  We develop a coherent beam splitter for single electrons driven through two
tunnel-coupled quantum wires by surface acoustic waves (SAWs). The output
current through each wire oscillates with gate voltages to tune the
tunnel-coupling and potential difference between the wires. This oscillation is
assigned to coherent electron tunneling motion that can be used to encode a
flying qubit and is well reproduced by numerical calculations of time evolution
of the SAW-driven single electrons. The oscillation visibility is currently
limited to about 3%, but robust against decoherence, indicating that the
SAW-electron can serve as a novel platform for a solid-state flying qubit.
