Shows TopoLS Cuts Lattice Surgery Volume by 33% with Topological Transformations

Researchers are tackling the complex problem of compiling logical circuits for fault-tolerant quantum computation using surface codes, a crucial step towards building practical quantum computers. Junyu Zhou, Yuhao Liu, and Ethan Decker from the University of Pennsylvania, alongside Justin Kalloor and Mathias Weiden from UC Berkeley, and Kean Chen from the University of Pennsylvania, introduce TopoLS, a novel topological compiler that significantly improves this process. Their work combines ZX-diagram optimisations with Monte Carlo tree search, enabling scalable exploration of lattice surgery structures and consistently reducing the resources needed for quantum error correction. Evaluations demonstrate TopoLS achieves an average 33% reduction in space-time volume compared to existing compilers, offering a practical and scalable solution where optimal, but computationally expensive, methods fail.

ZX-diagram optimisation and Monte Carlo search reduce quantum compilation costs significantly

Scientists have developed TopoLS, a novel topological compiler that significantly reduces the resource overhead associated with fault-tolerant quantum computing using surface codes. The research team achieved a 33% average reduction in space-time volume compared to existing heuristic-based compilers, while maintaining linear compilation time scaling.
This breakthrough stems from a unique approach that combines ZX-diagram optimizations with Monte Carlo tree search, guided by operation placements and topology-aware circuit partitioning. TopoLS enables scalable exploration of lattice surgery structures by leveraging the topological properties inherent in quantum computation.

The study unveils a method for transforming quantum circuits into ZX diagrams, simplifying them through spider fusion and layer-based slicing to directly capture merge-split operations. This topological representation allows for reductions in space-time volume unattainable with traditional gate-based models.

Researchers then applied a 3D diagram layout optimization using Monte Carlo tree search, guiding the compilation towards layouts with reduced volume and efficient qubit embeddings. Furthermore, the work establishes a scalable solution through topology-aware circuit partitioning, dynamically dividing circuits based on spider connectivity.

By limiting operations per layer, the team made the embedding problem tractable while preserving topological advantages. Evaluations across various benchmark algorithms and hardware architectures demonstrate consistent performance gains, ranging from 4% to 87% reduction in space-time volume. TopoLS efficiently compiles circuits up to 100 qubits, offering a substantial improvement over SAT-solver-based compilers which become intractable for larger circuits.

This research opens new avenues for building large-scale, fault-tolerant quantum computers and realizing significant quantum algorithms. The ability to minimize space-time volume is essential for reducing overhead and improving the efficiency of quantum computation, paving the way for more practical and powerful quantum devices.

ZX-diagram compilation and Monte Carlo Tree Search for optimised lattice surgery offer a promising approach

Scientists developed TopoLS, a topological compiler designed to minimise space-time volume in fault-tolerant quantum computation using surface codes. The research team compiled logical circuits into lattice-surgery instructions, leveraging ZX-diagram optimisation combined with Monte Carlo Tree Search (MCTS).

This approach enables scalable exploration of lattice surgery structures and consistently reduces resource overhead during quantum operations. Initially, quantum circuits were transformed into ZX diagrams, facilitating simplification through spider fusion techniques. These diagrams were then layer-sliced based on topological connections, directly capturing merge, split operations and enabling reductions in space, time volume unattainable with conventional gate-based models.

The study pioneered a 3D diagram layout optimisation using MCTS, employing the ZX diagram enriched with layer-slicing information to search for efficient embeddings in 3D space. Experiments harnessed topology-aware circuit partitioning to enhance scalability, dynamically partitioning circuits based on spider connectivity.

This limited the number of operations per layer, making the embedding problem tractable while preserving topological advantages. Evaluations of benchmark algorithms across multiple architectures demonstrated that TopoLS achieves an average 33% reduction in space, time volume compared to prior heuristic-based compilers.

Compared to a SAT-solver-based compiler, which becomes intractable for larger circuits, TopoLS offers an effective and scalable solution for lattice-surgery compilation. The system delivers improvements ranging from 4% to 87% across benchmarks, maintaining similar gains across grid layouts of varying shapes and sizes, with reductions of 20% to 26%. TopoLS efficiently compiles circuits up to 100 qubits, exhibiting linear growth in compilation time.

TopoLS achieves substantial reductions in quantum compilation resource overhead via ZX-calculus and Monte Carlo Tree Search, demonstrating improved performance on standard benchmarks

Scientists have developed TopoLS, a novel topological compiler for fault-tolerant quantum computation using surface codes. The research demonstrates a 33% average reduction in space-time volume compared to existing heuristic-based compilers. Experiments measured this reduction across various benchmark algorithms and multiple architectures, confirming TopoLS’s efficiency.

This breakthrough delivers a scalable solution for lattice-surgery compilation, addressing limitations of prior methods. The team integrated ZX-calculus representation with Monte Carlo Tree Search (MCTS) to optimise lattice surgery structures. ZX diagrams preserve the high-level topological structure of quantum programs, while MCTS efficiently searches for optimal scheduling and placement of merge-split operations.

Measurements confirm that this approach enables scalable exploration of lattice surgery structures and consistently reduces resource overhead. The work details how quantum circuits are transformed into ZX diagrams and simplified through spider fusion. Results demonstrate that slicing diagrams into layers based on topological connections directly captures merge-split operations, leading to reductions in space-time volume.

MCTS then searches for efficient embeddings of these diagrams in 3D space, guiding compilation towards layouts with minimal volume. Topology-aware circuit partitioning further enhances scalability by dynamically partitioning circuits based on spider connectivity. Tests prove that TopoLS maintains linear compilation time scaling, unlike SAT-solver-based compilers which become intractable for larger circuits.

The breakthrough achieves an average 33% reduction in space-time volume, a critical metric for evaluating the efficiency of fault-tolerant quantum computation. Data shows that TopoLS offers an effective and scalable solution, surpassing the limitations of both heuristic and formal compilation methods. This research paves the way for more efficient implementation of logical operations in quantum computers, potentially accelerating the development of practical quantum algorithms.

TopoLS achieves substantial space-time volume reduction in 2D rotated surface code compilation, improving resource efficiency

Scientists have developed TopoLS, a topological compiler designed to optimise lattice surgery for fault-tolerant quantum computing. This new approach combines ZX-diagram optimisations with Monte Carlo tree search, guided by strategic operation placement and topology-aware circuit partitioning, to minimise space-time volume.

Evaluations using benchmark algorithms and various architectures demonstrate that TopoLS reduces space-time volume by an average of 33% compared to existing heuristic compilers. TopoLS offers a scalable solution to lattice-surgery compilation, maintaining linear compilation time even as circuit complexity increases.

Unlike SAT-solver-based compilers, which become impractical for larger circuits, TopoLS consistently delivers effective results. The authors acknowledge that their work currently focuses on the 2D rotated surface code architecture, representing a limitation in broader applicability. Future research could explore extending TopoLS to other quantum error correction codes and investigating more advanced circuit partitioning strategies to further enhance performance and scalability. These findings represent a significant step towards practical, resource-efficient fault-tolerant quantum computation.