Heinze Dirk, Breddermann Dominik, Zrenner Artur, Schumacher Stefan
Department of Physics, Center for Optoelectronics and Photonics Paderborn (CeOPP), Universität Paderborn, Warburger Strasse 100, 33098 Paderborn, Germany.
College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA.
Nat Commun. 2015 Oct 5;6:8473. doi: 10.1038/ncomms9473.
Sources of single photons are key elements for applications in quantum information science. Among the different sources available, semiconductor quantum dots excel with their integrability in semiconductor on-chip solutions and the potential that photon emission can be triggered on demand. Usually, the photon is emitted from a single-exciton ground state. Polarization of the photon and time of emission are either probabilistic or pre-determined by electronic properties of the system. Here, we study the direct two-photon emission from the biexciton. The two-photon emission is enabled by a laser pulse driving the system into a virtual state inside the band gap. From this intermediate state, the single photon of interest is then spontaneously emitted. We show that emission through this higher-order transition provides a versatile approach to generate a single photon. Through the driving laser pulse, polarization state, frequency and emission time of the photon can be controlled on-the-fly.
单光子源是量子信息科学应用的关键要素。在现有的不同单光子源中，半导体量子点因其可集成于半导体片上解决方案以及能够按需触发光子发射的潜力而表现出色。通常，光子从单激子基态发射。光子的偏振和发射时间要么是概率性的，要么由系统的电子特性预先确定。在此，我们研究双激子的直接双光子发射。通过激光脉冲将系统驱动到带隙内的虚态来实现双光子发射。然后，从这个中间态自发发射出感兴趣的单光子。我们表明，通过这种高阶跃迁的发射提供了一种生成单光子的通用方法。通过驱动激光脉冲，可以即时控制光子的偏振态、频率和发射时间。
