Toward Coherent Polaritonic Devices Operating at Room Temperature

Exciton–polariton condensates are a promising platform for analog computation due to their macroscopic coherence and the ability to manipulate and address them optically. Patterned structures supporting these condensates further enable the realization of coherent polaritonic circuits. However, most demonstrations have relied on conventional III–V semiconductor platforms operating at cryogenic temperatures or requiring complex fabrication methods. Here, we realize molecular polariton condensate waveguides and related structures that support coherent condensate propagation at room temperature. The platform is based on a Tamm microcavity incorporating Rhodamine 3B Perchlorate embedded in a small‐molecule ionic isolation lattice (SMILES) complex as the excitonic medium, with photonic structures defined by focused ion beam milling. Spatial and momentum‐resolved photoluminescence measurements reveal room‐temperature propagation of polariton condensates in patterned waveguides. We further investigate the condensate blueshift and finite momentum, demonstrating that the condensate remains strongly confined during propagation. As a proof of concept, we also demonstrate condensation in custom geometries, including ring waveguides, Y‐splitters, and a Mach–Zehnder interferometer. These results establish a versatile platform for the rapid prototyping of polaritonic devices and represent an important step toward complex fully integrated polaritonic circuits operating at room temperature.