The law of reciprocity in acoustics and elastodynamics codifies a relation of symmetry
between action and reaction in fluids and solids. In its simplest form, it states that the …

Reciprocity is a general, fundamental principle governing various physical systems, which
ensures that the transfer function—the transmission of a physical quantity, say light intensity …

Breaking acoustic reciprocity is essential to create robust one-way propagation where sound
waves or elastic vibrations are permitted to travel in only one direction. This unidirectional …

Unidirectional devices that pass acoustic energy in only one direction have numerous
applications and, consequently, have recently received significant attention. However, for …

Mechanical motion can break the symmetry in which sound travels in a medium, but
significant nonreciprocity is typically achieved only for large motion speeds. We combine …

Systems that break reciprocity offer new possibilities for controlling wave propagation. Here
we study the scattering properties of coupled resonator systems that are under dynamic …

In linear, lossless, time-invariant, and nonbiased acoustic systems, mode transitions are time
reversible, consistent with Lorentz reciprocity and implying a strict symmetry in space-time …

Acoustic waves in a linear time-invariant medium are generally reciprocal; however,
reciprocity can break down in a time-variant system. In this Letter, we report on an …

The primary objective of acoustic metamaterial research is to design subwavelength
systems that behave as effective materials with novel acoustical properties. One such …

Elastic waveguides with time-modulated stiffness feature a frequency-periodic dispersion
spectrum, where branches merge at multiple integers of half the modulation frequency and …