Cavity optomechanics with nm-thick membranes
<p>This thesis focuses on fast and sensitive readout of mechanical motion to answer questions in the foundations of physics. By coupling a silicon nitride membrane to different readout cavities I have explored the thermodynamic costs of time keeping and carried out a bench-top experiment to pu...
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| Format: | Thesis |
| Language: | English |
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2020
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| _version_ | 1826306132973453312 |
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| author | Pearson, AN |
| author2 | Briggs, GAD |
| author_facet | Briggs, GAD Pearson, AN |
| author_sort | Pearson, AN |
| collection | OXFORD |
| description | <p>This thesis focuses on fast and sensitive readout of mechanical motion to answer questions in the foundations of physics. By coupling a silicon nitride membrane to different readout cavities I have explored the thermodynamic costs of time keeping and carried out a bench-top experiment to put bounds on the theory of classical channel gravity. In order to reach these aims, I have developed real time displacement measurements of the motion of a nm-thick silicon nitride membrane. For this, a lumped element LC circuit is capacitively coupled to the metallized silicon nitride membrane. This approach allows for the estimation of key parameters without the need for frequency matching or cryogenic cooling. I demonstrate electromechanical characterization of several mechanical modes of the silicon nitride membrane. In addition, I show optomechanically induced transparency on chip in this high loss cavity.</p>
<p>The real time displacement measurements of the membrane’s motion allow the device to be operated as a thermomechanical clock and to be used to investigate a thermodynamic trade-off in a nanoscale clock. The system follows a trade-off derived for the idealised quantum setting, indicating a fundamental universality of a relation previously predicted to hold in the quantum regime.</p>
<p>This system is compatible with cryogenic temperatures, allowing me to actuate and detect the resonance frequency of a membrane at low temperatures. At these temperatures, one can perform tests of the theory of classical channel gravity which models the gravitational interaction as a classical measurement channel. The theory predicts a density dependent heating effect due to the gravitational interactions within the membrane itself. Bounds could be put on this theory using a membrane capacitively coupled to a 3D superconducting microwave cavity which has a much higher Q factor than the LC circuit. With this cavity, I achieved 10 mHz resolution of the mechanical signal, which is required for an accurate estimation of the mode temperature and thus to put bounds on the theory.</p> |
| first_indexed | 2024-03-07T06:43:18Z |
| format | Thesis |
| id | oxford-uuid:fa08301d-cd3d-4937-9315-2eb98d4f302e |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T06:43:18Z |
| publishDate | 2020 |
| record_format | dspace |
| spelling | oxford-uuid:fa08301d-cd3d-4937-9315-2eb98d4f302e2022-03-27T13:02:29ZCavity optomechanics with nm-thick membranesThesishttp://purl.org/coar/resource_type/c_db06uuid:fa08301d-cd3d-4937-9315-2eb98d4f302ePhysicsEnglishHyrax Deposit2020Pearson, ANBriggs, GADAres, N<p>This thesis focuses on fast and sensitive readout of mechanical motion to answer questions in the foundations of physics. By coupling a silicon nitride membrane to different readout cavities I have explored the thermodynamic costs of time keeping and carried out a bench-top experiment to put bounds on the theory of classical channel gravity. In order to reach these aims, I have developed real time displacement measurements of the motion of a nm-thick silicon nitride membrane. For this, a lumped element LC circuit is capacitively coupled to the metallized silicon nitride membrane. This approach allows for the estimation of key parameters without the need for frequency matching or cryogenic cooling. I demonstrate electromechanical characterization of several mechanical modes of the silicon nitride membrane. In addition, I show optomechanically induced transparency on chip in this high loss cavity.</p> <p>The real time displacement measurements of the membrane’s motion allow the device to be operated as a thermomechanical clock and to be used to investigate a thermodynamic trade-off in a nanoscale clock. The system follows a trade-off derived for the idealised quantum setting, indicating a fundamental universality of a relation previously predicted to hold in the quantum regime.</p> <p>This system is compatible with cryogenic temperatures, allowing me to actuate and detect the resonance frequency of a membrane at low temperatures. At these temperatures, one can perform tests of the theory of classical channel gravity which models the gravitational interaction as a classical measurement channel. The theory predicts a density dependent heating effect due to the gravitational interactions within the membrane itself. Bounds could be put on this theory using a membrane capacitively coupled to a 3D superconducting microwave cavity which has a much higher Q factor than the LC circuit. With this cavity, I achieved 10 mHz resolution of the mechanical signal, which is required for an accurate estimation of the mode temperature and thus to put bounds on the theory.</p> |
| spellingShingle | Physics Pearson, AN Cavity optomechanics with nm-thick membranes |
| title | Cavity optomechanics with nm-thick membranes |
| title_full | Cavity optomechanics with nm-thick membranes |
| title_fullStr | Cavity optomechanics with nm-thick membranes |
| title_full_unstemmed | Cavity optomechanics with nm-thick membranes |
| title_short | Cavity optomechanics with nm-thick membranes |
| title_sort | cavity optomechanics with nm thick membranes |
| topic | Physics |
| work_keys_str_mv | AT pearsonan cavityoptomechanicswithnmthickmembranes |