论文标题
$ \ MATHCAL {T} $ - 对称对旋转熔融和控制的对称性在合成旋转轨道中
Impact of $\mathcal{T}$-symmetry on spin decoherence and control in a synthetic spin-orbit field
论文作者
论文摘要
量子点中自旋量子置量的电控制依赖于自旋轨道耦合（SOC），这可能是基础晶体晶格或异质结构的内在固有的，或者外部通过，例如微型磁铁。在这里，我们表明，在时间逆转下，微型磁铁引入的固有SOC与合成SOC之间的关键区别是它们的对称性。具体而言，内在SOC的时间反向对称性（$ \ MATHCAL {T} $ - 对称性）不仅导致传统的范弗莱克（Van Vleck）取消以旋转放松的方式而闻名，而且还导致了SOC的最低序列，我们将其称为“ longitudinal Spin-Orbit Cancelcellation”。另一方面，来自微型磁铁的合成SOC打破了$ \ MATHCAL {T} $ - 对称性，因此消除了“ van Vleck取消”和“纵向自旋 - 轨道领域取消”。换句话说，旋转量子置量置量置量的有效字段$ \ \vecΩ$不再取决于量化磁场，并且允许使用$ \vecΩ$的纵向组件到SOC的第一阶。因此，与固有的SOC相比，自旋松弛和脱落是质化的。此外，可以优化基于$ \vecΩ$的电 - 偶极旋转共振的保真度，并具有基于自旋的量子计算中的潜在应用。
The electrical control of a spin qubit in a quantum dot relies on spin-orbit coupling (SOC), which could be either intrinsic to the underlying crystal lattice or heterostructure, or extrinsic via, for example, a micro-magnet. Here we show that a key difference between the intrinsic SOC and the synthetic SOC introduced by a micro-magnet is their symmetry under time reversal. Specifically, the time-reversal symmetry ($\mathcal{T}$-symmetry) of the intrinsic SOC leads to not only the traditional van Vleck cancellation known for spin relaxation, but also vanishing spin dephasing to the lowest order of SOC, which we term as "longitudinal spin-orbit field cancellation". On the other hand, the synthetic SOC from a micro-magnet breaks the $\mathcal{T}$-symmetry, therefore eliminates both the "van Vleck cancellation" and the "longitudinal spin-orbit field cancellation". In other words, the effective field $\vecΩ$ experienced by the spin qubit does not depend on the quantization magnetic field anymore, and a longitudinal component is allowed for $\vecΩ$ to the first order of SOC. Consequently, spin relaxation and dephasing are qualitatively modified compared with the case of the intrinsic SOC. Furthermore, the fidelity of electric-dipole spin resonance based on $\vecΩ$ could be optimized, with potential applications in spin-based quantum computing.
