Integrated photonics promises solutions to questions of stability, complexity, and size in quantum optics. Advances in tunable and non-planar integrated platforms, such laser-inscribed photonics, continue to bring the realisation of quantum advantages in computation and metrology ever closer, perhaps most easily seen in multi-path interferometry. Here we demonstrate control of two-photon interference in a chip-scale 3D multi-path interferometer, showing a reduced periodicity and enhanced visibility compared to single photon measurements. Observed non-classical visibilities are widely tunable, and explained well by theoretical predictions based on classical measurements. With these predictions we extract a Fisher information approaching a theoretical maximum, demonstrating the capability of the device for quantum enhanced phase measurements.
@article{arxiv.1409.4908,
title = {Tuneable quantum interference in a 3D integrated circuit},
author = {Zachary Chaboyer and Thomas Meany and L. G. Helt and Michael J. Withford and M. J. Steel},
journal= {arXiv preprint arXiv:1409.4908},
year = {2015}
}