2019, Delsing, Per, Cleland, Andrew N., Schuetz, Martin J.A., Knörzer, Johannes, Giedke, Géza, Cirac, J. Ignacio, Srinivasan, Kartik, Wu, Marcelo, Balram, Krishna Coimbatore, Bäuerle, Christopher, Meunier, Tristan, Ford, Christopher J.B., Santos, Paulo V., Cerda-Méndez, Edgar, Wang, Hailin, Krenner, Hubert J., Nysten, Emeline D.S., Weiß, Matthias, Nash, Geoff R., Thevenard, Laura, Gourdon, Catherine, Rovillain, Pauline, Marangolo, Max, Duquesne, Jean-Yves, Fischerauer, Gerhard, Ruile, Werner, Reiner, Alexander, Paschke, Ben, Denysenko, Dmytro, Volkmer, Dirk, Wixforth, Achim, Bruus, Henrik, Wiklund, Martin, Reboud, Julien, Cooper, Jonathan M., Fu, YongQing, Brugger, Manuel S., Rehfeldt, Florian, Westerhausen, Christoph

Today, surface acoustic waves (SAWs) and bulk acoustic waves are already two of the very few phononic technologies of industrial relevance and can been found in a myriad of devices employing these nanoscale earthquakes on a chip. Acoustic radio frequency filters, for instance, are integral parts of wireless devices. SAWs in particular find applications in life sciences and microfluidics for sensing and mixing of tiny amounts of liquids. In addition to this continuously growing number of applications, SAWs are ideally suited to probe and control elementary excitations in condensed matter at the limit of single quantum excitations. Even collective excitations, classical or quantum are nowadays coherently interfaced by SAWs. This wide, highly diverse, interdisciplinary and continuously expanding spectrum literally unites advanced sensing and manipulation applications. Remarkably, SAW technology is inherently multiscale and spans from single atomic or nanoscopic units up even to the millimeter scale. The aim of this Roadmap is to present a snapshot of the present state of surface acoustic wave science and technology in 2019 and provide an opinion on the challenges and opportunities that the future holds from a group of renown experts, covering the interdisciplinary key areas, ranging from fundamental quantum effects to practical applications of acoustic devices in life science. © 2019 IOP Publishing Ltd.

2018, Weiß, Matthias, Hörner, Andreas L., Zallo, Eugenio, Atkinson, Paola, Rastelli, Armando, Schmidt, Oliver G., Wixforth, Achim, Krenner, Hubert J.

Wide-passband interdigital transducers are employed to establish a stable phase lock between a train of laser pulses emitted by a mode-locked laser and a surface acoustic wave generated electrically by the transducer. The transducer design is based on a multiharmonic split-finger architecture for the excitation of a fundamental surface acoustic wave and a discrete number of its overtones. Simply by introducing a variation of the transducer's periodicity p, a frequency chirp is added. This combination results in wide frequency bands for each harmonic. The transducer's conversion efficiency from the electrical to the acoustic domain is characterized optomechanically using single quantum dots acting as nanoscale pressure sensors. The ability to generate surface acoustic waves over a wide band of frequencies enables advanced acousto-optic spectroscopy using mode-locked lasers with fixed repetition rate. Stable phase locking between the electrically generated acoustic wave and the train of laser pulses is confirmed by performing stroboscopic spectroscopy on a single quantum dot at a frequency of 320 MHz. Finally, the dynamic spectral modulation of the quantum dot is directly monitored in the time domain combining stable phase-locked optical excitation and time-correlated single-photon counting. The demonstrated scheme will be particularly useful for the experimental implementation of surface-acoustic-wave-driven quantum gates of optically addressable qubits or collective quantum states or for multicomponent Fourier synthesis of tailored nanomechanical waveforms.