Scalable photonic quantum technologies are based on multiple nested interferometers. To realize this architecture, integrated optical structures are needed to ensure stable, controllable, and repeatable operation. Here we show a key proof-of-principle demonstration of an externally-controlled photonic quantum circuit based upon UV-written waveguide technology. In particular, we present non-classical interference of photon pairs in a Mach-Zehnder interferometer constructed with X couplers in an integrated optical circuit with a thermo-optic phase shifter in one of the interferometer arms.
@article{arxiv.0905.2933,
title = {Phase-controlled integrated photonic quantum circuits},
author = {Brian J. Smith and Dmytro Kundys and Nicholas Thomas-Peter and P. G. R. Smith and I. A. Walmsley},
journal= {arXiv preprint arXiv:0905.2933},
year = {2011}
}