This program explores quantum control at the level of single photon, single electron spin, and single nuclear spin in a unique system that features strong coherent coupling between a photon and an electron spin and between an electron spin and a nearby nuclear spin. The experimental studies will be carried out in a cavity QED system, in which a negatively charged nitrogen vacancy (NV) center in a diamond nanopillar couples strongly to a whispering gallery mode (WGM) in a silica microresonator. Proposed research involves close collaborations between the groups at the University of Oregon and the University of Pittsburg, and builds upon recent advances of these two groups in developing a cavity QED system for NV centers and in realizing quantum control of individual electron and nuclear spins, especially quantum state mapping between an electron spin in a NV center and a proximal carbon-13 nuclear spin in the diamond lattice. The primary technical challenges of the proposed research are anticipated to be the development of a well-controlled strong-coupling cavity QED system, the exquisite control of NV excited-state level structures in a nanopillar for dark-state adiabatic evolution, and the efficient readout of electron and nuclear spins.
Broader Impact: Combining quantum control of individual photons, electron spins, and nuclear spins in a solid-state system develops new technical capabilities, creates new model systems, and opens up new possibilities for the emerging field of quantum information science. A light-matter interface with electron and nuclear spins can enable a robust quantum memory for single photons and can also significantly advance our ability to control the coherent coupling between distant and well-isolated nuclear spins. The entanglement of distant nuclear spins or distant electron-nuclear spin pairs in a solid-state environment provides the scientific community an excellent model system to explore fundamental issues of quantum entanglement and error correction. These issues are central to the field of quantum information as well as to our understanding of the quantum world. With a solid-state light-matter interface and with long-lived quantum memory, it might be possible to explore complex quantum networks that can distribute and transport quantum information between distant quantum nodes. The research program also makes important contributions to education and human resource by providing training for graduate and undergraduate students in areas of both scientific and technological importance. This training will prepare the students for careers in academia, industry, and government.
Control of light and matter interactions at very small length scales are critical to the technologies of the future, such as quantum computing, quantum networking and sustainable energy. This project explored how to control this interaction at the smallest possible level allowed by quantum physics, which is a single photon interacting with a single electron or a nucleus. The primary material which we used for this project is diamond, which has been recognized as a very promising material for such future quantum networks and computing. We succeeded in demonstrating extremely accurate and sensitive measurements of the electron diamond using techniques from quantum computing, as well as quantum interactions with the single photon and nucleus. Our methods could enable new approaches to quantum sensing as well, wherein the electron in diamond is used to detect and control the properties of another atom or molecule, again at the quantum level. We proposed a new method for the interaction between the single electron in diamond and a single vibrational mode (called a phonon) associated with a micron scale graphene bridge. Graphene is recognized as one of the other leading candidates for future electronic and optical technology, and our results serve as a way to connect these two promising material platforms. Our project also resulted in the training of several graduate students and undergraduate students in advanced experimental techniques of quantum physics and nanoscience and engineering.
