To build tomorrow’s quantum computers, some researchers are turning to dark excitons, which are bound pairs of an electron and the absence of an electron called a hole. As a promising quantum bit, or qubit, it can store information in its spin state, analogous to how a regular, classical bit stores information in its off or on state. But one problem is that dark excitons do not emit light, making it hard to determine their spins and use them for quantum information processing.