A generalized reconstruction model in circuit cutting and nonlocal-gate-based distributed quantum computation
Yi Sun, Changhua Zhu, Yuan Zhao, Guangwu Hou · New Journal of Physics · 2025
Abstract In the current noisy intermediate-scale quantum era, the limited number of high-fidelity qubits and restricted circuit depth pose significant challenges for large-scale quantum computation. Fortunately, distributed quantum computing (DQC) provides a feasible solution by dividing large quantum circuits into smaller subcircuits that can be executed on existing quantum processors. In this work, we propose a generalized model of circuit reconstruction (GMCR), which is capable of handling complex cutting patterns such as U-type structures to recover the output of the original circuit from the subcircuit results. In addition to the number of nonlocal gates and execution rounds, we introduce a new objective function in multi-objective simulated annealing (MOSA)-based cutting algorithm, the number of required SWAP operations in the subsequent mapping from logical qubits to physical qubits, which is used to satisfy the hardware connectivity constraints and to further decrease the complexity of quantum circuit compiling. We verified the GMCR model by cutting five circuits: encoding circuit for the Steane 7-qubit code, circuit of Shor’s algorithm, quantum supremacy circuit, quantum circuit of Bernstein–Vazirani algorithm, and circuit of approximate quantum Fourier transform. In the case of the Steane 7-qubit code, the number of reconstruction rounds was reduced from 337 to 156 under a fixed nonlocal gate count of two, while the number of SWAP operations was also reduced from 10 to 7 compared with the earlier MOSA-based algorithm. For the U-type subcircuits, using the GMCR model, the original results can be obtained, but cannot be obtained by the dynamic definition, approximate reconstruction algorithm, and fast reconstruction algorithm. This work plays an important role in implementing large-scale DQC, a typical application of future quantum Internet.