Electrical Signal Picks Up a Magnet ’ s Heartbeat

A strong interaction between light and a magnet can produce a hybrid system with energy levels distinct from either the light or the magnet on its own. In this “strong coupling” regime, quantum information can be easily transferred from the light to the magnet and vice versa. This feature could be useful in quantum information technologies or as a way to use one component (say, the light) to probe the other. So far, most experiments have explored strong coupling via its effects on the light. CanMing Hu at the University of Manitoba, Canada, and his colleagues instead detect strong coupling directly from a magnet, which in their experiments is embedded in a microwave cavity [1]. The detection occurs via an electrical signal, suggesting their device could lead to new ways of reading out the quantum state of a magnet with compact electronics.