标题： 对耦合到一维周期驱动自旋链的量子比特的过量能量和退相干因子的研究 显示英文标题

标题： A study of excess energy and decoherence factor of a qubit coupled to a one dimensional periodically driven spin chain

摘要： 我们采用一个中心自旋模型（CSM），该模型由一维环境Ising自旋链和一个与环境所有自旋全局连接的单个量子比特组成，使用Floquet技术研究环境的过剩能量（EE）以及与量子比特相关的对数退相干因子，即每单位面积的动力学保真度敏感度（DFSS），在环境横向场项周期性驱动穿过其临界点时的情况。 与量子比特（处于纯态）耦合的横向场自旋链会产生两组EE，对应于两种类型的Floquet算子。 在弱耦合极限下，我们推导出经过无限多个驱动周期后的DFSS的近似表达式，该表达式可以成功估计数值获得的DFSS的低频和中频行为。 我们的主要重点是通过合理的分析论证，分析研究环境耦合强度对EEs和DFSS的影响，并将DFSS的行为与EEs作为频率函数的关系联系起来。 我们明确表明，DFSS的低频拍频模式是两个频率的结果，导致两个分支的EEs中的振荡，这些振荡依赖于耦合强度。 在中频区域，DFSS中观察到的凹陷结构可以通过在那些依赖于耦合参数的频率处EEs的共振峰来解释；EEs和DFSS的高频饱和值也通过耦合强度相互关联。 显示英文摘要

摘要： We take a central spin model (CSM), consisting of a one dimensional environmental Ising spin chain and a single qubit connected globally to all the spins of the environment, to study numerically the excess energy (EE) of the environment and the logarithm of decoherence factor namely, dynamical fidelity susceptibility per site (DFSS), associated with the qubit under a periodic driving of the transverse field term of environment across its critical point using the Floquet technique. The coupling to the qubit, prepared in a pure state, with the transverse field of the spin chain yields two sets of EE corresponding to the two species of Floquet operators. In the limit of weak coupling, we derive an approximated expression of DFSS after an infinite number of driving period which can successfully estimate the low and intermediate frequency behavior of numerically obtained DFSS. Our main focus is to analytically investigate the effect of system-environment coupling strength on the EEs and DFSS and relate the behavior of DFSS to EEs as a function of frequency by plausible analytical arguments. We explicitly show that the low-frequency beating like pattern of DFSS is an outcome of two frequencies, causing the oscillations in the two branches of EEs, that are dependent on the coupling strength. In the intermediate frequency regime, dip structure observed in DFSS can be justified by the resonance peaks of EEs at those coupling parameter dependent frequencies; high frequency saturation value of EEs and DFSS are also connected to each other by the coupling strength.