发表机构
Xi’an Jiaotong University; Shenzhen International Quantum Academy; Southern University of Science and Technology（西安交通大学; 深圳国际量子学院; 南方科技大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
提出全微波方案实现单步多量子比特门，利用交叉共振驱动增强相互作用，无需可调耦合器，实现高保真度（>99.9%）三量子比特门，并验证五量子比特可扩展性，为降低稳定子操作电路深度提供硬件高效策略。
AI 中文摘要
实现高保真度的多量子比特门对于降低近期量子处理器和容错架构中的电路深度至关重要。然而，实现多量子比特相互作用和纠缠仍然是限制多量子比特门实现的关键挑战。在此，我们提出了一种全微波方案，以实现包含n个控制量子比特和m个目标量子比特的单步多量子比特门，该方案专为频率可调的超导transmon网络量身定制。通过利用交叉共振（CR）驱动，该方法诱导出有效的两体ZX相互作用，其强度显著强于传统共振区域中实现的相互作用，从而无需可调耦合器。系统的有效哈密顿量通过使用四帧旋转和严格的块对角化方法解析推导得出。这些结合的理论方法有助于识别最佳参数区域，该区域同时增强所需的目标耦合并抑制寄生高阶项，如ZXX相互作用。通过数值模拟和基于梯度的脉冲形状优化，我们展示了在60纳秒门持续时间内实现保真度超过99.9%的三量子比特门。此外，我们通过将优化扩展到五量子比特CXXXX架构来评估该框架的基本可扩展性，证实了多目标驱动方案的物理可行性。由于这些多量子比特操作自然地模拟了稳定子测量，该架构提供了一种硬件高效的策略，通过用单步多量子比特门替换顺序的两量子比特门分解来降低稳定子型操作的电路深度。
英文摘要
Implementing high-fidelity multiqubit gates is critical for reducing circuit depth in near-term quantum processors and fault-tolerant architectures. However, realizing multiqubit interactions and entanglement remains a critical challenge that limits the implementation of multiqubit gates. Here we propose an all-microwave scheme to realize single-step multiqubit gates incorporating n control and m target qubits, tailored for frequency-tunable superconducting transmon networks. By leveraging cross-resonance (CR) drives, this approach induces effective two-body ZX interactions that are significantly stronger than those achieved in conventional resonant regimes, circumventing the need for tunable couplers. The system's effective Hamiltonian is analytically derived using both quad frame rotation and rigorous block diagonalization. These combined theoretical methods facilitate the identification of optimal parameter regimes that simultaneously enhance desired target couplings and suppress parasitic higher-order terms, such as ZXX interactions. Through numerical simulations and gradient-based pulse-shape optimization, we demonstrate three-qubit gates achieving fidelities exceeding 99.9% within a 60 ns gate duration. Furthermore, we evaluate the fundamental scalability of this framework by extending the optimization to a five-qubit CXXXX architecture, confirming the physical viability of the multi-target driving scheme. Because these multiqubit operations naturally emulate stabilizer measurements, this architecture provides a hardware-efficient strategy for reducing the circuit depth of stabilizer-type operations by replacing sequential two-qubit gate decompositions with single-step multiqubit gates.
