Topological nanophononic states by band inversion

Martin Esmann,Fabrice Roland Lamberti,Olivier Krebs,Norberto Daniel Lanzillotti-Kimura,Carmen Gomez Carbonell,Pascale Senellart,Loïc Lanco,Aristide Lemaître,Ivan Favero

doi:10.1103/physrevb.97.155422

Abstract

Nanophononics is essential for the engineering of thermal transport in nanostructured electronic devices, it greatly facilitates the manipulation of mechanical resonators in the quantum regime, and could unveil a new route in quantum communications using phonons as carriers of information. Acoustic phonons also constitute a versatile platform for the study of fundamental wave dynamics, including Bloch oscillations, Wannier Stark ladders and other localization phenomena. Many of the phenomena studied in nanophononics were indeed inspired by their counterparts in optics and electronics. In these fields, the consideration of topological invariants to control wave dynamics has already had a great impact for the generation of robust confined states. Interestingly, the use of topological phases to engineer nanophononic devices remains an unexplored and promising field. Conversely, the use of acoustic phonons could constitute a rich platform to study topological states. Here, we introduce the concept of topological invariants to nanophononics and experimentally implement a nanophononic system supporting a robust topological interface state at 350 GHz. The state is constructed through band inversion, i.e. by concatenating two semiconductor superlattices with inverted spatial mode symmetries. The existence of this state is purely determined by the Zak phases of the constituent superlattices, i.e. that one-dimensional Berry phase. We experimentally evidenced the mode through Raman spectroscopy. The reported robust topological interface states could become part of nanophononic devices requiring resonant structures such as sensors or phonon lasers.

Highlights

In macroscopic acoustics exciting effects such as acoustic cloaking [1,2], superlensing [3], traps for electrons [4], and rainbow trapping [5] have recently been reported
Nanophononics is essential for the engineering of thermal transport in nanostructured electronic devices, it greatly facilitates the manipulation of mechanical resonators in the quantum regime, and it could unveil a new route in quantum communications using phonons as carriers of information
Phonon engineering in the gigahertz-to-terahertz range has major implications in other domains: in optomechanics for the manipulation of mechanical resonators in their quantum ground state [10,11], in electronics for determining the thermal transport properties of nanostructured devices [8,12,13], and even in solid-state quantum communications, where acoustic phonons could serve as carriers of quantum information [14,15,16] interfacing quantum bits based on different solid-state platforms [17,18]

Summary

Introduction

In macroscopic acoustics exciting effects such as acoustic cloaking [1,2], superlensing [3], traps for electrons [4], and rainbow trapping [5] have recently been reported. Nanophononics, relying on the same wave mechanics, addresses the engineering and manipulation of high-frequency phonons at the nanoscale [6,7,8,9]. Phonon engineering in the gigahertz-to-terahertz range has major implications in other domains: in optomechanics for the manipulation of mechanical resonators in their quantum ground state [10,11], in electronics for determining the thermal transport properties of nanostructured devices [8,12,13], and even in solid-state quantum communications, where acoustic phonons could serve as carriers of quantum information [14,15,16] interfacing quantum bits based on different solid-state platforms [17,18].

Methods

Results

Conclusion