Mid Term Review
On-chip generation and characterization of entangled photons
Integrated quantum photonic circuits provide a potential platform for scalable quantum technologies with important applications to quantum information processing, communication and imaging. We develop novel integrated photonic structures for the generation entangled photons and the characterization of their quantum state. We present a method for the generation of entangled photon-pairs with all-optical reconfigurability of pair’s wavefunction. This is based on spontaneous parametric down-conversion in coupled waveguide arrays with special domain poling patterns in each waveguide. We also show how this system can allow the production of highly entangled cluster states for measurement based quantum computation. Finally we present a simple ‘one-shot’ method for characterising the density matrix of a quantum state. Typically quantum state tomography requires a large number of different transformations to be applied to a state, and statistics are accumulated after every unitary. Our method requires just a single static unitary transformation followed by correlation measurements.