In quantum optics, photons (particles of light) are used to carry quantum information. Each photon has a polarization — for instance, vertical or horizontal, which can be ascribed with the classic bit states of zero and one, respectively. But polarization can also be in a quantum superposition of these states — essentially zero and one at the same time. Since the means of manipulating the polarization of photons are well understood and easily achievable, optics makes an ideal test-bed for investigating quantum information processing. Some of the first realizations of novel quantum effects, such as teleportation and quantum key distribution, were achieved through optics research.
The seminal proposal by Emanuel Knill, Raymond Laflamme and Gerard Milburn (the Krill, Laflamme, Milburn (KLM) proposal) allows universal and scalable optical quantum computing using only single photons, linear optics and measurement. Institute for Quantum Computing (IQC) faculty member Norbert Lütkenhaus has conducted leading research into such areas as entanglement verification and quantum logic operation. The team led by Kevin Resch focuses on the generation and applications of quantum entanglement, fundamental tests of quantum mechanics and novel approaches to optical imaging. Thomas Jennewein’s optical research team investigates quantum communication through free space via satellite.