利用弱耦合通量量子比特的玻色量子控制
Bosonic quantum control with a weakly coupled fluxonium qubit
- Université de Sherbrooke（舍布鲁克大学）
- Massachusetts Institute of Technology（麻省理工学院）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究针对玻色量子控制中辅助量子比特比特翻转的误差问题，以抗比特翻转通量量子比特为控制量子比特，在单模谐振器-通量量子比特器件中实现了保真度超99.9%的ECD门，还开发了相关模拟技术并提出改进的ECD序列。
AI中文摘要：
回波条件位移（Echoed Conditional Displacement, ECD）门是量子控制谐振子模式的基本构建模块。然而，辅助量子比特的比特翻转仍是这类玻色控制的主要误差机制。本工作对作为控制量子比特的抗比特翻转通量量子比特开展数值案例研究，在单模谐振器-通量量子比特器件中数值实现ECD门，证明其保真度可超过99.9%。我们结合半经典轨迹与主方程模拟，系统研究谐振器动力学，数值揭示谐振器强驱动区域中色散位移的渐近饱和现象。我们开发了一种高效技术，利用半经典公式数值模拟谐振器的强驱动区域，该公式将色散展开的完整微扰级数映射为逐阶频率偏移，为谐振器提供了紧凑的多项式描述，直观且在整个色散区域内有效。此外，我们提出了一种改进的ECD序列，可考虑光子损耗和谐振器轨迹上的杂散非线性项的影响。
英文摘要：
Echoed Conditional Displacement (ECD) gates constitute a fundamental building block for quantum control of harmonic oscillator modes. However, bit-flips of the auxiliary qubit remain a dominant error mechanism for this kind of bosonic control. In this work, we present a numerical case study of a bit-flip protected fluxonium operating as the control qubit and numerically implement ECD gates in a single-mode resonator-fluxonium device, demonstrating that fidelities exceeding 99.9% are possible. We systematically investigate the resonator dynamics using a combination of semiclassical trajectories and master equation simulations, numerically revealing asymptotic saturation of the dispersive shift in the strongly driven regime of the resonator. We develop an efficient technique to numerically simulate the strongly driven regime of the resonator using a semiclassical formulation that maps the full perturbation series in the dispersive expansion as order-by-order frequency shifts. This provides a compact polynomial description of the resonator which is intuitive and remains valid throughout the dispersive regime. Furthermore, we propose an improved ECD sequence that accounts for the effects of photon loss and spurious nonlinear terms on resonator trajectories.
