Coherent XUV generation driven by sharp metal tips photoemission

It was already experimentally demonstrated that high-energy electrons can be generated using metal nanotips as active non-linear media. In addition, it has been theoretically proven that the high-energy tail of the photoemitted electrons is intrinsically linked to the so-called recollision phenomenon. Through this recollision process it is also possible to convert the energy gained by the laser-emitted electron in the continuum in a coherent XUV photon. This means the emission of harmonic radiation appears to be feasible, although it has not been experimentally demonstrated hitherto. In this paper, we employ a quantum mechanical approach to model the electron dipole moment including both the laser experimental conditions and the bulk matter properties in order to predict it is possible to generate coherent UV and XUV radiation using metal nanotips as sources. Our quantum mechanical results are fully supported by their classical counterparts.