By combining single-photon technology with semiconductor electro-optical devices we investigate a scheme for a quantum CNOT gate. Such a gate is a fundamental building block of quantum computers and quantum communication systems. Nanofabrication and material-growth concepts will be implemented to create optical micro cavity structures with embedded artificial atoms in the form of a nanoscale semiconductor structure, called a quantum dots. A quantum dot, if positioned at the center of the cavity and at the cavity resonant frequency, will interact with an incoming photon in such a way that the photon polarization will become entangled with the electronic state of the quantum dot. This interaction establishes the quantum CNOT gate; the quantum state of the photon is changed depending on the quantum state of the electron.
The research topic directly relates to the micro optoelectronics industry as well as to fundamental studies of confined electron properties in semiconductors. Potential applications in classical and quantum information storage and processing are expected to follow from this project. Since the interactions are at the single photon level, the devices will in principle be very energy efficient. It should however be mentioned that this study does require low-temperature operation conditions. Alternative implementations based on different cavity designs and different optical emitters that remain active a room temperature will also be considered.
