Theme 3 colloquium by Prof. Rudolf Bratschitsch (Univ.Munster, Germany): 'Single-photon emitters in atomically thin materials' (Lecture)

Atomically thin materials serve as a promising new material class for optoelectronics. Monolayer semiconductors such as MoS2 or MoSe2 exhibit prominent photoluminescence. Recently, we have discovered bright and stable single-photon emitters in single layers of WSe2 [1], which renders atomically thin semiconductors also interesting for quantum optics and quantum technologies [2]. In my talk, I will show that these quantum light sources can be controlled by mechanical strain and demonstrate deterministic positioning of the emitters on the nanoscale [3]. Furthermore, I will present single-photon emission from GaSe [4], and demonstrate that the photons can be routed in dielectric waveguides on a photonic chip [5]. Finally, I will discuss the nature and prospects of single-photon emitters in the van der Waals insulator hexagonal boron nitride (hBN). I will focus on how large emitter arrays can be created with commercially available hBN nanocrystals [6], demonstrate ultrafast coherent control of a single hBN emitter [7], and show how the emitted single photons can be efficiently collected in the far field with 3D-printed polymer lenses [8].

References:
         [1]     P. Tonndorf et al., Optica 2, 347 (2015)
         [2]     S. Michaelis de Vasconcellos et al., Phys. Status Solidi B 259, 2100566 (2022)  (review)
         [3]     J. Kern, Advanced Materials 28, 7101 (2016)
         [4]     P. Tonndorf et al., 2D Materials 4, 021010 (2017)
         [5]     P. Tonndorf et al., Nano Letters 17, 5446 (2017)
         [6]     J. A. Preuß et al., 2D Materials 8, 035005 (2021)
         [7]     J. A. Preuß et al., Optica 9, 522 (2022)
         [8]     J. A. Preuß et al., Nano Letters 23, 407 (2023)