CAREER: Coupling Spin, Light, and Charge for Quantum Information Processing and Storage in Diamond

University Of Pennsylvania, Philadelphia PA

Investigators

Abstract

Nontechnical description: Atom-scale defects in semiconductors -long the bane of conventional integrated electronic devices - could actually form the basis for new generations of devices that harness quantum mechanical effects to achieve transformational new functionalities. Select types of impurities, known as defect spins, exhibit desirable quantum features in room-temperature devices amenable to integration and miniaturization. These defects respond to electric, magnetic, and optical fields, and they can be embedded in biocompatible nanoparticles to serve as quantum probes with nanometer precision. The purpose of this CAREER project is to explore new ways to control defect spins in diamond, in order to realize practical technologies for quantum information processing and quantum sensing. Specifically, this project aims to (i) demonstrate a new approach to probing diamond spins with light that dramatically boosts their functionality as quantum bits and quantum probes and (ii) isolate and manipulate coupled impurity spins that could serve as quantum memory bits with lifetimes measured in days at room temperature, improving over the state of the art by many orders of magnitude. These elements will form critical components for quantum computers, secure quantum communication links, and other chip-scale quantum technologies. The project further incorporates broad educational goals to promote the emerging domain of quantum engineering, which breaks traditional boundaries between disciplines such as atomic and solid-state physics, electrical engineering, materials science, chemistry, and biology. It will support the construction and deployment of hands-on demonstrations of quantum coherence, in which K-12 students and the general public can actually see quantum physics with their naked eyes in room-temperature devices. Technical description: Defect spins such as the nitrogen-vacancy (NV) in diamond have clear potential as building blocks for future quantum technologies, but several key challenges impede the development of practical devices. Existing approaches to couple diamond NV spins with single photons require liquid helium temperatures (<10 K), and they are so far incompatible with integrated photonics. Furthermore, nanoscale sensing capabilities are limited by the standard optical readout mechanism for NV spins that requires averaging repeated measurements, which is woefully inefficient. This project will address these challenges by leveraging the complex interplay of charge, orbital, optical, and spin dynamics in diamond impurities. A new technique to achieve all-optical, single-shot NV spin readout at room temperature will facilitate applications including quantum-limited sensing of local fields, probing quantum correlations between multiple spins, and sensing stochastic signals (e.g., neuron activity) that cannot be repetitively acquired. In parallel, investigations of spin and charge dynamics in coupled defect-donor spin systems aim to establish an optically-addressable quantum memory with room-temperature coherence times measured in days, which will enable secure communication technologies including quantum money and quantum repeaters.