---

Electron quantum optics is a field aiming at the realization of photon experiments with flying electrons in nanostructures at the single-electron level [1, 2]. It is considered as an attractive platform to construct scalable quantum systems and a powerful tool to investigate the quantum nature of flying electrons. Necessary tools for such experiments are single-electron sources, single-electron detectors, beam splitters, phase shifters as well as controlled interaction between the electrons.
Recently our group as well as Cambridge group has demonstrated that a single electron can be transferred on-demand between distant quantum dots using a moving potential of surface acoustic waves (SAWs) [3, 4]. This operation formally corresponds to the realization of a single-electron source and a single-electron detector. To perform electron quantum optics experiments with such SAW flying electrons, development of other basic components such as a beam splitter and a phase shifter of the electrons is required.
In this seminar I will present recent experiments where we aim at the realization of a beam splitter as well as a phase shifter for SAW flying electrons. For that purpose we employ a tunnel-coupled wire, which was shown to work as a beam splitter for ballistic electrons [5]. We show that electron transfer across the tunnel-coupled wire can be highly efficient. Controlling the energy detuning of the tunnel-coupled wire allows us to realize a directional coupler for a single SAW flying electron by splitting the electrons into two paths with an arbitrary probability.

[1] E. Bocquillon et al., Science 339, 1054 (2013).
[2] J. Dubois et al., Nature 502, 659 (2013).
[3] S. Hermelin et al., Nature 477, 435 (2011).
[4] R. P. G. McNeil et al., Nature 477, 439 (2011).
[5] M. Yamamoto et al., Nature Nanotech. 7, 247 (2012).

---