The Joint Quantum Institute and the University of Maryland have created a transistor that is activated by photon interactions. Enabled by a semiconductor chip, the device is the first single-photon transistor. Astonishingly small, it is quite capable. Millions of these transistors could reside within the space of a grain of salt. Yet, the device is able to process nearly 10 billion qubits per second. The device shows promise in advancing quantum computers.