Phonon Engineering of Micro‐ and Nanophononic Crystals and Acoustic Metamaterials: A Review

Phononic crystals (PnCs) and acoustic metamaterials (AMMs) are artificially architected materials endowed with the capabilities of wave manipulation. This review specifically covers the theoretical fundamentals and recent development of PnCs and AMMs at the micro‐ and nanoscales due to their potential significance in modern electronic applications. Similarities and differences in phonon transport at these two scales are discussed. Research gaps between the macro‐ and small‐scale PnC and AMM development are identified from a theoretical point of view. A future outlook is also presented to propose possible applications of micro‐ and nano‐PnCs and AMMs, including advancing quantum information processing technologies, such as quantum computing.