Terahertz waves are hard to tame. Ranging between microwaves and infrared light, these electromagnetic frequencies promise ultrafast wireless links but are very difficult to create and manipulate efficiently. Now, new research sheds light on a promising candidate to harness these waves: mercury telluride (HgTe), a material that converts two incoming frequencies into terahertz outputs with record room-temperature efficiency.Tatiana Uaman Svetikova, a Ph.D. candidate at the quantum technologies de...