Circuit Partitioning and Transmission Cost Optimization in Distributed Quantum Computing

Given the limitations on the number of qubits in current NISQ devices, the implementation of large-scale quantum algorithms on such devices is challenging, prompting research into distributed quantum computing. This paper focuses on the issue of excessive communication complexity in distributed quantum computing oriented towards quantum circuits. To reduce the number of quantum state transmissions, i.e., the transmission cost, in distributed quantum circuits, a circuit partitioning method based on the QUBO model is proposed, coupled with the lookahead method for transmission cost optimization. Initially, the problem of distributed quantum circuit partitioning is transformed into a graph minimum cut problem. The QUBO model, which can be accelerated by quantum algorithms, is introduced to minimize the number of quantum gates between QPUs and the transmission cost. Subsequently, the dynamic lookahead strategy for the selection of transmission qubits is proposed to optimize the transmission cost in distributed quantum circuits. Finally, through numerical simulations, the impact of different circuit partitioning indicators on the transmission cost is explored, and the proposed method is evaluated on benchmark circuits. Experimental results demonstrate that the transmission cost optimized through the method proposed in this paper is significantly reduced compared with current methods for optimizing transmission cost, achieving noticeable improvements across different numbers of partitions.