Quantum mechanics has played an increasing role in electrical engineering over the past several decades. While devices like lasers and transistors are based on quantum mechanical principles, they still operate on classical signals and produce classical outputs. More recent devices, on the other hand, have been developed to store and manipulate quantum bits of information and transmit quantum signals. These quantum devices enable many new applications, including quantum computers that can solve certain seemingly intractable computational problems, quantum cryptography systems that allow provably secure communication, and quantum sensors that enable measurement sensitivity beyond what is classically possible. These technologies are pursued both experimentally and theoretically in our department using new semiconductor spin systems, superconducting circuits, and quantum optics.