An experimental demonstration of quantum not gate: Transition from classical to quantum regime

Path of a photon was considered to be used as qubit for implementing quantum NOT gate. An experimental setup was designed using a Mach-Zehnder interferometer constructed from simple optical devices such as He-Ne lasers, beam splitters, mirrors, attenuators etc. and quantum interference was utilized for multi photon case. A number of experiments were performed and the outcome of the experiment was observed by taking a number of photographs of the output beam for a number of input intensities. The observations proved that the setup indeed performed the required NOT transformation with good reliability at multi photon case and thus can be usefully used as a quantum not gate.