Manojkumar V, Varier Geetha K, Vathsan Radhika, Nandakumar P
Department of Physics, Birla Institute of Technology and Science, Pilani, K K Birla Goa Campus, Zuarinagar, Sancoale, Goa, 403726, India.
Sci Rep. 2025 Apr 26;15(1):14639. doi: 10.1038/s41598-025-99148-9.
High repetition rate single-photon emitters are essential for all-optical quantum information processing, communications and metrology. The spontaneous emission lifetimes of colloidal cadmium selenide quantum dots are typically of the order of 10 ns, severely limiting their brightness and therefore their potential applications in quantum devices. Here we report on single-photon emission at room temperature with nanosecond lifetime from cadmium selenide quantum dots embedded in a polymer matrix. The study shows that the emission lifetime can be tuned by appropriately choosing the particle size and the dielectric constant of the surrounding medium. The quantum dots are synthesized using a green synthesis protocol and surface passivated using oleic acid. A Hanbury Brown and Twiss setup attached to an in-house constructed confocal microscope is used to efficiently couple and characterize the single-photon emission from an array of quantum dots. Detailed analysis of the second-order correlation function ([Formula: see text]) of single-photon emission from cadmium selenide quantum dots reveals the particle-size dependence of emission lifetimes. The study also shows that the quality of single-photon emission, as revealed by [Formula: see text], reduces with increasing particle-size in the strongly confined regime.
高重复率单光子发射器对于全光量子信息处理、通信和计量至关重要。胶体硒化镉量子点的自发发射寿命通常在10纳秒左右，这严重限制了它们的亮度，进而限制了它们在量子器件中的潜在应用。在此，我们报道了嵌入聚合物基质中的硒化镉量子点在室温下具有纳秒级寿命的单光子发射。研究表明，通过适当选择粒径和周围介质的介电常数，可以调节发射寿命。量子点采用绿色合成方案合成，并用油酸进行表面钝化。将一个Hanbury Brown和Twiss装置连接到自制的共聚焦显微镜上，用于有效地耦合和表征量子点阵列的单光子发射。对硒化镉量子点单光子发射的二阶关联函数（[公式：见原文]）的详细分析揭示了发射寿命对粒径的依赖性。研究还表明，在强受限区域，如[公式：见原文]所示，单光子发射的质量随着粒径的增加而降低。
