Scalable and Spectrally Uniform Single Photon Sources in Spatially Regular Large Arrays*

Towards realizing on-chip quantum optical circuits, a long-standing obstacle has been the lack of spectrally uniform on-demand single photon sources (SPSs) in designed position, and having optical characteristics satisfying all functional requirements.

We present results on realizing large area spectrally uniform and spatially regular epitaxial quantum dot, mesa top single quantum dots (MTSQDs), that have already been demonstrated to be on-demand SPSs with its characteristics meeting all requirements for photonic quantum information processing [1-4]. Previous results are limited to 5x8 array of MTSQDs, but minimum hundreds to thousands of SPSs are needed for real applications. Thus we report on arrays scaled up to 100x100.. A special wavelength resolved PL imaging technique with 1.6nm resolution was implemented to study the large area MTSQD array spectral characteristics. The results show MTSQDs in large arrays have high spectral uniformity σ<!--[if gte msEquation 12]> style='mso-bookmark:_Hlk148383750'> style='font-size:11.0pt;font-family:"Cambria Math",serif'>σ~3.5nm. Scanning transmission electron microscopy (STEM) result shows high accuracy of MTSQD position control to within ~5nm. With a standard wavelength tuning range of ~2nm, 43% of MTSQD can be tuned into resonance to allow controlled interference between different MTSQDs. Our results suggest that MTSQDs are a highly promising platform towards realizing scalable on-chip quantum optical circuits.