Spins in gate-defined silicon quantum dots are promising candidates for implementing large-scale quantum computing. To read the spin state of these qubits, the mechanism that has provided the highest fidelity is spin-to-charge conversion via singlet-triplet spin blockade, which can be detected in situ using gate-based dispersive sensing. In systems with a complex energy spectrum, like silicon quantum dots, accurately identifying when singlet-triplet blockade occurs is hence of major importance for scalable qubit readout. In this work, we present a description of spin-blockade physics in a tunnel-coupled silicon double quantum dot defined in the corners of a split-gate transistor. Using gate-based magnetospectroscopy, we report successive steps of spin blockade and spin-blockade lifting involving spin states with total spin angular momentum up to $S=3$. More particularly, we report the formation of a hybridized spin-quintet state and show triplet-quintet and quintet-septet spin blockade, enabling studies of the quintet relaxation dynamics from which we find $T_1\sim 4\mu \mathrm{s}$. Finally, we develop a quantum capacitance model that can be applied generally to reconstruct the energy spectrum of a double quantum dot, including the spin-dependent tunnel couplings and the energy splitting between different spin manifolds. Our results allow for the possibility of using Si complementary metal-oxide-semiconductor quantum dots as a tunable platform for studying high-spin systems.

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硅双量子点中的自旋五重奏：自旋封锁和弛豫

栅极定义的硅量子点中的自旋是实现大规模量子计算的有希望的候选者。为了读取这些量子位的自旋状态，提供最高保真度的机制是通过单重态-三重态自旋封锁的自旋至电荷转换，可以原位检测使用基于门的色散传感。因此，在具有复杂能谱的系统（如硅量子点）中，准确确定何时发生单重态-三重态阻塞对于可伸缩的量子位读数至关重要。在这项工作中，我们描述了在分裂栅晶体管的角部定义的隧道耦合硅双量子点中的自旋封锁物理。使用基于门的磁波谱仪，我们报告了自旋阻滞和自旋阻滞提升的连续步骤，涉及自旋态，总自旋角动量高达$\mathrm{小号}=3$。更具体地讲，我们报告了混合的自旋五重态的形成，并显示了三重五重态和五重九态的自旋封锁，从而使我们能够研究五重态松弛动力学。${Ť}_{\mathrm{1个}}〜4\mu \mathrm{s}$。最后，我们开发了一种量子电容模型，该模型可普遍用于重构双量子点的能谱，包括自旋相关的隧道耦合以及不同自旋流形之间的能量分裂。我们的结果允许使用硅互补金属氧化物半导体量子点作为研究高自旋系统的可调平台的可能性。