classification 🪐 quant-ph
keywords quantum compilationMLIRquantum-classical integrationcompiler frameworkerror correctionhybrid algorithmsoptimization
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The pith

The MQT Compiler Collection provides an MLIR-based classical-first framework for the full quantum-classical compilation pipeline.

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

Modern quantum algorithms and error-correction schemes increasingly incorporate classical elements such as structured control flow and integration with high-performance computing. Quantum-first compilers have documented difficulties managing these elements and performing optimizations beyond basic gate cancellation. The paper proposes the MQT Compiler Collection as a blueprint built from the ground up on core MLIR concepts to translate high-level algorithms all the way to hardware-specific instructions while supporting complex optimizations. A reader would care because advancing hardware makes these hybrid programs necessary, and current tools limit what can be practically compiled and run.

Core claim

We present the MQT Compiler Collection, a blueprint for a future-proof quantum-classical compilation framework built on the Multi-Level Intermediate Representation (MLIR). After years of experience with the quantum-first approach and its shortcomings, we propose a framework that embraces core MLIR concepts to support the full compilation pipeline from high-level algorithms to hardware-specific instructions. The proposed architecture is designed from the ground up to support complex optimizations beyond, e.g., simple gate cancellation.

What carries the argument

The MQT Compiler Collection, an architecture that adopts core MLIR concepts to treat quantum and classical components uniformly across the entire compilation pipeline.

Load-bearing premise

That shifting to a classical-first MLIR-based approach will successfully overcome the documented shortcomings of quantum-first compilers when handling classical elements, structured control flow, and complex optimizations.

What would settle it

A side-by-side compilation and execution test of an error-correction scheme containing loops and conditionals, showing that the MQT framework applies advanced optimizations while a quantum-first compiler either fails or produces inferior results.

Figures

Figures reproduced from arXiv: 2604.08674 by Damian Rovara, Daniel Haag, Lukas Burgholzer, Patrick Hopf, Robert Wille, Yannick Stade.

Figure 1
Figure 1. Figure 1: The MQT Compiler Collection (mqt-cc) combines quantum and classical concepts to build a future-proof compilation framework. II. BACKGROUND AND RELATED WORK To ensure that this article is self-contained, we briefly review the relevant aspects of MLIR. Subsequently, we discuss related approaches and how they address the challenge of defining an infrastructure for quantum compilation. A. Multi-Level Intermedi… view at source ↗
Figure 2
Figure 2. Figure 2: The MQT Compiler Collection pipeline [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Abbreviated TableGen definition of the UnitaryOpInterface. Example 2. Consider the creation of a Bell pair. In the QC dialect, the reference semantics are evident: we allocate two qubits and apply operations to them sequentially. %q0 and %q1 represent the qubit references themselves, which are reused throughout the program. The data flow is implicit—defined only by the program order. QC_Bell_Pair.mlir %q0 … view at source ↗
read the original abstract

As the capabilities of quantum computing hardware continue to rise, algorithms that exploit them are becoming increasingly complex. These developments increase the need for sophisticated compilation frameworks that translate high-level algorithms into executable code. In the past, most solutions were built with a quantum-first approach and handled mostly pure quantum programs without classical elements such as structured control flow. However, developments in quantum algorithms, error correction, and optimization, as well as the integration into high-performance computing (HPC) environments, depend on such classical elements. As quantum-first approaches increasingly struggle to handle these concepts, classical-first approaches are becoming a promising alternative. In this work, we present the MQT Compiler Collection, a blueprint for a future-proof quantum-classical compilation framework built on the Multi-Level Intermediate Representation (MLIR). After years of experience with the quantum-first approach and its shortcomings, we propose a framework that embraces core MLIR concepts to support the full compilation pipeline from high-level algorithms to hardware-specific instructions. The proposed architecture is designed from the ground up to support complex optimizations beyond, e.g., simple gate cancellation. It is publicly available at https://github.com/munich-quantum-toolkit/core.

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

3 major / 2 minor

Summary. The manuscript proposes the MQT Compiler Collection as a blueprint for a quantum-classical compilation framework built on the Multi-Level Intermediate Representation (MLIR). It argues that quantum-first compilers struggle with classical elements such as structured control flow, which are increasingly important for modern quantum algorithms, error correction, and HPC integration. The authors present a classical-first MLIR-based architecture intended to support the full pipeline from high-level algorithms to hardware-specific instructions and to enable complex optimizations beyond simple gate cancellation. The framework is stated to be publicly available on GitHub.

