Divide-et-impera Heuristic-based Randomized Search for the Qubit Routing Problem
Marco Baioletti, Fabrizio Fagiolo, Angelo Oddi, Riccardo Rasconi
TL;DR
This work tackles the Qubit Routing Problem (QRP) on NISQ architectures by introducing DIRSH, a divide-and-conquer search that partitions circuits into chunks and uses a stochastic, heuristic-guided gate selection moderated by a multi-armed bandit to adapt parameters. The method balances global search via restarts and local pruning, while updating the qubit assignment as swaps are added. Empirical results on RevLib circuits mapped to the 20-qubit IBMQ Tokyo topology show that DIRSH consistently outperforms LightSABRE variants across budgets $T ightarrow ig"{10,20,30,60}$ seconds, achieving shorter depths $de$ and fewer swaps $sw$. This demonstrates that chunk-based decomposition combined with bandit-driven heuristics is effective for quantum circuit routing on NISQ devices, with future directions including noise-aware cost models, better initial qubit allocations, and dynamic chunking.
Abstract
This paper introduces the DIRSH algorithm for the Qubit Routing Problem (QRP), using a heuristic-guided randomized divide-and-conquer strategy. The method splits the circuit into chunks and optimizes each one with a stochastic selection of gates and swaps. It balances global search, via restarts and adaptive tuning of bandit parameters with depth-sensitive local pruning. Tested on RevLib benchmarks mapped to the 20-qubit IBMQ Tokyo topology, DIRSH outperformed three LightSABRE variants across different time budgets, achieving shorter depths and fewer swaps. These results confirm that combining chunk-based decomposition with bandit-driven heuristics is effective for routing quantum circuits on NISQ devices.
