Room-temperature quantum devices: innovations in active pre-cooling protocol, spin-phonon coupling devices, and stable molecular spins
File(s)
Author(s)
Chen, Kuan-Cheng
Type
Thesis or dissertation
Abstract
The feasibility of active pre-cooling (APC) by temporarily over-coupling microwave cavity modes to a low-noise amplifier acting as an active cold load was demonstrated, offering an effective method to reduce thermal photon occupancy without cryogenic cooling. The potential of the organic radical BDPA as a tunable qubit medium with remarkably long spin-lattice and spin coherence relaxation times was assessed, comparing favorably with state-of-the-art molecular qubit media. A high-quality surface acoustic wave device integrated with pentacene-deposited molecular thin films was developed to achieve heterogeneous optically-detected spin acoustic resonance (HODSAR), enabling efficient zero-field spin control at room temperature via spin-phonon coupling. Through the construction of specialized experimental setups, the effectiveness of these techniques was demonstrated, facilitating pre-cooling of cavity modes, enhancing coherence times in qubit media, and achieving precise spin manipulation. While APC offers advantages over methods like masers and anti-masers, challenges such as the need for fast, low-loss microwave switches remain. The BDPA radicals showed significant promise for spin ensemble, and the SAW-based HODSAR device provides a scalable platform for spin manipulation in quantum technologies.
Version
Open Access
Date Issued
2024-11-04
Date Awarded
2025-02-01
Copyright Statement
Attribution-NonCommercial 4.0 International Licence (CC BY-NC)
License URL
Advisor
Oxborrow, Mark
Heutz, Sandrine
Sponsor
Ministry of Education Republic of China (Taiwan)
Publisher Department
Department of Materials
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)