论文标题
多物种离子陷阱量子计算机中Qubit的相干旋转
Coherent rotations of qubits within a multi-species ion-trap quantum computer
论文作者
论文摘要
我们描述，实现和实验研究一种使离子链的物理旋转的方法，被困在分段的表面Paul陷阱中，作为大型量子计算序列的基础。通过在球形谐波电位方面对电极电压进行参数来实现捕获电势的控制。通过优化时间依赖性离子位置和运动频率，可以在数值上获得启用晶体旋转的电压序列，并考虑到电气过滤器在我们的设置中的影响。我们通过将序列扩展为傅立叶组件，并通过机器学习方法优化所得参数来最大程度地减少旋转诱导的加热。优化序列旋转$^{40} $ ca $^+$ - $^{40} $ ca $^+$ crystals，轴向加热速率为$δ\ bar {n} _ {com} = 0.6^{（+3）} _ {（+3）} _ {（ - 2）} $和$δ\ bar {n} _} _}拉伸模式，在1.24和2.15 MHz的模式频率下。量子相干性损失为0.2（2）$ \％$每旋转。我们还研究了混合物种晶体的旋转（$^{40} $ ca $^+$ - $ - $^{88} $ sr $^+$）并实现了Unity成功率。
We describe, realize, and experimentally investigate a method to perform physical rotations of ion chains, trapped in a segmented surface Paul trap, as a building block for large scale quantum computational sequences. Control of trapping potentials is achieved by parametrizing electrode voltages in terms of spherical harmonic potentials. Voltage sequences that enable crystal rotations are numerically obtained by optimizing time-dependent ion positions and motional frequencies, taking into account the effect of electrical filters in our set-up. We minimize rotation-induced heating by expanding the sequences into Fourier components, and optimizing the resulting parameters with a machine-learning approach. Optimized sequences rotate $^{40}$Ca$^+$ - $^{40}$Ca$^+$ crystals with axial heating rates of $Δ\bar{n}_{com}=0.6^{(+3)}_{(-2)}$ and $Δ\bar{n}_{str}=3.9(5)$ phonons per rotation for the common and stretch modes, at mode frequencies of 1.24 and 2.15 MHz. Qubit coherence loss is 0.2(2)$\%$ per rotation. We also investigate rotations of mixed species crystals ($^{40}$Ca$^+$ - $^{88}$Sr$^+$) and achieve unity success rate.
