Zhu Chenglian, Feld Leon G, Boehme Simon C, Cherniukh Ihor, Bodnarchuk Maryna I, Kovalenko Maksym V, Rainò Gabriele
Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland.
Laboratory for Thin Films and Photovoltaics, Empa - Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland.
Nano Lett. 2025 Sep 10;25(36):13453-13461. doi: 10.1021/acs.nanolett.5c02608. Epub 2025 Sep 1.
Beyond single-photon emission, generating correlated -photon bundles, e.g., a photon pair, is essential for various quantum technologies including quantum teleportation and metrology. A widely explored approach exploits the radiative biexciton cascade in individual (mainly epitaxially grown) quantum dots (QDs). Here, we investigate such a cascade in colloidal CsPbBr QDs, a scalable and solution-processable quantum-light emitter. By matching their size-dependent biexciton binding energies to their size-independent phonon energies, we demonstrate the generation of time-correlated and energy-degenerate photon pairs in large (>15 nm) QDs. Under pulsed excitation at 4 K, we observe pronounced photon bunching, with a g(0) of up to 7 in Hanbury Brown and Twiss measurements. The excitation-density-dependent bunching is quantitatively reproduced by multicolor numerical calculations, suggesting the cascade involving biexciton and phonon-mediated exciton decay as origin of the photon pair. Our findings provide new insights into energy-degenerate photon-pair generation in these highly engineerable quantum-light emitters, marking important steps toward their application in quantum-information technologies.
除了单光子发射外，生成关联光子束，例如光子对，对于包括量子隐形传态和计量学在内的各种量子技术至关重要。一种广泛探索的方法利用了单个（主要是外延生长的）量子点（QD）中的辐射双激子级联。在这里，我们研究了胶体CsPbBr量子点中的这种级联，它是一种可扩展且可溶液处理的量子光发射器。通过将其与尺寸相关的双激子结合能与尺寸无关的声子能量相匹配，我们证明了在大尺寸（>15 nm）量子点中产生时间相关且能量简并的光子对。在4 K的脉冲激发下，我们在汉伯里·布朗和特威斯测量中观察到明显的光子聚束，g(0)高达7。多色数值计算定量地再现了与激发密度相关的聚束，表明双激子和声子介导的激子衰变级联是光子对的起源。我们的发现为这些高度可工程化的量子光发射器中能量简并光子对的产生提供了新的见解，标志着它们在量子信息技术中应用的重要进展。
