Class Synthesizer Reduces Quantum Circuit Latency by 100% with 2.10% Operation Increase

Layout synthesis represents a fundamental challenge in designing efficient quantum computers, yet current methods often prioritise minimising circuit depth without fully accounting for the crucial role of classical processing. Yu Chen, Yilun Zhao, and Bing Li, alongside colleagues at their institutions, now present a new approach, called CLASS, that tackles this limitation by focusing on the layout of control systems within dynamic quantum circuits. This controller-centric layout synthesizer significantly reduces delays between control operations, a critical factor in achieving faster and more reliable quantum computation. Evaluations demonstrate that CLASS achieves up to a 100% reduction in latency, with a minimal increase of only 2. 10% in the overall number of operations required, representing a substantial advance in the field of quantum computer design.

Traditional LSQC studies primarily focus on optimising for reduced circuit depth, adopting a device-centric design methodology. However, these approaches overlook the impact of classical processing and communication time, proving insufficient for Dynamic Quantum Circuits (DQC). To address this limitation, researchers introduce CLASS, a controller-centric layout synthesiser designed to reduce inter-controller communication latency in a distributed control system. It consists of a two-stage framework featuring hypergraph-based modelling and a heuristic-based graph partitioning algorithm.

Layout Synthesis Minimising Controller Communication Latency

Scientists developed CLASS, a controller-centric layout synthesizer, to address limitations in existing quantum circuit design tools that overlook the impact of classical processing and communication time, particularly for dynamic quantum circuits. The research team recognised that traditional layout synthesis focuses on minimising on-device operation latency, an approach insufficient for accurately modelling the total execution time of dynamic circuits which involve frequent mid-circuit measurements and feedforward operations. To overcome this, they engineered a methodology that prioritises minimising inter-controller communication latency in distributed control systems, a critical performance bottleneck as quantum systems scale. The core of CLASS involves reformulating the layout synthesis problem as a hypergraph partitioning task, allowing for a concise and modular algorithmic framework.

This approach models the quantum circuit as a hypergraph, where qubits and operations are represented as nodes and hyperedges, enabling efficient analysis of qubit connectivity and control dependencies. The team then developed a heuristic-based graph partitioning algorithm to assign logical qubits to controllers, aiming to minimise communication overhead for each measurement-feedforward operation. Specifically, the algorithm seeks to map qubits involved in these operations to a single controller whenever possible, eliminating the need for inter-controller communication and significantly reducing latency. Evaluations demonstrate that CLASS effectively reduces communication latency by up to 100%, while incurring only a 2.

10% average increase in the number of additional operations. This improvement stems from the system’s ability to optimise qubit placement based on control dependencies, rather than solely focusing on minimising the number of swap gates. The research team validated the approach through extensive simulations, demonstrating its effectiveness in reducing overall program execution time for dynamic quantum circuits and paving the way for more efficient and scalable quantum computing systems.

Controller-Centric Layout Minimizes Quantum Latency

Scientists have developed CLASS, a novel layout synthesizer designed to optimize performance in distributed quantum computing systems. This work addresses a critical bottleneck in dynamic quantum circuits, the latency introduced by communication between quantum control processors, or QCPs. The team’s research demonstrates that minimizing inter-controller latency is paramount for executing complex quantum algorithms efficiently. Through detailed analysis, researchers identified instruction processing time within quantum control systems as the dominant factor affecting overall program execution time, revealing the limitations of approaches that focus solely on on-device operation latency.

CLASS reformulates the layout synthesis problem as a hypergraph partitioning task, creating a concise and modular algorithmic framework readily integrated into existing quantum design pipelines. Evaluations across a variety of dynamic quantum circuit benchmarks demonstrate CLASS’s effectiveness, achieving an average 48. 45% reduction in inter-controller communication hops compared to existing synthesizers, with only a 2. 10% average increase in additional operations. This significant reduction in communication overhead directly translates to faster execution times and improved fidelity for complex quantum algorithms. The implementation is openly available, facilitating further research and development in the field, paving the way for larger, more complex quantum computations.

Controller-Centric Synthesis Minimizes Quantum Communication Latency

This work presents a novel approach to layout synthesis for dynamic quantum circuits, addressing a critical limitation in existing design tools that overlook the impact of communication delays between controllers. Researchers developed CLASS, a controller-centric synthesizer that models the problem as a hypergraph and employs a heuristic-based graph partitioning algorithm to minimize inter-controller latency. Evaluations demonstrate that CLASS effectively reduces communication delays by up to 100%, achieving this improvement with a modest increase of approximately 2% in the number of required operations. The significance of this achievement lies in its potential to improve the performance of complex quantum computations, where communication overhead can significantly limit scalability.