标题： 提出的五电子电荷四极子量子比特 显示英文标题

标题： Proposed Five-Electron Charge Quadrupole Qubit

摘要： 一个电荷量子比特通过其偶极矩与环境电场涨落耦合，导致快速退相干。 我们提出了p轨道(pO)量子比特，它由五个电子的硅量子点的单个电子、类似p的价态形成，通过四极矩与电荷噪声耦合。 我们证明pO量子比特在品质因数、门速度、读出和尺寸方面具有显著优势。 我们使用一种经验性的偶极子两能级涨落电荷噪声模型来估计一个$T_2^* \sim 80$ ns。 结合约10 GHz的拉比频率，相对于最先进的半导体自旋量子比特，量子比特的品质因数有望提高一个数量级。 pO量子比特通过调节量子点的偏心率实现全电气控制。 我们还展示了如何通过$1/r^5$四极矩-四极矩相互作用执行双量子比特门。 我们在最大允许带宽为10 GHz和脉冲时间为1 ns的条件下，使用基于梯度上升的控制脉冲优化方法找到一个通用门集。 显示英文摘要

摘要： A charge qubit couples to environmental electric field fluctuations through its dipole moment, resulting in fast decoherence. We propose the p orbital (pO) qubit, formed by the single electron, p-like valence states of a five-electron Si quantum dot, which couples to charge noise through the quadrupole moment. We demonstrate that the pO qubit offers distinct advantages in quality factor, gate speed, readout and size. We use a phenomenological, dipole two-level-fluctuator charge noise model to estimate a $T_2^* \sim 80$ ns. In conjunction with Rabi frequencies of order 10 GHz, an order of magnitude improvement in qubit quality factor is expected relative to state-of-the-art semiconductor spin qubits. The pO qubit features all-electrical control via modulating the dot's eccentricity. We also show how to perform two-qubit gates via the $1/r^5$ quadrupole-quadrupole interaction. We find a universal gate set using gradient ascent based control pulse optimization, subject to 10 GHz maximum allowable bandwidth and 1 ns pulse times.