Entanglement robustness to excitonic spin precession in a quantum dot
Entanglement robustness to excitonic spin precession in a quantum dot
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DOI：
10.1103/physrevb.102.045304
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发表时间：
2020-01
影响因子：
3.7
通讯作者：
S. Bounouar;G. Rein;K. Barkemeyer;Julian Schleibner;Peter Schnauber;M. Gschrey;J. Schulze;A. Strittmatter;S. Rodt;A. Knorr;A. Carmele;S. Reitzenstein
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文献类型：
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作者：
S. Bounouar;G. Rein;K. Barkemeyer;Julian Schleibner;Peter Schnauber;M. Gschrey;J. Schulze;A. Strittmatter;S. Rodt;A. Knorr;A. Carmele;S. Reitzenstein
半导体量子点是产生偏振纠缠光子对的理想材料。研究了一类具有不同激子精细结构分裂（FSS）的量子点中的激子自旋进动（Flip-flop）及其对激子-双激子辐射级联产生的光子纠缠的影响.我们的结果表明，相干过程离开量子点的时间后选择纠缠与有限的FSS不受影响，而改变系统的本征态。触发器的进动是通过量子层析成像观察到的，通过异常振荡的重合在直线基础。一个理论模型的构建与包括激子的触发率，并与双光子量子断层扫描测量表现出自旋触发机制的量子点进行比较。的理论模型的概括允许估计的纠缠度作为一个功能的FSS和自旋翻转率。对于一个有限的时间分辨率，负被发现是振荡的FSS和自旋翻转率。这种振荡行为消失完美的时间分辨率和最大的纠缠，尽管触发器的过程中检索。
A semiconductor quantum dot (QD) is an attractive resource to generate polarization-entangled photon pairs. We study the excitonic spin precession (flip-flop) in a family of QDs with different excitonic fine-structure splitting (FSS) and its impact on the entanglement of photons generated from the excitonic-biexcitonic radiative cascade. Our results reveal that coherent processes leave the time post-selected entanglement of QDs with finite FSS unaffected while changing the eigenstates of the system. The flip-flop's precession is observed via quantum tomography through anomalous oscillations of the coincidences in the rectilinear basis. A theoretical model is constructed with the inclusion of an excitonic flip-flop rate and is compared with a two-photon quantum tomography measurement on a QD exhibiting the spin flip-flop mechanism. A generalization of the theoretical model allows estimating the degree of entanglement as a function of the FSS and the spin-flip rate. For a finite temporal resolution, the negativity is found to be oscillating with respect to both the FSS and the spin-flip rate. This oscillatory behavior disappears for perfect temporal resolution and maximal entanglement is retrieved despite the flip-flop process.