Friday, May 29, 2009

Efficient all-optical switching using slow light within a hollow-core fiber

By M. Bajcsy, ... , V. Vuletic & M. Lukin

We demonstrate a fiber-optical switch that is activated at tiny energies corresponding to a few hundred optical photons per pulse. This is achieved by simultaneously confining both photons and a small laser-cooled ensemble of atoms inside the microscopic hollow core of a single-mode photonic-crystal fiber and using quantum optical techniques for generating slow light propagation and large nonlinear interaction between light beams.

Thursday, May 14, 2009

Complete path entanglement of two photons

By A. Rossi, ... , F. De Martini & P Mattaloni

We present a novel optical device based on an integrated system of microlenses and single mode optical fibers. It allows to send in many directions two photons generated by spontaneous parametric down conversion. By this device multiqubit entangled states and/or multilevel qu-dit states of two photons, encoded in the longitudinal momentum degree of freedom, are created. The
multipath photon entanglement realized by this device is expected to find important applications in modern quantum information technology.

**Groupmeeting by Yasaman Soudagar**

Monday, May 11, 2009

Experimental Quantum Process Discrimination

By A. Laing, T. Rudolph & J. O'Brien

Discrimination between unknown processes chosen from a finite set is experimentally shown to be possible even in the case of nonorthogonal processes. We demonstrate unambiguous deterministic quantum process discrimination of nonorthogonal processes using properties of entanglement, additional known unitaries, or classical communication. Single qubit measurement and unitary processes and multipartite unitaries (where the unitary acts nonseparably across two distant locations) acting on photons are discriminated with a confidence of >97% in all cases.