Single-photon position to time multiplexing using a fiber array.

A 1 x 8 fiber array is used as the front-end of a receiver system. Each channel has a different length of fiber, resulting in each channel signal arriving at the detector at a pre-determined interval relative to a constant repetitive frequency signal. We demonstrate that these eight channels can be efficiently coupled to an individual single-photon detector such that the arrival-time of a photon in each is distinguishable from the next. Thus, we demonstrate spatial position to time information exchange, resulting in a photon-counting array using a single detector. The receiver system could be implemented in numerous applications, including time-resolved photoluminescence, low-light level spectroscopy and quantum information processing.

Quantum correlations in optical angle-orbital angular momentum variables.

Entanglement of the properties of two separated particles constitutes a fundamental signature of quantum mechanics and is a key resource for quantum information science. We demonstrate strong Einstein, Podolsky, and Rosen correlations between the angular position and orbital angular momentum of two photons created by the nonlinear optical process of spontaneous parametric down-conversion. The discrete nature of orbital angular momentum and the continuous but periodic nature of angular position give rise to a special sort of entanglement between these two variables. The resulting correlations are found to be an order of magnitude stronger than those allowed by the uncertainty principle for independent (nonentangled) particles. Our results suggest that angular position and orbital angular momentum may find important applications in quantum information science.