Engineering spin coherence in core-shell diamond nanocrystals

• 成果类型: Article
• 署名作者: Zvi, Uri; Candido, Denis R.; Weiss, Adam M.; Jones, Aidan R.; Chen, Lingjie; Golovina, Iryna; Yu, Xiaofei; Wang, Stella; Talapin, Dmitri V.; Flatte, Michael E.; Esser, Aaron P.; Maurer, Peter C.
• 署名单位: University of Chicago; University of Iowa; University of Chicago; University of Chicago; University of Pennsylvania; United States Department of Energy (DOE); Argonne National Laboratory; United States Department of Energy (DOE); Argonne National Laboratory; Eindhoven University of Technology
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-11474
• DOI: 10.1073/pnas.2422542122
• 发表日期: 2025-05-21
• 关键词: fluorescent nanodiamonds; size distribution; silica; functionalization; luminescence; thermometry; defects; centers; bright; image

摘要

Fluorescent diamond nanocrystals can host spin qubit sensors capable of probing the physical properties of biological systems with nanoscale spatial resolution. Sub-100 nm diamond nanosensors can readily be delivered into intact cells and even living organisms. However, applications beyond current proof-of-principle experiments require a substantial increase in sensitivity, which is limited by surface induced charge instability and electron-spin dephasing. In this work, we utilize engineered core-shell structures to achieve a drastic increase in qubit coherence times (T2) from 1.1 to 35 mu s in bare nanodiamonds to upward of 52 to 87 mu s. We use electron-paramagnetic-resonance results to present a band bending model and connect silica encapsulation to the removal of deleterious mid-gap surface states that are negatively affecting the qubit's spin properties. Combined with a 1.9-fold increase in particle luminescence these advances correspond to up to two-order-of-magnitude reduction in integration time. Probing qubit dynamics at a single particle level further reveals that the noise characteristics fundamentally change from a bath with spins that rearrange their spatial configuration during the course of an experiment to a more dilute static bath. The observed results shed light on the underlying mechanisms governing fluorescence and spin properties in diamond nanocrystals and offer an effective noise mitigation strategy based on engineered core-shell structures.