Building efficient light-matter interfaces for quantum systems

Abstract

Efficient collection of photons from quantum memories, such as quantum dots (QDs) and nitrogen vacancy (NVs) centers in diamond, is essential for various quantum technologies. This thesis describes the design, fabrication, and utilization of novel photonic structures and systems to achieve potentially world-record photon collection from quantum dots. This technique can also be applied to NVs in diamond in the near future. Also, the NV- charged state has second-scale coherence times at room temperature that make it a promising candidate for solid state memories in quantum computers and quantum repeaters. NV- is an individually addressable qubit system that can be optically initialized, manipulated, and measured. On-chip entanglement generation would be the basis of scalability for quantum information processing technologies. These properties have enabled recent demonstrations of heralded quantum entanglement and teleportation between two separated NV centers. To improve the entanglement probability in such schemes, it is imperative to improve the efficiency with which single photons from a NV center can be guided into a low-loss single-mode waveguide. As such, a second component of this thesis focuses on the development of a photonic integrated circuit based on aluminum nitride that would incorporate pre-selected, long-lived NV center quantum memories as well as pre-selected, high-performance superconducting nanowire single-photon detectors (SNSPDs). This hybrid device would have the capability to perform on-chip entanglement of photons from separate quantum memories to build up a quantum repeater necessary for long-distance quantum communication and distributed quantum computing.