  Single-electron sources on-demand are requisite for a promising fully
electronic platform for solid-state quantum information processing. Most of the
experimentally realized sources use the fact that only one electron can be
taken from a singly occupied quantum level. Here I take the next step and
discuss emission from orbitally degenerate quantum levels that arise, for
example, in quantum dots with a nontrivial ring topology. I show that
degeneracy provides additional flexibility for single- and two-electron
emission. Indeed, the small Aharonov-Bohm flux, which slightly lifts the
degeneracy, is a powerful tool for changing the relative width of the emitted
wave packets over a wide range. In a ring with one lead, even electrons emitted
from completely degenerate levels can be separated in time if the driving
potential changes at the appropriate rate. In a ring with two leads, electrons
can be emitted to different leads if one of the leads has a bound state with
Fermi energy at its end.
