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Quantum Software Team Aarhus

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Quantum computing aims at faster computations by using superposition and entanglement of qubits. This could revolutionize entire industries – from pharmaceuticals and materials science to finance and logistics. Yet the promise of quantum computing is still limited by today’s hardware. Current devices operate in the so-called NISQ era (Noisy Intermediate-Scale Quantum), where qubits are scarce, error-prone, and difficult to control. Fault-tolerant quantum computing requires quantum error correction, whose scalability is currently limited. Quantum software plays a critical role in practical quantum computing, to bridge the gap from applications to hardware.

“Quantum Software” refers to programs running on quantum computers and to the design-automation tools to construct such quantum programs. Research on quantum software investigates high-level quantum programming languages, compiler techniques, and algorithms for automated synthesis, optimization, verification, and simulation of quantum programs. Together, these techniques support a long-term vision of building a quantum software stack that bridges the gap between high-level quantum algorithms and low-level circuits.

Quantum Circuit Optimization

Quantum algorithms are often described at a high level, but to run them on hardware, they must be compiled into quantum circuits. These circuits specify the exact operations performed on qubits. However, the translation from algorithms to circuits is rarely efficient: the resulting circuits are often far larger and noisier than necessary. Each extra operation increases noise and reduces reliability. Quantum circuit optimization – finding smaller, faster, and less noisy equivalents of a given circuit – is therefore one of the key challenges for enabling near-term real-world quantum applications. Optimized circuits not only increase accuracy on today’s noisy machines but also reduce the costly overhead of quantum error correction, which is needed for future, fault-tolerant quantum computers. 

News

People

Staff

Postdoc

  • Irfansha Shaik

PhD students

  • Adam Husted Kjelstrøm
  • Jens Emil Christensen
  • Kostiantyn Viktorovych Milkevych

Projects


Circuit Optimization for Quantum Error Correction

We explore efficient implementations of quantum error correction codes, an essential step toward scaling quantum computing from today’s noisy devices to fully fault-tolerant quantum computers. 

  • Funding: 2 PhD students NQCP (Novo Nordisk Foundation Quantum Computing Programme)
  • Partner: NQCP, AU Dept. of Physics
  • PI: Jaco van de Pol, Nikolaj Zinner
  • Researchers: Kostiantyn V. Milkevych, Asbjørn F. Teilmann, Jaco van de Pol, Nikolaj Zinner

QoptiQ - The Quest for Optimal Quantum Circuits

QoptiQ develops algorithms that go beyond the rough shortcuts used in today’s quantum compilers. We aim for circuits that are mathematically proven to be optimal for gate count and circuit depth, also handling hardware-specific connectivity constraints. 

  • Funding: PhD scholar DeiC DQAA (Danish Quantum Algorithms Academy)
  • PI: Jaco van de Pol
  • Researchers: Jens Emil Christensen, Andreas Pavlogiannis, Jaco van de Pol

Automated Planning for Quantum Circuit Optimization

We use Satisfiability Solving and Automated Planning to synthesize optimal layout-aware quantum circuits, focusing on minimizing the number of the 2-qubit CNOT gates and circuit depth.

  • Funding: Business Postdoc IFD (Innovation Fund Denmark)
  • PI: Jaco van de Pol, Allan Grønlund
  • Partner: Kvantify
  • Researchers: Irfansha Shaik, Jaco van de Pol

Publications

Peer reviewed:

  • Irfansha Shaik and Jaco van de Pol. CNOT-Optimal Clifford Synthesis as SAT. In: 28th IC on Theory and Applications of Satisfiability Testing (SAT), 2025. [DOI] [arXiv]
  • Anna B. Jakobsen, Anders B. Clausen, Jaco van de Pol, Irfansha Shaik. Depth-Optimal Quantum Layout Synthesis as SAT. In: 28th IC on Theory and Applications of Satisfiability Testing (SAT), 2025. [DOI] [arXiv]
  • Jens E. Christensen, Søren F. Jørgensen, Andreas Pavlogiannis, Jaco van de Pol. On Exact Sizes of Minimal CNOT Circuits. In: Proc. 17th IC on Reversible Computation (RC), 2025. [DOI] [arXiv]
  • Irfansha Shaik and Jaco van de Pol. Optimal layout synthesis for deep quantum circuits on NISQ processors with 100+ qubits. In: IC on Theory and Applications of Satisfiability Testing (SAT), 2024. [DOI] [arXiv]
  • Irfansha Shaik and Jaco van de Pol. Optimal layout-aware CNOT circuit synthesis with qubit permutation. In ECAI, volume 392 of Frontiers in Artificial Intelligence and Applications, 2024. [DOI] [arXiv]
  • Irfansha Shaik and Jaco van de Pol. Optimal layout synthesis for quantum circuits as classical planning. In: IEEE/ACM IC on Computer Aided Design (ICCAD), 2023. [DOI] [arXiv]

Technical Reports:

  • Adam Husted Kjelstrøm, Andreas Pavlogiannis, Jaco van de Pol. Exact Quantum Circuit Optimization is co-NQP-hard. Quant-ph arXiv:2510.16420, 2025. [arXiv]
  • Adam Husted Kjelstrøm, Andreas Pavlogiannis, Jaco van de Pol. Efficient Simulation of High-Level Quantum Gates. Quant-ph arXiv:2507.04337, 2025. [arXiv]
  • Kostiantyn V. Milkevych, Jaco van de Pol, Irfansha Shaik. Practical Subarchitectures for Optimal Quantum Layout Synthesis. Quant-ph arXiv:2507.12976, 2025. [arXiv]

Software

Find us on Github: https://github.com/Quantum-Software-Aarhus

Repositories:

  • Q-Synth: Quantum Circuit Synthesis and Layout Synthesis, using SAT solvers and Classical Planning
  • CNOTter: CNOT minimization, using group theory (symmetries) and concurrent hashtables

Partners and Links