IRIS: A Compiler for Distributed Quantum Systems
Abstract
Distributed Quantum Computers (DQCs) enable large system sizes by connecting smaller chips via photonic interconnects. DQCs use teleportation to relocate qubits and execute CNOTs between qubits on different chips. But, non-local CNOTs are 4.3-7.7× slower and 4× more error-prone than local CNOTs within a chip, which degrades program fidelities. Compilers group CNOTs with overlapping qubits into blocks and collectively optimize teleportations for each block. However, block-level scheduling suffers from two key drawbacks. First, they lack lookahead ability between blocks because they select the best schedule for a block before proceeding. So, they cannot assess the impact of a teleportation on future blocks. Our studies show that naively expanding the lookahead window to include subsequent blocks does not address the issue. Second, they do not schedule future block operations or teleportations they need unless preceding blocks are fully scheduled, introducing delay and latency overheads. We propose IRIS, a DQC compiler that addresses these limitations using two key insights: Utility-driven Lookahead With Multi-Candidate Block Scheduling (UMS) and EPR-Capacity-Aware Early Scheduling (EES). UMS schedules a block by considering only useful future blocks in its lookahead window. A future block has utility if it shares overlapping qubits with the current block being scheduled. UMS also maintains multiple schedules during compilation, allowing it to defer commitment to globally sub-optimal schedules early. EES enables IRIS to schedule future operations and their relocations early if EPR resources are available for teleportations. Our evaluations show that IRIS reduces teleportations by 34% on average and by up to 65%; and latency by 2× on average and by up to 2.9× compared to the state-of-the-art DQC compiler.
Related
- Distributed Phase Tags: A Locality-Preserving Realification Compiler for Misty-State Quantum Programs
- GadIR: A Spatial-Topology Preserving Compiler for Quantum Many-Body Systems Simulation
- QBX: A Compiler for 2-local Qubit Hamiltonian Simulation on Quantum Chiplets
- Retromorphic Testing of Quantum Compiler Passes
- Quantum Compiler Design for Fault-Tolerant Quantum Computing
BibTeX
@misc{yun2026iris,
title = {{IRIS: A Compiler for Distributed Quantum Systems}},
author = {Won Joon Yun and Dhilan Nag and Sneha Ballabh and Jiapeng Zhao and Eneet Kaur and Poulami Das},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2605.21795},
eprint = {2605.21795},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.21795},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - IRIS: A Compiler for Distributed Quantum Systems
AU - Won Joon Yun
AU - Dhilan Nag
AU - Sneha Ballabh
AU - Jiapeng Zhao
AU - Eneet Kaur
AU - Poulami Das
PY - 2026
DA - 2026/09/26
PB - arXiv
DO - 10.48550/arxiv.2605.21795
UR - https://arxiv.org/abs/2605.21795
AB - Distributed Quantum Computers (DQCs) enable large system sizes by connecting smaller chips via photonic interconnects. DQCs use teleportation to relocate qubits and execute CNOTs between qubits on different chips. But, non-local CNOTs are 4.3-7.7× slower and 4× more error-prone than local CNOTs within a chip, which degrades program fidelities. Compilers group CNOTs with overlapping qubits into blocks and collectively optimize teleportations for each block. However, block-level scheduling suffers from two key drawbacks. First, they lack lookahead ability between blocks because they select the best schedule for a block before proceeding. So, they cannot assess the impact of a teleportation on future blocks. Our studies show that naively expanding the lookahead window to include subsequent blocks does not address the issue. Second, they do not schedule future block operations or teleportations they need unless preceding blocks are fully scheduled, introducing delay and latency overheads. We propose IRIS, a DQC compiler that addresses these limitations using two key insights: Utility-driven Lookahead With Multi-Candidate Block Scheduling (UMS) and EPR-Capacity-Aware Early Scheduling (EES). UMS schedules a block by considering only useful future blocks in its lookahead window. A future block has utility if it shares overlapping qubits with the current block being scheduled. UMS also maintains multiple schedules during compilation, allowing it to defer commitment to globally sub-optimal schedules early. EES enables IRIS to schedule future operations and their relocations early if EPR resources are available for teleportations. Our evaluations show that IRIS reduces teleportations by 34% on average and by up to 65%; and latency by 2× on average and by up to 2.9× compared to the state-of-the-art DQC compiler.
ER -