Quantum Gyroscopes with Nonreciprocity Enhance Sensitivity at Single-Phonon Levels Using Surface Acoustic Waves

For decades, surface acoustic waves have formed the basis of gyroscope technology, but their effectiveness is now reaching fundamental limits when applied to increasingly complex navigation challenges. Y. T. Zhu, Shibei Xue, Fangfang Ju, and Haidong Yuan investigate a new approach to overcome these limitations by harnessing the unique properties of quantized surface acoustic waves. Their work demonstrates that designing gyroscopes with multiple connection points between waves introduces a directionality, known as nonreciprocity, that dramatically improves performance. This nonreciprocal transfer enhances the signal-to-noise ratio and sensitivity, allowing for the detection of signals previously hidden within noise, and ultimately paving the way for more accurate and robust navigation technologies.

Nonreciprocity enhanced Quantum Gyroscopes based on Surface Acoustic Waves Researchers are investigating quantum gyroscopes that utilize surface acoustic waves to achieve greater sensitivity through nonreciprocal signal propagation. This approach manipulates acoustic waves to create a directional dependence in the gyroscope’s response, amplifying the signal generated by rotation. The team carefully engineers the acoustic pathway to favour wave travel in one direction, a principle known as nonreciprocity, demonstrating improved performance over conventional designs. The findings pave the way for developing highly accurate and robust quantum gyroscopes for applications in navigation, robotics, and other demanding fields.

Quantized Surface Acoustic Wave Resonator Fabrication

Surface acoustic waves, or SAWs, have been used in gyroscopes for over 40 years, but their traditional working principle is becoming less effective for modern sensing challenges. Recent advancements in quantized SAWs offer a promising solution, enabling operation at extremely low power levels. The team fabricated a piezoelectric resonator on lithium niobate to generate and detect these quantized SAWs, incorporating a metallic strip to confine acoustic energy and enhance interaction with microwave signals. The device is cooled to cryogenic temperatures to reduce thermal noise and improve the signal-to-noise ratio. Microwave signals are applied to the resonator, and the resulting SAWs are precisely controlled and monitored. By analysing changes in the microwave signal, the team detects the presence and characteristics of the quantized SAWs, demonstrating a new approach to acoustic sensing through measurement of the resonator’s resonance frequency and quality factor.

Hybrid Quantum-Acoustic Rotation Sensing Demonstrated

This research focuses on enhancing rotation sensing through the development of hybrid quantum-acoustic systems. The core principle involves combining giant atoms, created using superconducting circuits, with surface acoustic waves to create a strong coupling between quantum and mechanical degrees of freedom. This hybridization, coupled with non-reciprocal elements, enhances sensitivity to rotation, leveraging cavity optomechanics, waveguide quantum electrodynamics, and the SLH framework to explore new physical mechanisms for improved performance. Giant atoms, realized using superconducting circuits, offer strong light-matter interaction and are coupled to SAWs to mediate interactions and enhance sensitivity. The team investigates acoustic resonators to amplify signals and employs non-reciprocal elements to break symmetry and isolate signals from noise. Theoretical frameworks, including the SLH framework, are used to analyse quantum input-output networks and understand quantum noise, exploring concepts such as atom-light hybrid systems and single-photon sensing to further improve sensor performance.

Nonreciprocal Gyroscope Detects Earth’s Rotation

This research presents a novel gyroscope design based on quantized surface acoustic waves, offering a pathway towards significantly enhanced sensitivity and performance. By utilizing multiple coupling points within a system of giant cavities, the team demonstrated that the resulting non-Markovian dynamics induce nonreciprocal transfer, a previously unobserved phenomenon. This nonreciprocity fundamentally improves the signal-to-noise ratio and sensitivity, enabling the detection of extremely slow rotations, potentially even the Earth’s self-rotation. Importantly, the team highlights that the observed non-Markovian behavior is an inherent property of these quantum systems, invalidating the common Markovian approximation often used in similar analyses, establishing a foundation for future advancements in precision sensing technologies.