We propose a spatially multiplexed single-photon source where the structure of the applied binary-tree multiplexer is optimized systematically during its construction. Along the building procedure of this type of multiplexer, the position of a binary photon router appended to the tree in a step of the expansion is determined by taking into account the current achievable single-photon probability of the source. The method chooses the position where this probability is maximal. We determine the stepwise optimized binary-tree multiplexers for experimentally realizable values of the loss parameters, and for a fixed number of routers. The method is scalable, that is, it is possible to determine the multiplexer with an optimal structure for any number of photon routers. We show that single-photon sources based on stepwise optimized binary-tree multiplexers yield higher single-photon probabilities than single-photon sources based on any spatial multiplexer types discussed in the literature thus far in the considered ranges of the loss parameters.

中文翻译：

---

基于逐步优化二叉树复用器的单光子源

我们提出了一种空间复用的单光子源，其中所应用的二叉树复用器的结构在其构造过程中进行了系统优化。在这种类型的复用器的构建过程中，在扩展步骤中附加到树的二元光子路由器的位置是通过考虑源当前可实现的单光子概率来确定的。该方法选择该概率最大的位置。我们确定了逐步优化的二叉树多路复用器，用于实验上可实现的损耗参数值和固定数量的路由器。该方法是可扩展的，即可以为任意数量的光子路由器确定具有最佳结构的复用器。我们表明，在考虑的损耗参数范围内，基于逐步优化的二叉树多路复用器的单光子源比基于迄今为止文献中讨论的任何空间多路复用器类型的单光子源产生更高的单光子概率。