CAREER: Quantum Light-Matter Interfaces Based on Rare-Earth Ions and Nanophotonics

California Institute Of Technology, Pasadena CA

Investigators

Abstract

Title: Quantum Light-Matter Interfaces Based on Rare-earth-doped Crystals and Nanophotonics for On-chip Storage and Retrieval of Photonic Quantum States Non-Technical Description: Information utilized by our society is processed using electrical signals in computer microprocessors, and transmitted long distances using optical signals travelling in fiber networks that form the backbone of the Internet. The performance of these technologies is reaching fundamental limits, so quantum machines are expected to drive the next technological revolution. These machines process information by manipulating the most fundamental properties of atoms and photons, their quantum states. Applications include absolutely secure communications over the Internet, the capability to quickly solve problems like protein folding for drug discovery, and quantum simulation of new materials with extreme properties. Analogous to the current Internet, optical quantum networks will be used to interconnect quantum machines. Quantum networks consist of optical channels where photons travel and nodes where photons are generated, stored and processed using quantum light-matter interfaces. The goal of this research is to develop on-chip light-matter interfaces for storing photons and their quantum states. Depending on the application, the interface could act as a memory where the quantum state is retrieved back into a photon, or the state could be transferred to another quantum device. The interfaces will be implemented using solid-state crystals doped with rare-earth atoms, materials known for their excellent photon storage capability. Established processing techniques from the semiconductor industry will be used to fabricate the light-matter interfaces directly in crystalline chips, thus leading to a scalable platform. The proposed research is situated at the transition between quantum science and quantum engineering. Thus, this project provides an ideal opportunity to educate the general public about this transition, which is happening now, where multiple technologies developed for fundamental quantum science are finding applications in quantum computing, communications and sensing. To reach a broad audience, the principal investigator and members of his group will write articles and develop educational videos that will be posted on scientific blogs. To increase diversity in science and engineering, the research group will be involved in an outreach program with a high school on the Navajo Nation US Indian reservation. Technical description: Quantum light-matter interfaces that reversibly map the quantum state of photons onto the quantum states of atoms, are essential components in the quantum engineering toolbox with applications in quantum communication, computing, and quantum-enabled sensing. The goal of this research is to develop on-chip quantum light-matter interfaces based on nanophotonic resonators fabricated in rare-earth-doped crystals known to exhibit some of the longest optical and spin coherence times in the solid state. The role of nano-scale optical resonators with high quality factors is to enhance the interaction of single photons with small ensembles of rare-earth ions thus enabling compact devices suitable for large-scale integration. The experimental approach merges new nano-fabrication techniques for rare-earth-doped crystals (neodymium doped yttrium orthosilicate), high-resolution laser spectroscopy, and coherent control of atomic quantum states. As a result of this research, the feasibility of developing integrated nanophotonic quantum devices based on rare-earth-doped crystals will be assessed. The optical coherence, the spectral stability and the spin coherence of rare-earth ions embedded in a nano-scale environment will be studied, and techniques for coherent control of their quantum states in on-chip photonic networks will be developed. Optical quantum memories with the smallest footprint to date and their on-chip integration will be demonstrated. This CAREER award is jointly funded by the Electronics, Photonics, and Magnetic Devices (EPMD) Program in the Division of Electrical, Communications and Cyber Systems (ECCS), the Electronic and Photonic Materials (EPM) Program in the Division of Materials Research (DMR), and the Quantum Information Science (QIS) Program in the Division of Physics (PHY).