发表机构
Quaid-i-Azam University; National Centre for Physics（奎达伊阿扎姆大学; 国家物理中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文研究两量子比特与共同玻色子库的纠缠动力学，发现初始关联加速纠缠突然死亡，且对称π脉冲序列可将纠缠寿命延长近七倍。
AI 中文摘要
我们研究了通过纯退相相互作用耦合到共同玻色子库的两个量子比特的精确纠缠动力学。我们探究当量子比特与库在量子比特态制备之前已经共享关联时，该动力学如何变化。在这种情况下，系统与库首先长时间相互作用并达到联合平衡态。仅在此之后，量子比特对通过局域测量被投影到期望状态。对于欧姆谱密度，我们获得了精确的约化双量子比特动力学。利用Wootters并发度，我们表明初始关联总是相对于因子化情形加速纠缠突然死亡，并且该差距在弱至中等耦合区域随耦合强度二次增长。最后，我们表明对两个量子比特施加的对称周期π脉冲序列将纠缠寿命延长至接近所研究脉冲数范围内的七倍。
英文摘要
We study the exact entanglement dynamics of two qubits coupled to a common bosonic reservoir through a pure dephasing interaction. We ask how this dynamics changes when the qubits and the reservoir already share correlations before the qubit state is prepared. In that case the system and reservoir first interact for a long time and settle into a joint equilibrium state. Only afterward is the qubit pair projected onto the desired state by a local measurement. For an Ohmic spectral density we obtain the exact reduced two qubit dynamics. Using the Wootters concurrence we show that initial correlations always speed up entanglement sudden death relative to the factorized case, and that this gap grows quadratically with the coupling strength in the weak-to-moderate coupling regime. Finally we show that a symmetric sequence of periodic π pulses applied to both qubits extends the entanglement lifetime close to a factor of seven over the range of pulse numbers studied.
Comments10 pages, 5 figures
