论文标题
在机械振荡器中编码的逻辑Qubit的非扰动泄漏消除
Nonperturbative leakage elimination for a logical qubit encoded in a mechanical oscillator
论文作者
论文摘要
在通用量子计算的实现中，连续变量（CV）系统正在引起越来越多的关注。最近的一些实验表明，使用CV系统将值编码为捕获的离子机械振荡器并执行逻辑门的可行性[Nature 566，513-517（2019）]。重要的下一步是保护编码的量子脉冲免受量子反应的影响，例如，由于机械振荡器与其环境之间的相互作用而引起的运动反应性。在这里，我们提出了一种抑制单模谐波振荡器的量子反应，用于通过引入专门为此目的设计的非扰动泄漏消除操作员（LEO）来编码Qubits。值得注意的是，我们的非扰动狮子座可用于分析无近似值的精确运动方程。它还使我们能够证明这些LEO的有效性仅取决于时间域中的脉冲序列的积分，而当适当选择时间段时，脉冲形状的细节并没有显着差异。该控制方法可以在任意温度和任意系统轴耦合强度下应用于系统，这使其对于一般的开放量子系统非常有用。
Continuous-variable (CV) systems are attracting increasing attention in the realization of universal quantum computation. Several recent experiments have shown the feasibility of using CV systems to, e.g., encode a qubit into a trapped-ion mechanical oscillator and perform logic gates [Nature 566, 513-517 (2019)]. The essential next step is to protect the encoded qubit from quantum decoherence, e.g., the motional decoherence due to the interaction between a mechanical oscillator and its environment. Here we propose a scheme to suppress quantum decoherence of a single-mode harmonic oscillator used to encode qubits by introducing a nonperturbative leakage elimination operator (LEO) specifically designed for this purpose. Remarkably, our nonperturbative LEO can be used to analytically derive exact equations of motion without approximations. It also allows us to prove that the effectiveness of these LEOs only depends on the integral of the pulse sequence in the time domain, while details of the pulse shape does not make a significant difference when the time period is chosen appropriately. This control method can be applied to a system at an arbitrary temperature and arbitrary system-bath coupling strength which makes it extremely useful for general open quantum systems.
