  Quantized nano-objects offer a myriad of exciting possibilities for
manipulating electrons and light that impact photonics, nanoelectronics, and
quantum information. In this context, ultrashort laser pulses combined with
nanotips and field emission have permitted renewing nano-characterization and
control electron dynamics with unprecedented space and time resolution reaching
femtosecond and even attosecond regimes. A crucial missing step in these
experiments is that no signature of quantized energy levels has yet been
observed. We combine in situ nanostructuration of nanotips and ultrashort laser
pulse excitation to induce multiphoton excitation and electron emission from a
single quantized nano-object attached at the apex of a metal nanotip.
Femtosecond induced tunneling through well-defined localized confinement states
that are tunable in energy is demonstrated. This paves the way for the
development of ultrafast manipulation of electron emission from isolated
nano-objects including stereographically fixed individual molecules and high
brightness, ultrafast, coherent single electron sources for quantum optics
experiments.
