Event
Ph.D. Research Proposal Exam: Xiechen Zheng
Monday, May 13, 2024
12:45 p.m.
AVW 2460
Maria Hoo
301 405 3681
mch@umd.edu
ANNOUNCEMENT: Ph.D. Research Proposal Exam
Name: Xiechen Zheng
Committee:
Professor Ronald Walsworth (Chair)
Professor Yanne Chembo
Professor Cheng Gong
Date/time: Monday, May 13, 2024 at 12:45 pm
Location: AVW 2460
Title: All-optical, Microwave-free Quantum Diamond Magnetometer
Abstract:
Nitrogen-vacancy (NV) centers in diamonds are a leading quantum sensor modality with good magnetic sensitivity and outstanding spatial resolution, down to the nanoscale under ambient conditions. Traditional NV magnetometry protocols rely on GHz-range microwave sources to selectively manipulate the NV sensor’s electronic spin states for optimal sensitivity. However, these microwave signals may introduce perturbations to the sample of interest or prove incompatible with specific operational conditions. This research aims to explore an alternative all-optical, microwave-free NV magnetometry protocol. The findings of the research could pave the way for a more compact and energy-efficient quantum sensor, enabling a broader range of applications, such as diagnosis within nuclear fusion reactors, where the presence of strong magnetic and radiation fields may adversely affect conventional electronic devices.
In this proposal, we initiate our study by investigating the NV photoluminescence (PL) quenching effect under a strong off-axis magnetic field. We explore the reduction in PL intensity due to spin mixing and calibrate the all-optical sensitivity at magnetic fields ∼ 300 mT. By incorporating a multimode optical fiber into the design, we achieve a smaller sensor size while maintaining efficient optical collection.
Additionally, we study the all-optical PL dynamics near zero magnetic field. We characterize rich PL features by varying magnetic fields (< 0.2 mT); and find reasonable agreement between these observations and a model accounting for cross-relaxation effects between different NV centers, as well as hyperfine coupling between NV electronic spins and nuclear spins in the diamond lattice. We propose utilizing the Lorentzian lineshapes of these all-optical features for sensitive, microwave-free magnetometry under weak magnetic fields.
