Preparation and tomographic reconstruction of an arbitrary single-photon path qubit

We report methods for preparation and tomographic reconstruction of an arbitrary single-photon path qubit. The arbitrary single-photon path qubit is prepared losslessly by passing the heralded single-photon state from spontaneous parametric down-conversion through variable beam splitter. Quantum state tomography of the single-photon path qubit is implemented by introducing path-projection measurements based on the first-order single-photon quantum interference. Using the state preparation and path-projection measurements methods for the single-photon path qubit, we demonstrate preparation and complete tomographic reconstruction of the single-photon path qubit with arbitrary purity.

► We report methods for preparation and tomographic reconstruction of an arbitrary single-photon path qubit.
► We implement path-projection measurements based on the first-order single-photon quantum interference.
► We demonstrate preparation and complete tomographic reconstruction of the single-photon path qubit with arbitrary purity.