  Free-electron interactions with laser-driven nanophotonic nearfields can
quantize the electrons' energy spectrum and provide control over this quantized
degree of freedom. We propose to use such interactions to promote free
electrons as carriers of quantum information and find how to create a qubit on
a free electron. We find how to implement the qubit's non-commutative
spin-algebra, then control and measure the qubit state with a universal set of
1-qubit gates. These gates are within the current capabilities of
femtosecond-pulsed laser-driven transmission electron microscopy. Pulsed laser
driving promise configurability by the laser intensity, polarizability, pulse
duration, and arrival times.

Quantum Physics