Multitone Microwave Frequency Locking to a Noisy Cavity via Real-Time Feedback

Journal article (2023)

Authors

J. van Soest QN/Steele Lab - AS , Kavli institute of nanoscience Delft
C.A. Potts Kavli institute of nanoscience Delft, QN/Steele Lab - AS
S.R. Peiter Kavli institute of nanoscience Delft, QN/Steele Lab - AS
A. Sanz Mora QN/Steele Lab - AS , Kavli institute of nanoscience Delft
G.A. Steele QN/Steele Lab - AS , Kavli institute of nanoscience Delft
Research Group
QN/Steele Lab (AS) (TU Delft)
Copyright: © 2023 J. van Soest, C.A. Potts, S.R. Peiter, A. Sanz Mora, G.A. Steele
DOI: https://doi.org/10.1103/PhysRevApplied.20.034007
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Published Date

2023

Language

English

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Faculty

Applied Sciences

Department

QN/Quantum Nanoscience

Research Group

QN/Steele Lab

Abstract

Microwave cavities are commonly used in many experiments, including optomechanics, magnetic field sensing, magnomechanics, and circuit quantum electrodynamics. Noise, such as variations in the magnetic field or mechanical vibrations, can cause fluctuations of the natural frequency of the cavity, creating challenges in operating them in experiments. To overcome these challenges, we demonstrate a dynamic feedback system implemented by the locking of a microwave drive to the noisy cavity. A homodyne-interferometer scheme monitors the cavity resonance fluctuations due to low-frequency noise, which is mitigated by frequency modulating the microwave generator. The feedback has a bandwidth of 400 Hz, with a reduction of cavity fluctuations by 85% integrating up to a bandwidth of 2 kHz. Moreover, the cavity resonance frequency fluctuations are reduced by 73%. This scheme can be scaled to enable multitone experiments locked to the same feedback signal. As a demonstration, we apply the feedback to an optomechanical experiment and implement a cavity-locked multitone mechanical measurement. As low-frequency cavity frequency noise can be a limiting factor in many experiments, the multitone microwave locking technique presented here is expected to be relevant for a wide range of microwave-cavity experiments.