By performing a full analysis of the projected local density of states (LDOS) in a photonic crystal waveguide, we show that phase plays a crucial role in the symmetry of the light-matter interaction. By considering a quantum dot (QD) spin coupled to a photonic crystal waveguide (PCW) mode, we demonstrate that the light-matter interaction can be asymmetric, leading to unidirectional emission and a deterministic entangled photon source. Further we show that understanding the phase associated with both the LDOS and the QD spin is essential for a range of devices that can be realized with a QD in a PCW. We also show how suppression of quantum interference prevents dipole induced reflection in the waveguide, and highlight a fundamental breakdown of the semiclassical dipole approximation for describing lightmatter interactions in these spin dependent systems.

APS
doi.org/10.1103/PhysRevLett.115.153901
Phys. Rev. Lett.

Young, A. B., Thijssen, A. C. T., Beggs, D. M., Androvitsaneas, P., Kuipers, K., Rarity, J. G., … Oulton, R. (2015). Polarization Engineering in Photonic Crystal Waveguides for Spin-Photon Entanglers. Phys.Rev.Lett., 115(Article number: 153901), 1–5. doi:10.1103/PhysRevLett.115.153901