Electrons confined to one dimension exhibit various counter-intuitive phenomena such as charge fractionalization, spin-charge separation, and Majorana end modes induced at nanowires rendered topologically superconducting. We perform spectroscopic mappings of the electronic states in semiconducting InAs nanowires through scanning tunneling microscopy. We identify two novel effects driven by the strong electron-electron interactions. The First effect is a new energy regime of regained phase coherence of hot electrons  [1]. The origin of this unusual energy-evolution of phase coherence lies in the form of the effective Coulomb interaction in one-dimension that increasingly decouples the hot electrons from the cold Fermi sea.  The second effect is an indirect coulomb blockade-like mechanism where in-gap resonances act as a switch for the conductance of the one-dimensional states [2]. The interaction between the resonances and the continuum is mediated by quantum dots that naturally form both in the gold droplets used to catalyze the nanowire growth as well as in aluminum droplets epitaxially grown on the nanowire side facets. The detection of these phenomena is enabled by maintaining the MBE grown nanowires under ultra-high vacuum. This procedure uniquely allows us to atomically resolve the pristine facets of the nanowires, to detect the electronic quantized spectrum through Van Hove singularities and to visualize the quantized subbands through the interference patterns the one dimensional electronic states embed in the local density of states as they scatter off adatoms, stacking faults and the nanowire end. This technology paves the way for the study of additional exotic phenomena in one dimensional nanowires such as induced topological superconductivity and Majorana end modes therein.

[1] PRX 7 (2017) 021016

[2] under preparation