DFG Research Grant: Three-Dimensional Quantum Photonic Elements Based on Single Emitters in Laserwritten Microstructures for Efficient Non-Classical Light Generation and Ultra-Sensitive Optical Nanomagnetometry

The goal of this project is to demonstrate efficient non-classical light generation and ultrasensitive optical nanomagnetometry as two key functionalities of novel three-dimensional nanophotonic structures realised with a unique and highly versatile technology. The approach is to utilise a color defect center in a nanodiamond as a single stable quantum system together with dielectric and metallic nano-architectures fabricated by on-demand direct laser writing (DLW). The color center is a nitrogen-vacancy (NV) defect which on the one hand is a source of single magnetometer with high-sensitivity and nanometer spatial resolution. Our project introduces for the first time a reliable and cost-efficient assembly method for almost arbitrary quantum photonic elements. The fabrication scheme is easy to implement and requires no elaborate clean-room environment. It overcomes the limit of established approaches based on multi-layers or membranes and introduces true three-dimensional structures operating at the fundamental quantum level with single photons or exploiting single spins. Moreover, we strive to combine multiple functionalities in an integrated platform for the first time. Examples are resonator or plasmon-based enhancement of light collection for improving optical spin read-out or integration of single spin magnetometers in a microfluidic cell. In our project two groups join their complementary expertise which is quantum optical measurements in integrated nanosystems and single photon physics at Humboldt-Universität as well as nanophotonics and direct laser writing technology at the Karlsruhe Institute of Technology (KIT).