Quantum information is a rapidly advancing area of interdisciplinary research. It may lead to real-world applications for communication and computation unavailable without the exploitation of quantum properties such as nonorthogonality or entanglement. The field of quantum information has typically concerned itself with the manipulation of discrete systems such as quantum bits, or qubits. However, many quantum variables, such as position, momentum, or the quadrature amplitudes of electromagnetic fields, are continuous, leading to the concept of continuous quantum information.