Master Thesis Defense: Thomas Wilkens Sandø-Pedersen

Emission Dynamics of Two Coupled Quantum Dots

The generation of single photons is highly important in quantum photonic technologies like the photonic quantum computer and quantum cryptography. Extending the use of independent single photon emitters to larger states of collective emitters proves a challenge, since the emitters traditionally need to be spatially very close to couple via the electromagnetic force. Using on-chip semiconductor quantum emitters allows the creation of photonic structures around the quantum emitters. In this thesis photonic crystal waveguides are used to direct the photons mediating the electromagnetic interaction between two quantum dots. This way we are able to extend the electro-magnetic dipole-dipole interaction between the dots, and generate coupled emitter states over distances of several wavelengths.

We employ independent tuning of our two quantum dots’ energy levels using local electrical fields, to bring them into resonance. Through measurements of the lifetime of our quantum dots’ excited state and second order correlation function g(2), we are able to detect and explain their collective decay dynamics. We observe signs of both dissipative and dispersive coupling between the quantum dots, as evidenced by directional emission and modified decay rates. Finally some additional noise analysis of the quantum dots is included, as well as some statistical analysis of the feasibility of extending the couple emitter state to several emitters