Significance. If the proposed architecture can be realized with concrete dialect definitions and demonstrated optimizations, it could provide a more extensible and future-proof compilation infrastructure for hybrid quantum-classical programs. This would be valuable for integrating quantum computing with classical control logic and advanced error-correction schemes, potentially accelerating practical algorithm development. The public availability of the code is a positive step toward reproducibility, though the current manuscript offers only high-level design intent without empirical validation or worked examples.

major comments (3)
  1. Abstract: The central claim that the architecture 'is designed from the ground up to support complex optimizations beyond, e.g., simple gate cancellation' and handles structured control flow is presented only as architectural intent. No concrete MLIR dialect definitions, operation semantics for qubit measurement feedback, or optimization examples are supplied, leaving the assertion that this overcomes quantum-first limitations as an unverified assumption rather than a demonstrated property.
  2. Abstract / design description: The manuscript provides no benchmarks, empirical comparisons to existing quantum-first compilers, or correctness arguments for the full compilation pipeline in real algorithms and error-correction schemes. This is load-bearing for the claim that shifting to a classical-first MLIR approach will succeed where prior methods fail.
  3. Motivation and proposal sections: The positioning as a response to shortcomings of earlier quantum-first work by the same group is not accompanied by a specific mapping of how MLIR concepts resolve documented issues with classical elements, making the novelty and advantage claims difficult to evaluate.
minor comments (2)
  1. The abstract could be strengthened by briefly naming the specific MLIR dialects or passes envisioned for quantum operations and classical control to improve immediate clarity for readers.
  2. Consider including a diagram of the proposed compilation pipeline and a table contrasting the new framework with prior quantum-first approaches; this would aid presentation without altering the technical content.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for their thoughtful and constructive review. We appreciate the acknowledgment of the potential value of an MLIR-based classical-first architecture for hybrid quantum-classical compilation. Below we respond point by point to the major comments. As the manuscript presents a blueprint with accompanying open-source code rather than a full empirical evaluation, we clarify the intended scope while outlining targeted revisions to address the concerns raised.

read point-by-point responses

  1. Referee: Abstract: The central claim that the architecture 'is designed from the ground up to support complex optimizations beyond, e.g., simple gate cancellation' and handles structured control flow is presented only as architectural intent. No concrete MLIR dialect definitions, operation semantics for qubit measurement feedback, or optimization examples are supplied, leaving the assertion that this overcomes quantum-first limitations as an unverified assumption rather than a demonstrated property.

    Authors: We agree that the manuscript presents the claims at the level of architectural design. The concrete MLIR dialect definitions, including operations for quantum gates, classical control flow, and measurement feedback, are implemented in the publicly available GitHub repository. We will revise the manuscript to include explicit references to the relevant dialect files (e.g., the quantum and control-flow dialects) and add a short worked example in the design section illustrating an optimization pass that uses structured control flow for feedback in error-correction circuits. This will make the claims more concrete without altering the blueprint focus of the paper. revision: partial

  2. Referee: Abstract / design description: The manuscript provides no benchmarks, empirical comparisons to existing quantum-first compilers, or correctness arguments for the full compilation pipeline in real algorithms and error-correction schemes. This is load-bearing for the claim that shifting to a classical-first MLIR approach will succeed where prior methods fail.

    Authors: The manuscript is explicitly positioned as a blueprint describing the framework architecture and its rationale, not as an empirical evaluation paper. Consequently, it does not contain benchmarks or direct comparisons. The open-source implementation allows independent verification and future benchmarking. We will add a brief discussion clarifying the scope and noting that preliminary correctness arguments and usage examples are available in the repository. We acknowledge that empirical validation is important and intend to pursue it in follow-up work. revision: partial

  3. Referee: Motivation and proposal sections: The positioning as a response to shortcomings of earlier quantum-first work by the same group is not accompanied by a specific mapping of how MLIR concepts resolve documented issues with classical elements, making the novelty and advantage claims difficult to evaluate.

    Authors: We will revise the motivation and proposal sections to provide a more explicit mapping. We plan to insert a structured comparison (e.g., a table) that directly links specific limitations observed in our prior quantum-first compilers—such as handling of classical loops, measurement feedback, and integration with HPC control logic—to corresponding MLIR mechanisms, including multi-level dialect composition, region-based control flow, and the pass infrastructure. This will strengthen the evaluation of novelty and advantage. revision: yes

Circularity Check

0 steps flagged

No significant circularity in the architectural blueprint proposal

full rationale

The paper presents an original design proposal for an MLIR-based quantum-classical compiler framework motivated by observed limitations of prior quantum-first approaches. No derivation chain, equations, or predictions are offered that reduce by construction to the paper's own inputs, fitted parameters, or self-referential definitions. The central claims consist of high-level architectural choices and stated advantages of MLIR concepts for handling control flow and optimizations; these are independent proposals rather than tautological restatements. Any references to the authors' prior experience constitute normal context-setting and do not function as load-bearing self-citations that force the result.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The central claim rests on the domain assumption that MLIR's multi-level design can be extended to handle quantum operations, classical control flow, and advanced optimizations without introducing new fundamental limitations; no free parameters or invented entities are introduced in the abstract.

axioms (1)
  • domain assumption MLIR provides a suitable foundation for a future-proof quantum-classical compilation framework that supports complex optimizations.
    The proposal assumes MLIR's extensibility and dialect system will enable the required pipeline without providing specific evidence or counterexamples in the given text.

pith-pipeline@v0.9.0 · 5519 in / 1221 out tokens · 47764 ms · 2026-05-10T17:02:06.997111+00:00 · methodology

discussion (0)

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Reference graph

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