Deterministic coupling between photonic nodes in a quantum network is an essential step toward implementing various quantum technologies. The omnidirectionality of free-standing emitters, however, makes this coupling highly inefficient, in particular if the distant nodes are coupled via low numerical aperture (NA) channels such as optical fibers. This limitation requires placing quantum emitters in nanoantennas that can direct the photons into the channels with very high efficiency. Moreover, to be able to scale such technologies to a large number of channels, the placing of the emitters should be deterministic. In this work, we present a method for directly locating single free-standing quantum emitters with high spatial accuracy at the center of highly directional bullseye metal–dielectric nanoantennas. We further employ non-blinking, high quantum yield colloidal quantum dots for on-demand single-photon emission that is uncompromised by instabilities or non-radiative exciton recombination processes. Taken together, this approach results in a record-high collection efficiency of 85% of the single photons into a low NA of 0.5, setting the stage for efficient coupling between on-chip, room temperature nanoantenna-emitter devices and a fiber or a remote free-space node without the need for additional optics.

中文翻译：

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通过确定性地将量子点放置在纳米天线中，具有接近统一的收集效率的单光子源

量子网络中光子节点之间的确定性耦合是实现各种量子技术的重要步骤。然而，独立式发射器的全向性使得这种耦合非常低效，特别是如果遥远的节点是通过低数值孔径（NA）通道（例如光纤）耦合的。此限制要求将量子发射器放在纳米天线中，该天线可以将光子高效地引导到通道中。此外，为了能够将此类技术扩展到大量通道，发射器的位置应确定。在这项工作中，我们提出了一种将具有高空间精度的单个独立式量子发射器直接定位在高度定向的靶心金属-电介质纳米天线中心的方法。我们进一步采用不闪烁的方式，用于按需单光子发射的高量子产率胶体量子点，不受不稳定或非辐射激子复合过程的影响。综上所述，此方法可将创纪录的85％的单光子收集效率转换为0.5的低NA，从而为在芯片上，室温下的纳米天线发射器设备与光纤或远程设备之间进行有效耦合奠定了基础。自由空间节点，无需额外的光学器件。