Event
Ph.D. Dissertation Defense: Yuxi Jiang
Thursday, August 27, 2026
2:00 p.m.
AVW 2460
Emily Irwin
301 405 0680
eirwin@umd.edu
Announcement: Ph.D. Dissertation Defense
Name: Yuxi Jiang
Committee:
Professor Edo Waks, Chair/Advisor
Professor Saikit Guha
Professor Norbert M. Linke, Dean's Representative
Professor Avik Dutt
Professor You Zhou
Date/time: Thursday, August 27 at 2:00 PM
Location: AVW 2460
Zoom link: https://umd.zoom.us/j/
Title: Optically Active Donor Spin Qubits In ZnSe
Abstract: Donor impurities in direct-band-gap II–VI semiconductors have single-electron spin ground states and can couple to optically bright donor-bound exciton states. These properties make them promising candidates for optically active spin qubits. This thesis aims to establish the optical donor as a promising solid-state platform for quantum computing and quantum networking. It focuses on the development of a coherent quantum-optical system and the experimental techniques needed to control its optical and spin states.
Individual donors are isolated in ZnSe quantum wells, and are integrated into nanophotonic structures. Nanopillars and bullseye optical cavities are developed to improve the collection efficiency of quantum light emitted by single donor-bound excitons. Resonance fluorescence is then measured under resonant excitation of a single bound exciton, demonstrating that the bound exciton can emit phase-coherent quantum light.
The thesis then shows optical control of the electron spin bound to a single donor. Resonant lasers are used to initialize, control, and read out the spin ground state. Coherent population trapping (CPT) measurements are performed using the donor-bound exciton transitions to probe the electron spin ground-state coherence. Additionally, off-resonant ultrafast optical pulses are used to drive coherent Rabi oscillations and generate Ramsey interference of the donor spin. Together, these measurements validate coherent optical control of a single donor electron spin in ZnSe.
The experiments also determine several key properties of the ZnSe donor system, including the bound-exciton optical linewidth, the donor discharge time, and the spin relaxation and dephasing times. Furthermore, hyperfine coupling between the chlorine nucleus and the donor electron spin is observed through power-dependent CPT measurements. These results provide a foundation for controlling the optical, electron-spin, and nuclear-spin degrees of freedom of donors in II–VI semiconductors.
The thesis concludes with an outlook on pathways for improving optical and spin coherence, and integrating donor spins into scalable nanophotonic and electronic architectures. The combination of bright optical transitions, coherent spin control, and a host material with a reduced nuclear-spin environment makes donors in ZnSe a promising platform for spin–photon interfaces and future quantum networking platforms.
