Measurement and Control of Micromechanical Oscillators in the Quantum Regime

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School of Science | Doctoral thesis (article-based) | Defence date: 2024-10-04
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Author
Date
2024
Department
Teknillisen fysiikan laitos
Department of Applied Physics
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Mcode
Degree programme
Language
en
Pages
79 + app. 53
Series
Aalto University publication series DOCTORAL THESES, 190/2024
Abstract
Micro- and nanomechanical devices are key components ubiquitous in many real-world applications, and have become indispensable tools for fundamental studies in physics, in particular, macroscopic quantum phenomena of the motion of mechanical objects. However, a significant challenge in exploring the quantum nature of these devices arises from the thermal disturbances of the environment, which induce decoherence and obscure their quantum properties. Advancements in microfabrication, as well as cooling techniques such as direct refrigeration and cooling methods developed based on quantum control protocols, have propelled the study of macroscopic mechanical systems into the quantum regime. The micromechanical devices studied in this thesis are superconducting microwave circuits in which aluminum drumhead mechanical oscillators are strongly coupled to the circuit electromagnetic resonances. This circuit configuration, sometimes termed circuit electromechanics, can be viewed as a circuit realization of cavity optomechanics, which explores the interaction between the micromechancial motion and electromagnetic radiation. Important experimental verifications in eletromechanics have been recently demonstrated, including ground-state cooling, entanglement between two drumhead oscillators, and quantum squeezing of micromechanical motion.  In this thesis, several endeavors aimed at achieving quantum control of micromechanical motion are experimentally investigated for the first time. We first implemented feedback control in circuit electromechanics and achieved feedback cooling of a 8 MHz oscillator near to its motional ground state, limited by added amplifier noise. We also explored the possibility of using feedback to stabilize an otherwise unstable regime in optomechanics. These attempts may establish the possibility of preparing non-classical motional quantum states using feedback. Next, we considered a noise-driven approach in optomechanics, in which we inject strong band-limited electromagnetic noise into the motional sideband of a multi-mode circuit optomechanical device. Ground-state cooling and optomechanical heating phenomena are investigated with different noise driving conditions. Additionally, we found an adiabatically driven regime of mechanical motion via narrowband field driving. The study holds the potential to yield some insights into the behavior of complex systems, when the system is driven close to its instability. Efficient quantum control over these systems and the ability to prepare them into target quantum states may open up the possibility of using these mechanical devices as valuable resources for future quantum applications.
Description
Supervising professor
Sillanpää, Mika, Prof., Aalto University, Department of Applied Physics, Finland
Thesis advisor
Mercier de Lépinay, Laure, Asst. Prof., Aalto University, Department of Applied Physics, Finland
Keywords
quantum optomechanics, electromechanical devices, feedback control, noise-driven
Other note
Parts
  • [Publication 1]: Cheng Wang, Louise Banniard, Laure Mercier de Lépinay, and Mika A. Sillanpää. Fast feedback control of mechanical motion using circuit optomechanics. Physical Review Applied, 19, 054091, May 2023.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202308014503
    DOI: 10.1103/PhysRevApplied.19.054091 View at publisher
  • [Publication 2]: Cheng Wang, Louise Banniard, Kjetil Børkje, Francesco Massel, Laure Mercier de Lépinay, and Mika A. Sillanpää. Ground-state cooling of a mechanical oscillator by a noisy environment. Nature Communication. s, 15, 7395, August 2024.
    Full text in Acris/Aaltodoc: https://urn.fi/URN:NBN:fi:aalto-202409116304
    DOI: 10.1038/s41467-024-51645-7 View at publisher
  • [Publication 3]: Louise Banniard, ChengWang, Davide Stripe, Kjetil Børkje, Francesco Massel, Laure Mercier de Lépinay, and Mika A. Sillanpää. Optomechanics driven by noisy and narrowband fields. Submitted to Journal of Low Temperature Physics, arXiv:2406.00546v1 (2024).
    DOI: 10.48550/arXiv.2406.00546 View at publisher
Citation
Permanent link to this item
https://urn.fi/URN:ISBN:978-952-64-2017-2
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[diss] Perustieteiden korkeakoulu / SCI