Donor spins in silicon are some of the most promising qubits for upcoming solid-state quantum technologies. The nuclear spins of phosphorus donors in enriched silicon have among the longest coherence times of any solid-state system as well as simultaneous high fidelity qubit initialization, manipulation, and readout. Here we characterize the phosphorus in silicon system in the regime of “zero” magnetic field, where a singlet-triplet spin clock transition can be accessed, using laser spectroscopy and magnetic resonance methods. We show the system can be optically hyperpolarized and has $\sim 10$ s Hahn echo coherence times, even for applied static magnetic fields below Earth's field.

中文翻译：

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28硅中磷供体的零场光磁共振研究

硅的施主自旋是即将到来的固态量子技术中最有前途的量子位。富硅中磷供体的核自旋具有任何固态系统中最长的相干时间，以及同时的高保真量子位初始化，操纵和读出。在这里，我们用“零”磁场表征硅系统中的磷，其中可以使用激光光谱法和磁共振方法访问单重态-三重态自旋时钟转变。我们显示该系统可以是光学超极化的，并且具有$〜10$ 哈恩回波的相干时间，即使对于低于地球场的外加静磁场也是如此。