Observation of mechanical bound states in the continuum
Phonon trapping has raised widespread attention among researchers for its potential of various applications, such as microwave signal processing, interferometric gravitational wave detection and quantum mechanical oscillators. A common way to realize phonon trapping is through suspended structures as phonon transportation relies on medium and cannot permeate through the vacuum, yet it is mostly limited as complete isolation of the system from the environment is not achievable and detection of such systems is typically lagged by thermal capacity and excess noise. To circumvent these limitations, we propose a new cavity-less system based on bound states in the continuum (BICs), which are non-radiative states that can coexist with radiation waves inside the continuum region can oﬀer a platform for realizing phonon trapping without mechanical suspension. In-depth characterization of the acoustic loss mechanisms has been performed both at room temperature and cryogenic temperature. This new paradigm for phonon trapping, combining the macroscopic structure device and microwave frequency, has the potential for realizing the mechanical oscillators in both classical and quantum regimes, as well as the potential for high sensitivity sensing for rare-event searches and the exploration of the foundations of quantum mechanics in unreached parameter spaces.
Bound state in the continuum, Phononic crystal
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign