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Telecommunication of the next generation demands filters that can operate in the 10 GHz range with sufficient bandwidths. For surface-acoustic-wave (SAW) devices this prerequisite translates into high sound velocities and high piezoelectric couplings. Wurtzite AlN on diamond, which exploits the strong piezoelectricity of AlN with the very high SAW velocity of diamond, has been considered a promising platform. A significant boost (up to a factor of 4) of the piezoelectric response can be obtained by alloying AlN with Sc. Here, the main challenge lies in the synthesis of highly-oriented thin (Sc,Al)N films on diamond. In this work, we aim at establishing a platform for SAW devices using plasma-assisted molecular beam epitaxy for the deposition of Sc0.2Al0.8N on diamond. We investigate the structural properties related to SAW generation gearing towards applications at high frequencies. To this end, we prepare (Sc,Al)N thin films on polished polycrystalline diamond wafers and demonstrate the efficient generation of SAW modes with frequencies up to 8 GHz. Systematic studies of the dependence of the SAW velocity and electromechanical coupling coefficient on the Sc0.2Al0.8N film thickness is presented for various SAW modes. Our result demonstrates the potential of this material combination for future application that requires large bandwidth in the ultra-high frequency range. [ABSTRACT FROM AUTHOR]

An important prerequisite for quantum communication networks is the transfer and manipulation of single particles on a chip as well as their interconversion to single photons for long-range information exchange. GHz acoustic waves are versatile tools for the implementation of these functionalities in hybrid quantum systems. In particular, flying excitons propelled by GHz surface acoustic waves (SAWs) can potentially satisfy this prerequisite. In this article, we review recent works on the application of GHz SAWs to realize flying excitons in semiconductor-based systems. Most importantly, we have identified suitable two-level centers for the storage of single excitons, thus forming single excitonic qubits, and interconverted them to single photons with a very high emission rate dictated by the GHz-SAW pumping. The work covered here paves the way for on-chip, exciton-based qubit manipulation. [ABSTRACT FROM AUTHOR]

We report the operation of a radio frequency superconducting single-electron transistor (rf-SSET) as a charge sensor for single and double Si/SiGe quantum dots (QDs). Real-time electron tunneling events are observed from the reflected signal of the rf-SSET with a charge sensitivity of [formula], which demonstrates a fast charge detection time of a few tens of microseconds. Measurements of the reflected power are used to map out the stability diagram of the double quantum dot. [ABSTRACT FROM AUTHOR]