New Walther Group Paper on the Cover of the first Optica Quantum Issue


The recent publication "Single-active-element demultiplexed multi-photon source" by the Walther Group made it onto the cover of the first issue of Optica Quantum!


Temporal-to-spatial mode demultiplexing routes non-simultaneous events of the same spatial mode to distinct output trajectories. This technique has now been widely adopted, because it gives access to higher-number multi-photon states when exploiting solid-state quantum emitters. However, implementations so far have required an always-increasing number of active elements and are therefore rapidly facing resource constraints. Here, we propose and demonstrate a demultiplexing approach that uses only a single active element for routing to, in principle, an arbitrary number of outputs. We employ our device in combination with a high-efficiency single-photon source based on a quantum dot, and measure up to eight demultiplexed highly indistinguishable single photons. We discuss the practical limitations of our approach, and describe in which conditions it can be used to demultiplex, e.g., tens of outputs. Our scheme thus provides a path for the preparation of resource-efficient larger-scale multi-photon sources.



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