On the use of photonic spatial degree of freedom as a quantum bit

Abstract

In photonic quantum information processing, the polarization degree of freedom of a photon is the most often used choice of the quantum bit. However, other degrees of freedom of the photon may be used to represent quantum information. One such choice is to use the spatial degree of freedom of a photon as the quantum bit. For a photonic spatial quantum bit, however, performing an arbitrary basis measurement has always been a problem. In this talk, we show how an arbitrary basis measurement for a photonic spatial quantum bit may be performed. It will be shown that a complete parallel between the polarization quantum bit and the! spatial quantum bit (of a photon) can be established.