Institute of Semiconductor and Solid State Physics, Johannes Kepler University, Linz4040, Austria.
Secure and Correct Systems Lab, Linz Institute of Technology, 4040Linz, Austria.
Nano Lett. 2023 Feb 22;23(4):1409-1415. doi: 10.1021/acs.nanolett.2c04734. Epub 2023 Feb 6.
Entangled photon pairs are essential for a multitude of quantum photonic applications. To date, the best performing solid-state quantum emitters of entangled photons are semiconductor quantum dots operated around liquid-helium temperatures. To favor the widespread deployment of these sources, it is important to explore and understand their behavior at temperatures accessible with compact Stirling coolers. Here we study the polarization entanglement among photon pairs from the biexciton-exciton cascade in GaAs quantum dots at temperatures up to ∼65 K. We observe entanglement degradation accompanied by changes in decay dynamics, which we ascribe to thermal population and depopulation of hot and dark states in addition to the four levels relevant for photon pair generation. Detailed calculations considering the presence and characteristics of the additional states and phonon-assisted transitions support the interpretation. We expect these results to guide the optimization of quantum dots as sources of highly entangled photons at elevated temperatures.
纠缠光子对对于许多量子光子应用至关重要。迄今为止，性能最好的纠缠光子固态量子发射器是在液氦温度下工作的半导体量子点。为了促进这些光源的广泛应用，探索和了解它们在使用紧凑型斯特林冷却器可达到的温度下的行为非常重要。在这里，我们研究了 GaAs 量子点中双激子-激子级联产生的光子对在高达约 65 K 的温度下的偏振纠缠。我们观察到纠缠退化伴随着衰减动力学的变化，我们将其归因于热态和暗态的热布居和去布居，以及与光子对产生相关的四个能级。考虑到附加态的存在和特性以及声子辅助跃迁的详细计算支持了这一解释。我们预计这些结果将指导优化量子点作为高温下高纠缠光子源。
