基于交换门的前瞻启发式量子线路映射算法

SWAP-Based Prospective Heuristic Quantum Circuit Mapping Algorithm

  • 摘要: 含噪声中规模量子硬件的耦合约束使得大多数量子算法通过插入附加量子门改变量子位映射,令量子算法直接运行在硬件上。为了降低量子线路的运行时间及提高量子线路的保真度,设计了一种基于交换门的前瞻双向启发式映射算法。首先,利用前瞻机制考虑前端层信息,提高了附加门数结果的稳定性。其次,设计搜索策略评估物理上近邻的候选交换门,降低交换门搜索空间的复杂度。最后,采用双向遍历全局考虑量子线路的门信息,得到更高质量的初始映射。此外,该算法适用于任意耦合量子硬件架构,同时具有线路深度和附加门数的选择能力。实验结果表明,相较于主流算法A*-based算法和SABRE算法,该文提出的SPBHA算法可减少约68%与34%的附加门数,线路执行时间缩短,保证了量子程序结果的可靠性。

     

    Abstract: The coupling constraint of noisy intermediate-scale quantum hardware makes most quantum algorithms change quantum bit mapping by inserting additional quantum gates, so that quantum algorithms run directly on the hardware. In order to reduce the quantum circuit running time and improve the quantum circuit fidelity, this paper designs a SWAP-based prospective heuristic quantum circuit mapping algorithm. First, the prospective mechanism is used to consider the front layer information, which improves the stability of the additional gate count results. Secondly, the search strategy is designed to evaluate the physically close candidate SWAP gates to reduce the search space complexity of SWAP gates. Finally, a bidirectional traversal is used to globally consider the gate information of quantum circuits to obtain higher quality initial mappings. The proposed algorithm is suitable for arbitrary coupled quantum hardware architecture, and has the ability to select circuit depth and additional gate number. The experimental results show that compared with the mainstream algorithms A*-based algorithm (Algorithm based on A* search) and SABRE algorithm (SWAP-based BidiREctional heuristic search algorithm), the SPBHA (SWAP-based Prospective Bidirectional Heuristic) algorithm proposed in this paper can reduce the number of additional gates by about 68% and 34%, shorten the circuit execution time, and ensure the reliability of the quantum program results.

     

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