Femtotechnology is used to structure matter on the scale of a femtometer, which is 10−15 m. This is a smaller scale in comparison with nanotechnology and picotechnology which refer to 10−9 m and 10−12 m respectively.
This involves manipulation of excited energy states within atomic nuclei, specifically nuclear isomers, to produce metastable states with unusual properties. In the extreme case, excited states of the individual nucleons that make up the atomic nucleus are used to tailor the behavioral properties of these particles.
'Femtoengineering' at this scale involves working directly with the finest known structures of matter such as quarks, Q-balls and strings to manipulate the properties of atoms. This development is a further step towards the teleportation of objects visible to the naked eye. Significant breakthroughs in force field generation and anti-gravity might benefit from it as well.
This is a massive breakthrough in materials technology. Metals will be produced which are capable of withstanding enormous pressures and heat. For example, we could create probes capable of traveling into the Sun and tunneling machines that can penetrate the Earth's crust into the layers of magma beneath. Longer-term, this development will pave the way for interstellar ships that can withstand the massive forces involved in lightspeed travel.
Other more exotic materials become possible including transparent metals, highly luminous metals, frictionless surfaces, and ultra-dense but extremely lightweight structures. Femtoengineering could be guided and by advanced AIs, which are now trillions upon trillions of times more powerful than human intelligence.
Additionally, this technology will enable self-replicating nanobots to replace any type of matter imaginable (including biological organisms) and spread throughout any area relatively quickly. This is an effective way to infuse any environment with computronium, which is a form of programmable matter that can perform computation, that users can wirelessly control.