Devices, systems, methods, computer-implemented methods, apparatus, and/or computer program products that can facilitate an epitaxial Josephson junction transmon device are provided. According to an embodiment, a device can comprise a substrate. The device can further comprise an epitaxial Josephson junction transmon device coupled to the substrate. According to an embodiment, a device can comprise an epitaxial Josephson junction transmon device coupled to a substrate. The device can further comprise a tuning gate coupled to the substrate and formed across the epitaxial Josephson junction transmon device. According to an embodiment, a device can comprise a first superconducting region and a second superconducting region formed on a substrate. The device can further comprise an epitaxial Josephson junction tunneling channel coupled to the first superconducting region and the second superconducting region.