Figure 1
![Figure 1](http://media.springernature.com/full/springer-static/image/art%3A10.1140%2Fepjqt%2Fs40507-022-00139-w/MediaObjects/40507_2022_139_Fig1_HTML.jpg)
Electron flying qubit. (a) Bloch sphere showing the qubit state ψ that is defined via the tunnel-coupling θ and the phase shift ϕ. (b) Schematic of an electron two-path interferometer allowing precise adjustment of the qubit state via tunnel-coupling (Δθ) and the quantum phase (Δϕ) picked up along transport across the central island. (c) Transverse potential landscape across the tunnel-coupling region with schematic indications of the qubit basis 0 and 1. (d) Detailed 3D geometry of a quantum interferometer showing surface-gates (golden) defining the potential landscape and thus the transport paths in the two-dimensional electron gas (2DEG) located below the surface. The white crossed boxes indicate Ohmic contacts enabling electrical connection to the 2DEG. (e) Measurement of quantum oscillations as function of a perpendicular magnetic field B and the side-gate voltage \(V_{\mathrm{G}}\). Data adapted from Ref. [42]