title: Synthesis and analysis of entangled photonic qubits in spatial-parity space.
abstract: We present the novel embodiment of a photonic qubit that makes use of one continuous spatial degree of freedom of a single photon and relies on the parity of the photon's transverse spatial distribution. Using optical spontaneous parametric down-conversion to produce photon pairs, we demonstrate the controlled generation of entangled-photon states in this new space. Specifically, two Bell states, and a continuum of their superpositions, are generated by simple manipulation of a classical parameter, the optical-pump spatial parity, and not by manipulation of the entangled photons themselves. An interferometric device, isomorphic in action to a polarizing beam splitter, projects the spatial-parity states onto an even-odd basis. This new physical realization of photonic qubits could be used as a foundation for future experiments in quantum information processing.
authors.affiliation: Quantum Imaging Laboratory, Departments of Electrical & Computer Engineering and Physics, Boston University, Boston, Massachusetts 02215-2421, USA.
authors.forename: Timothy
authors.initials: T
authors.lastname: Yarnall
authors.forename: Ayman F
authors.initials: AF
authors.lastname: Abouraddy
authors.forename: Bahaa E A
authors.initials: BE
authors.lastname: Saleh
authors.forename: Malvin C
authors.initials: MC
authors.lastname: Teich