Acoustic versus electromagnetic field theory: scalar, vector, spinor representations and the emergence of acoustic spin
Year: 2020
Type: article
Abstract: We construct a novel Lagrangian representation of acoustic field theory that describes the local vector properties of longitudinal (curl-free) acoustic fields. In particular, this approach accounts for the recently-discovered nonzero spin angular momentum density in inhomogeneous sound fields in fluids or gases. The traditional acoustic Lagrangian representation with a scalar potential is unable to describe such vector properties of acoustic fields adequately, which are however observable via local radiation forces and torques on small probe particles. By introducing a displacement vector potential analogous to the electromagnetic vector potential, we derive the appropriate canonical momentum and spin densities as conserved Noether currents. The results are consistent with recent theoretical analyses and experiments. Furthermore, by an analogy with dual-symmetric electromagnetic field theory that combines electric- and magnetic-potential representations, we put forward an acoustic spinor representation combining the scalar and vector representations. This approach also includes naturally coupling to sources. The strong analogies between electromagnetism and acoustics suggest further productive inquiry, particularly regarding the nature of the apparent spacetime symmetries inherent to acoustic fields.
Source: New Journal of Physics
Institutions: Chapman University, RIKEN, University of Michigan
Language: English
Subfield: Acoustics and Ultrasonics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,610
Funders: National Science Foundation, Foundational Questions Institute, National Institute of Advanced Industrial Science and Technology, Asian Office of Aerospace Research and Development, Russian Foundation for Basic Research, Fonds Wetenschappelijk Onderzoek, Multidisciplinary University Research Initiative, Japan Society for the Promotion of Science, Japan Science and Technology Agency, RIKEN, Core Research for Evolutional Science and Technology, Air Force Office of Scientific Research, Army Research Office
Awards: G1429566569, G1523888516, NSF-BSF: Efficiently Modeling Continuous Quantum Measurements of High-Dimensional Multi-Qubit Systems, G1812050430, G2365865096, G2490340067, G3138503318, G3591598716, G4166571500, G4185520633, G4403483161, G4555662530, G4562773702, G5032336395, G588291333, G6417840507, G649830273, G7452299184, G7791462391, 超伝導人工原子を使った光子ベースの量子情報処理, G8224071431, G88303486, G8883783173, 小形歯車の噛合試験機の試作研究, G957415934, G962039800
OpenAlex ID: W3011166076