Mapping Quantum Circuits to Modular Architectures with QUBO

Medina Bandic*, Luise Prielinger*, Jonas Nublein, Anabel Ovide, Santiago Rodrigo, Hans Van Someren*, Gayane Vardoyan*, Carmen G. Almudever, Sebastian Feld*, More Authors

*Corresponding author for this work

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review


Modular quantum computing architectures are a promising alternative to monolithic QPU (Quantum Processing Unit) designs for scaling up quantum devices. They refer to a set of interconnected QPUs or cores consisting of tightly coupled quantum bits that can communicate via quantum-coherent and classical links. In multi-core architectures, it is crucial to minimize the amount of communication between cores when executing an algorithm. Therefore, mapping a quantum circuit onto a modular architecture involves finding an optimal assignment of logical qubits (qubits in the quantum circuit) to different cores with the aim to minimize the number of expensive inter-core operations while adhering to given hardware constraints. In this paper, we propose for the first time a Quadratic Unconstrained Binary Optimization (QUBO) technique to encode the problem and the solution for both qubit allocation and inter-core communication costs in binary decision variables. To this end, the quantum circuit is split into slices, and qubit assignment is formulated as a graph partitioning problem for each circuit slice. The costly inter-core communication is reduced by penalizing inter-core qubit communications. The final solution is obtained by minimizing the overall cost across all circuit slices. To evaluate the effectiveness of our approach, we conduct a detailed analysis using a representative set of benchmarks having a high number of qubits on two different multi-core architectures. Our method showed promising results and performed exceptionally well with very dense and highly-parallelized circuits that require on average 0.78 inter-core communications per two-qubit gate.

Original languageEnglish
Title of host publicationProceedings - 2023 IEEE International Conference on Quantum Computing and Engineering, QCE 2023
EditorsHausi Muller, Yuri Alexev, Andrea Delgado, Greg Byrd
PublisherInstitute of Electrical and Electronics Engineers (IEEE)
Number of pages12
ISBN (Electronic)9798350343236
Publication statusPublished - 2023
Event4th IEEE International Conference on Quantum Computing and Engineering, QCE 2023 - Bellevue, United States
Duration: 17 Sept 202322 Sept 2023

Publication series

NameProceedings - 2023 IEEE International Conference on Quantum Computing and Engineering, QCE 2023


Conference4th IEEE International Conference on Quantum Computing and Engineering, QCE 2023
Country/TerritoryUnited States

Bibliographical note

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project
Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.


  • distributed multi-core quantum computing architectures
  • full-stack quantum computing systems
  • Quadratic Unconstrained Binary Optimization (QUBO)
  • quantum circuit mapping
  • quantum compilation


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