Quantum Dots

Using a variety of nanophotonic semiconductor quantum dot architectures, optical manipulation techniques, and environmental controls, we work on:

• Advanced excitation schemes to enhance the emitted quantum states of light. We aim to develop universal protocols for the on-demand generation of single and multi-photon states with high preparation fidelity, single-photon purity, and indistinguishability. This has many applications, such as multiplexing, demultiplexing, and coherence control in exciton and photonic states.
• Investigating the creation of entangled photon pairs with high fidelity. Using nanowire samples containing multiple quantum dots stacked on top of each other, we can probe the interactions among them and also generate many single photons at a time. Building on this, we study states that lead to multi-photon emission and have potential as sources of multipartite entangled photon states.
• Studying the magnetic manipulation of quantum states using vector magnetic fields in the x- and z-directions. When combined with chirped laser pulses, it becomes possible to coherently access optically forbidden dark exciton states. Due to their longer lifetimes compared to optically allowed exciton states, dark excitons are ideal for deterministic generation of time-bin entangled states.

Our project "Bright Entanglement via Dark States" (BRAIDS) aims at generating single time-bin entangled photon pairs from semiconductor quantum dots utilizing dark exciton states as metastable levels.