Projects per year
Abstract
This thesis explores the theoretical and experimental aspects of cavity optomechanics, with a primary focus on cooling mechanical resonators using a new approach: coherent feedback cooling. Optomechanics, where light interacts with mechanical resonators, has become a vital platform for probing quantum behavior in macroscopic systems and improving precision sensing technologies. A significant challenge in this area is the cooling of mechanical systems to their quantum ground state, which traditionally relies on measurement-based feedback mechanisms.
We developed a theoretical framework that leverages coherent feedback control to cool a mechanical oscillator without direct measurement of the optical field, preserving the system’s quantum coherence. We demonstrated how coherent feedback can effectively reduce thermal motion by successfully cooling a macrospic mechanical resonator to temperatures as low 10.8mK.
While the results were promising, we encountered technical challenges such as thermal noise from mirrors affecting the transduction of frequency fluctuations, limiting coupling efficiency and precision. To address these limitations, we propose several improvements, including the use of phononic-structured cavity mirrors, enhanced stabilization of intensity to reduce radiation pressure noise, and optimizing the feedback mechanism at lower power to prevent the addition of thermal phonons.
This thesis establishes a strong foundation for further advancements in the field of cavity optomechanics. By addressing the outlined challenges, coherent feedback cooling holds great promise for achieving quantum-limited measurements and enhancing the performance of quantum information and sensing technologies.
We developed a theoretical framework that leverages coherent feedback control to cool a mechanical oscillator without direct measurement of the optical field, preserving the system’s quantum coherence. We demonstrated how coherent feedback can effectively reduce thermal motion by successfully cooling a macrospic mechanical resonator to temperatures as low 10.8mK.
While the results were promising, we encountered technical challenges such as thermal noise from mirrors affecting the transduction of frequency fluctuations, limiting coupling efficiency and precision. To address these limitations, we propose several improvements, including the use of phononic-structured cavity mirrors, enhanced stabilization of intensity to reduce radiation pressure noise, and optimizing the feedback mechanism at lower power to prevent the addition of thermal phonons.
This thesis establishes a strong foundation for further advancements in the field of cavity optomechanics. By addressing the outlined challenges, coherent feedback cooling holds great promise for achieving quantum-limited measurements and enhancing the performance of quantum information and sensing technologies.
Original language | English |
---|
Publisher | Department of Physics, Technical University of Denmark |
---|---|
Number of pages | 132 |
Publication status | Published - 2024 |
Fingerprint
Dive into the research topics of 'Room temperature optical cooling of a macroscopic mechanical resonator'. Together they form a unique fingerprint.Projects
- 1 Finished
-
Control of high-quality mechanics with squeezed state of light
Filho, L. C. C. P. (PhD Student), Andersen, U. L. (Main Supervisor), Hoff, U. B. (Supervisor), Neergaard-Nielsen, J. S. (Supervisor), Dantan, A. R. (Examiner) & Wieczorek, W. (Examiner)
01/02/2021 → 14/01/2025
Project: PhD