Quantum Computing’s Flexible Future: ReQISC Redefines Control

Author: Denis Avetisyan

A new full-stack framework promises to optimize quantum computations by tightly integrating hardware and software design.

ReQISC establishes a system for engineering arbitrary SU(4) gates through a time-optimal microarchitecture and a three-stage compilation framework, ultimately expressing this functionality via the {Can, U3} gate set—a foundational step towards programmable quantum computation.

Researchers present ReQISC, a reconfigurable quantum computer microarchitecture and compiler co-design utilizing an SU(4)-based instruction set to minimize gate count and enhance performance through optimized pulse control.

Despite advances in quantum hardware, performance remains limited by gate fidelity and compilation overhead, hindering the practical realization of more expressive instruction set architectures. This paper introduces ‘ReQISC: A Reconfigurable Quantum Computer Microarchitecture and Compiler Co-Design’, a full-stack framework that leverages a reconfigurable microarchitecture and SU(4)-based instruction set to dramatically reduce gate counts and pulse durations. By co-designing hardware and a novel compilation pipeline, ReQISC achieves a 4.97-fold reduction in pulse duration for 2Q gates compared to conventional schemes. Could this approach finally unlock the theoretical potential of continuous ISAs and pave the way for scalable, high-performance quantum computation?

Navigating the Limits of Quantum Hardware

Current Noisy Intermediate-Scale Quantum (NISQ) devices face limitations in coherence and gate fidelity, restricting the complexity of solvable problems. Achieving practical quantum advantage requires overcoming these hardware constraints. Error mitigation and improved qubit control are essential, but scalability remains a significant obstacle due to Calibration Overhead. Research focuses on novel architectures—different qubit connectivity, dynamic allocation, and error-resilient circuits—prioritizing system-level coherence over sheer computational power.

Advancements in architectural support are paving the way for achieving quantum advantage.

ReQISC: A Holistic Framework for Quantum Optimization

The ReQISC framework offers a full-stack solution—integrating quantum compilation, Instruction Set Architecture (ISA) design, and precise Pulse Control—to efficiently map algorithms onto physical qubits. Leveraging the expressiveness of the SU(4) ISA enables optimal-duration gates and simplified circuits. Theoretical analysis demonstrates potential gate count reductions, and the microarchitecture employs a unified control scheme with appended one-qubit corrections for enhanced fidelity.

The ReQISC microarchitecture directly implements arbitrary two-qubit gates in a unified control scheme, utilizing common coupling forms and standard Rabi drives with control parameters to generate evolutions locally equivalent to target unitaries, and achieving exact implementation through appended one-qubit corrections.

Streamlining Quantum Circuits Through Advanced Synthesis

ReQISC employs Hierarchical Synthesis to decompose complex circuits into manageable blocks, reducing synthesis cost through parallelization. Techniques like DAG Compacting and Approximate Commutation further streamline circuits, minimizing qubit requirements. The Mirroring Technique transforms near-identity gates for easier execution, reducing Calibration Overhead. Haar-Random Synthesis benchmarks ISAs, demonstrating ReQISC’s 55.6% reduction in 2Q gate count.

Hardware implementation of the ReQISC microarchitecture features a mirroring strategy for near-identity corners, a gate time landscape computed under XY coupling indicating gate durations, and pulse control subschemes under both XY and XX couplings, with local drive amplitudes scaling according to equivalent canonical gates within each gate family.

Towards Scalable Quantum Computation: A Systems-Level Approach

The ReQISC framework optimizes near-term quantum circuits by addressing limitations in NISQ devices, accelerating progress towards Fault-Attenuated Symmetric Shorcode Decoding (FASQ) devices. Achieving an average gate fidelity of 99.37% on superconducting transmon qubits, ReQISC’s integrated ISA design, compilation, and pulse control represent a cohesive platform for innovation. Ultimately, progress demands refining the language of instruction—not simply adding more qubits.

Hierarchical synthesis effectively reduces the two-qubit count of the alu-v2_33 circuit from 17 to 11 by partitioning it into three-qubit blocks, applying approximate synthesis, and utilizing two-tier partitioning with DAG compacting.

The pursuit of ReQISC, with its SU(4)-based instruction set and co-designed microarchitecture, embodies a holistic approach to quantum computation. It recognizes that gains in one area – instruction set design or gate synthesis, for instance – are inextricably linked to the success of the entire system. This echoes the sentiment of Louis de Broglie: “It is in the interplay between theory and experiment that progress is made in science.” The framework’s focus on Hamiltonian steering and minimizing gate count isn’t simply about optimization; it’s about understanding how the components of a quantum system interact, and designing them to function as a coherent whole. If the system survives on duct tape, it’s probably overengineered—ReQISC aims for elegant simplicity through deep integration, a principle essential for realizing practical quantum advantage.

What’s Next?

The introduction of ReQISC, with its SU(4) foundation, highlights a persistent tension: the relentless pursuit of more expressive instruction sets. Yet, one must ask, what is actually being optimized for? Reduced gate count is a worthy goal, but merely shifting complexity from compilation to the control plane—as Hamiltonian steering inevitably does—risks obscuring fundamental limitations. The true metric lies not in minimizing superficial metrics, but in approaching the inherent limits of quantum control itself.

Future work must confront the practical realities of imperfect hardware. ReQISC’s reconfigurable microarchitecture offers a compelling path, but the benefit of adaptability diminishes rapidly with increased error rates. The field needs rigorous investigation into the interplay between ISA expressiveness, microarchitectural flexibility, and the inevitable noise that characterizes physical qubits. Simplicity is not minimalism; it is the discipline of distinguishing the essential—robustness and fidelity—from the accidental.

Ultimately, the success of approaches like ReQISC will depend on a holistic understanding of the quantum stack. It is not sufficient to optimize compilation in isolation. The architecture must be designed in concert with error correction strategies and, crucially, with a clear articulation of the target applications. Only then can the potential of reconfigurable quantum computation be fully realized, and the illusion of progress through complexity dispelled.

Original article: https://arxiv.org/pdf/2511.06746.pdf

Contact the author: https://www.linkedin.com/in/avetisyan/

Navigating the Limits of Quantum Hardware

ReQISC: A Holistic Framework for Quantum Optimization

Streamlining Quantum Circuits Through Advanced Synthesis

Towards Scalable Quantum Computation: A Systems-Level Approach

What’s Next?

See also: