Split-Post Microwave Displacement Transducer with Quadratic Readout

Fuente: arXiv
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Hauptverfasser: Parashar, Sonali, Bourhill, Jeremy F., Goryachev, Maxim, Tobar, Michael E.
Format: Preprint
Veröffentlicht: 2026
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author Parashar, Sonali
Bourhill, Jeremy F.
Goryachev, Maxim
Tobar, Michael E.
author_facet Parashar, Sonali
Bourhill, Jeremy F.
Goryachev, Maxim
Tobar, Michael E.
contents We investigate a microwave cavity-based displacement readout employing a split-post geometry for measuring the motion of a dielectric membrane. The cavity response to membrane displacement is predominantly quadratic when the membrane is positioned at the centre of the posts. We characterise this behaviour by driving the membrane piezo electrically at both central and off-centre positions and calibrating the displacement using an independent interferometric measurement. The calibration reveals a linear coupling between the membrane displacement and the applied drive voltage, while the microwave response follows the static displacement dependence. When the membrane is driven at the centre, the system exhibits the highest displacement-to-voltage sensitivity and the largest quadratic output. As the membrane is moved away from the centre, the response gradually transitions from quadratic to linear. There is a difference of ~ 97 $\%$ in the quadratic coefficient from the central position and a difference of ~ 92 $\%$ in the linear coefficient from the off-centre position. This controllable crossover between quadratic and linear coupling is a key requirement for sensors capable of resolving energy quantisation. It establishes this platform as a promising candidate for a microwave-mechanical quantum transducer.
format Preprint
id arxiv_https___arxiv_org_abs_2602_07305
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Split-Post Microwave Displacement Transducer with Quadratic Readout
Parashar, Sonali
Bourhill, Jeremy F.
Goryachev, Maxim
Tobar, Michael E.
Instrumentation and Detectors
Applied Physics
Quantum Physics
We investigate a microwave cavity-based displacement readout employing a split-post geometry for measuring the motion of a dielectric membrane. The cavity response to membrane displacement is predominantly quadratic when the membrane is positioned at the centre of the posts. We characterise this behaviour by driving the membrane piezo electrically at both central and off-centre positions and calibrating the displacement using an independent interferometric measurement. The calibration reveals a linear coupling between the membrane displacement and the applied drive voltage, while the microwave response follows the static displacement dependence. When the membrane is driven at the centre, the system exhibits the highest displacement-to-voltage sensitivity and the largest quadratic output. As the membrane is moved away from the centre, the response gradually transitions from quadratic to linear. There is a difference of ~ 97 $\%$ in the quadratic coefficient from the central position and a difference of ~ 92 $\%$ in the linear coefficient from the off-centre position. This controllable crossover between quadratic and linear coupling is a key requirement for sensors capable of resolving energy quantisation. It establishes this platform as a promising candidate for a microwave-mechanical quantum transducer.
title Split-Post Microwave Displacement Transducer with Quadratic Readout
topic Instrumentation and Detectors
Applied Physics
Quantum Physics
url https://arxiv.org/abs/2602.07305