Observation of phonon trapping in the continuum with topological charges

TL;DR

This paper demonstrates a novel phonon trapping method using topological bound states in the continuum, offering a new platform for advanced mechanical oscillators with potential quantum and sensing applications.

Contribution

It introduces mechanical BICs with topological features as a new paradigm for phonon trapping, overcoming limitations of traditional suspension methods.

Findings

Mechanical BICs operate at microwave frequencies and macroscopic sizes.

Characterization of mechanical losses at room and cryogenic temperatures.

Potential for quantum regime applications and advanced sensing modalities.

Abstract

Phonon trapping has an immense impact in many areas of science and technology, from the antennas of interferometric gravitational wave detectors to chip-scale quantum micro- and nano-mechanical oscillators. It usually relies on the mechanical suspension--an approach, while isolating selected vibrational modes, leads to serious drawbacks for interrogation of the trapped phonons, including limited heat capacity and excess noises via measurements. To circumvent these constraints, we realize a new paradigm of phonon trapping using mechanical bound states in the continuum (BICs) with topological features and conducted an in-depth characterization of the mechanical losses both at room and cryogenic temperatures. Our findings of mechanical BICs combining the microwave frequency and macroscopic size unveil a unique platform for realizing mechanical oscillators in both classical and quantum regimes. The paradigm of mechanical BICs might lead to unprecedented sensing modalities for applications such as rare-event searches and the exploration of the foundations of quantum mechanics in unreached parameter spaces.