Modern 12.5 and 28 gigabit SerDes are around 15 to 20 picojoules per bit when being used for something like PCIe3 over your standard FR4 PCB traces, while longe

Modern 12.5 and 28 gigabit SerDes are around 15 to 20 picojoules per bit when being used for something like PCIe3 over your standard FR4 PCB traces, while longer distance (like the linked work) is in the 30pJ/bit range. 1.3 picojoules/bit is a hug advancement, as the only things that get that low are over very short distances (I am working with a brand new SerDes for multi chip module communication that has an amazing 1pJ/bit, but only up to ~24mm).