一种具有容错控制保真度的可寻址量子点量子比特
An addressable quantum dot qubit with fault-tolerant control fidelity
摘要：
最近，基于自旋的量子计算取得了令人兴奋的进展，量子位是利用金刚石中的氮空位（N-V）中心和硅中的磷原子实现的，包括证明碳和硅的无自旋同位素的存在使长相干时间成为可能。然而，尽管单原子纳米技术前景看好，但在耦合这些量子位并单独解决它们方面仍然存在重大挑战。相反，光刻定义的量子点具有可以精确设计的交换耦合，但是与噪声的强耦合严重限制了它们的失相时间和控制精度。在这里，我们结合了两个自旋量子位方案的最佳方面，并展示了一个门可寻址的量子点量子位在同位素工程硅与99.6%的控制保真度，通过基于Clifford的随机基准测试和所需的容错量子计算一致。与其他量子点量子位相比，该量子位具有数量级改进的相干时间，其中T_2* = 120 μ s和T_2 = 28 ms。通过对电子g* 因子的栅极电压调谐，我们可以使电子自旋共振（ESR）频率Stark偏移超过2.4 kHz ESR线宽的3000倍，提供了一条通向与现有制造技术兼容的可寻址高保真量子位的大规模阵列的直接路径。
英文摘要：
Exciting progress towards spin-based quantum computing has recently been made with qubits realized using nitrogen-vacancy (N-V) centers in diamond and phosphorus atoms in silicon, including the demonstration of long coherence times made possible by the presence of spin-free isotopes of carbon and silicon. However, despite promising single-atom nanotechnologies, there remain substantial challenges in coupling such qubits and addressing them individually. Conversely, lithographically defined quantum dots have an exchange coupling that can be precisely engineered, but strong coupling to noise has severely limited their dephasing times and control fidelities. Here we combine the best aspects of both spin qubit schemes and demonstrate a gate-addressable quantum dot qubit in isotopically engineered silicon with a control fidelity of 99.6%, obtained via Clifford based randomized benchmarking and consistent with that required for fault-tolerant quantum computing. This qubit has orders of magnitude improved coherence times compared with other quantum dot qubits, with T_2* = 120 mus and T_2 = 28 ms. By gate-voltage tuning of the electron g*-factor, we can Stark shift the electron spin resonance (ESR) frequency by more than 3000 times the 2.4 kHz ESR linewidth, providing a direct path to large-scale arrays of addressable high-fidelity qubits that are compatible with existing manufacturing technologies.
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