QUANTUM PANCAKES FOR QUANTUM ENTANGLEMENT

9988865量子纠缠对于任何量子信息处理提案所需的量子中继器来说都是必不可少的。这个项目的目标是获得一种足以实现量子纠缠的量子煎饼。“好”指的是具有大的偶极矩和辐射支配的寿命和退相干时间的粒子。大的偶极矩允许人们用真空场或施加的光脉冲比非辐射消相干时间更快地光学控制煎饼。基于窄线宽InGaAs/GaAs量子阱的生长和辐射宽度和偶极矩的提取，该方案将进行下一步：通过横向限制这种量子阱直径为100-200 nm的部分来制作量子煎饼。一个好的煎饼可以用在一个小的3D微腔中，实现煎饼的跃迁和光学模式之间的量子纠缠。该方法将从使用传统光学系统寻找空间分辨率为0.8微米的单个量子阱的最佳部分，或使用固体浸没透镜寻找分辨率为0.25微米的单个量子井的最佳部分开始。不同的横向限制技术将被考虑，例如，来自生长在量子井上方的自组织点层的应力，或者通过使用紧密聚焦的激光束的局部加热而相互扩散。候选煎饼将通过多种光学光谱技术进行评估。不同的反射率或吸收将决定积分吸收和偶极矩。将使用MHz分辨率的连续波非线性光谱和皮秒抽运-探测测量来找出单光子吸收的影响。最后，扫描相机对皮秒共振激发后的前向或后向发射的检测将显示偏振衰减在多大程度上是纯辐射的。

9988865KhitrovaQuantum entanglement is essential for quantum repeaters needed for any of the proposals for quantum information processing to have a chance. The goal of this project is to obtain a quantum pancake that is good enough to achieve quantum entanglement. "Good" means one with a large dipole moment and radiatively dominated lifetime and decoherence time. A large dipole moment allows one to optically control the pancake with the vacuum field or an applied optical pulse faster than nonradiative decoherence times. Based on the growth of narrow-linewidth InGaAs/GaAs quantum wells and extraction of the radiative width and dipole moment, this proposal would take the next step: make a quantum pancake by laterally confining a 100- to 200-nm diameter portion of such a quantum well. A good pancake could be used in a small 3D microcavity to achieve quantum entanglement between a transition of the pancake and the optical mode.The approach will begin with a search for the best portions of a single quantum well with 0.8-micron spatial resolution using conventional optics or 0.25-micron resolution with a solid immersion lens. Various techniques for lateral confinement will be considered, for example, stress from a layer of self-organized dots grown above the quantum well or interdiffusion by local heating using a tightly focused laser beam. Candidate pancakes will be evaluated by a multitude of optical spectroscopic techniques. Differential reflectivity or absorption will determine the integrated absorption and dipole moment. MHz-resolution cw nonlinear spectroscopy and picosecond pump-probe measurements will be used to find out the effect of absorption of a single photon. Finally, streak-camera detection of the forward or backward emission following picosecond resonant excitation will show to what extent the polarization decay is purely radiative.