Professor Ian Walmsley CBE FRS FCGI

Abstract:

We demonstrate experimentally the realization of heralded pure photons generation in a birefringent optical fiber. © 2008 Optical Society of America.

Abstract:

We experimentally demonstrate a heralded source of high-purity two-photon NOON states derived from heralded single-photon sources. © 2008 Optical Society of America.

Abstract:

Quantum storage of multiple optical modes affords improved performance for quantum repeaters. We present new analytic and numerical results unifying the scaling of the multimode storage capacity for various memory protocols in artificially broadened ensembles. © 2008 Optical Society of America.

Abstract:

In an experiment reported recently (Mosley et al 2008 Phys. Rev. Lett. 100 133601), we demonstrated that, through group velocity matched parametric downconversion, heralded single photons can be generated in pure quantum states without spectral filtering. The technique relies on factorable photon pair production, initially developed theoretically in the strict collinear regime; focusing-required in any experimental implementation-can ruin this factorability. Here, we present the numerical model used to design our single photon sources and minimize spectral correlations in the light of such experimental considerations. Furthermore, we show that the results of our model are in good agreement with measurements made on the photon pairs and give a detailed description of the exact requirements for constructing this type of source. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Abstract:

Light storage in atomic ensembles has been implemented successfully, but the retrieval efficiency can be low. We propose to improve this efficiency with appropriately phase-matched backward propagating retrieval. This method allows for easy spatial filtering of the retrieved light; in addition, multiple optical modes can be stored in the transverse momentum of the ensemble. We model walk-off effects with a full numerical simulation, and confirm the applicability of the scheme. © 2008 The American Physical Society.