An integrated photonic device in diamond to generate quantum entanglement, a computational resource for quantum information processing

University Of Washington, Seattle WA

Investigators

Abstract

Abstract title: An integrated photonic device in diamond to generate quantum entanglement, a computational resource for quantum information processing Abstract: Nontechnial description: This project seeks to demonstrate a quantum device that is an essential building block in a quantum computing network. The device will generate entanglement, a computational resource, between two electron spins in diamond. The main challenge for generating entanglement between spins is performing the operation quickly compared to the entanglement lifetime. Prior experiments in diamond which utilized free-space optical components realized generation rates in the 10-100 millihertz regime. Here we seek to utilize integrated photonics to realize kilohertz rates. The materials platform contains an optical waveguiding layer built in the semiconductor gallium phosphide. This waveguiding layer connects quantum nodes composed of nitrogen-vacancy centers in diamond. A third detetor layer, made from the superconducting material niobium nitride, is used to detect the photons emitted from the nitrogen-vacancy centers. Kilohertz entanglement rates in a scalable platform will enable the realization of large quantum networks. These networks can be utilized to solve computational problems which cannot be solved on a classical computer. Graduate and undergraduates involved in the research will be trained in the design, fabrication, and testing of cutting edge photonic and quantum device technologies. Additionally, a mobile, hands-on demonstration table, which presents fundamental concepts of materials science through diamond-based activities, will be developed and employed at the University of Washington and Seattle-wide science outreach events. Technical description: Atomic-like solid-state defects are attractive candidates for scalable quantum information processing due to the potential to integrate these defects into devices. However, the challenges associated with tuning the individual quantum properties of these defects, as well as the difficulty in controlling interactions between defects, has thus far prohibited the realization of a scalable defect-based quantum network. This works seeks to demonstrate a quantum device, an on-chip entanglement generation unit, that is expected to serve as an essential building block for such a network. A novel, hybrid photonic structure will be utilized that integrates gallium phosphide as an optical device layer with a diamond substrate which hosts the nitrogen-vacancy quantum information nodes. The device utilizes photon interference to generate entanglement, which requires control of the optical properties of individual nitrogen-vacancy centers. This control is provided by integrated electrodes compatible with the gallium phosphide layer. The gallium phosphide device layer enables efficient collection and routing of nitrogen-vacancy photons to waveguide-integrated superconducting detectors to achieve kilohertz electron entanglement rates.