Department of Physics, Zhejiang University, Hangzhou, 310027, Zhejiang, China.
Department of Theoretical Physics and History of Science, The Basque Country University (EHU/UPV), PO Box 644, 48080, Bilbao, Spain.
Sci Rep. 2018 Jan 24;8(1):1471. doi: 10.1038/s41598-018-19977-9.
In spin-based nanosystems for quantum information processing, electron spin qubits are subject to decoherence due to their interactions with nuclear spin environments. In this paper, we present an exact master equation for a central spin-1/2 system in time-dependent external fields and coupled to a spin-half bath in terms of hyperfine interaction. The master equation provides a unified description for free and controlled dynamics of the central spin and is formally independent of the details and size of spin environments. Different from the previous approaches, the master equation remains exact even in the presence of external control fields. Using the parameters for realistic nanosystems with nonzero nuclear spins, such as GaAs, we investigate the Overhauser's effect on the decoherence dynamics of the central spin under different distributions of bath-spin frequencies and system-bath coupling strengths. Furthermore, we apply the leakage elimination operator, in a nonperturbative manner, to this system to suppress the decoherence induced by hyperfine interaction.
在基于自旋的量子信息处理纳米系统中，电子自旋量子比特由于与原子核自旋环境的相互作用而容易受到退相干的影响。在本文中，我们提出了一个关于在时变外场中与自旋半磁体耦合的中心自旋-1/2 系统的精确主方程，该方程基于超精细相互作用。该主方程为中心自旋的自由和受控动力学提供了统一的描述，并且与自旋环境的细节和大小无关。与以前的方法不同，即使存在外部控制场，主方程仍然是精确的。使用具有非零核自旋的实际纳米系统的参数，例如 GaAs，我们研究了在不同的磁体自旋分布和系统-磁体耦合强度下，奥弗豪瑟效应对中心自旋退相干动力学的影响。此外，我们以非微扰的方式应用泄漏消除算符来抑制超精细相互作用引起的退相干。
