Quantum interference (QI), constructive (CQI) or destructive (DQI), which is naturally connected with molecular junctions, is an extremely important and novel phenomenon for nanoscience and nanotechnology, especially for molecular electronics. In contrast to the wellknown interference of light waves (or electrons) which takes place in real space, QI occurs in energy space when two electron pathways have similar energies and are in phase (CQI) or out of phase (DQI). Such pathways are typically created in molecular junctions through the interaction with the "anchors" which generates nearly degenerate frontier molecular orbitals (MOs), such as HOMOs (highest occupied MOs) and LUMOs (lowest unoccupied MOs), encompassing both the molecular linker and the anchors. In the present study an unusual new type of QI, in particular CQI, is revealed for isolated 13-AGNRs in which no external anchors are present, but a uniform electric field is applied along their longitudinal axis. Although AGNRs and other nanographenes (NGRs), or polycyclic aromatic hydrocarbons (PAHs), with bipartite (or alternant) topology have been used as linkers in molecular electronics studies, no isolated (free-standing) AGNRs or other graphene-based structures have been studied or used in connection with QI for obvious reasons, since QI is essentially created by the interaction with the anchor molecules. In all such cases it has been clearly shown that the bipartite (or alternant) topology is of dominant importance, since the conductance is extremely sensitive to connectivity i.e., to whether or not the connecting sites at the two ends belong to the same "sublattice". Likewise, recent work by the present author has illustrated that the bipartite topology, which is directly connected with "sublattice" (or pseudospin) symmetry frustration in AGNRs and other NGRs, is largely responsible for the generation of topological end-states localized at the zigzag ends of finite atomically precise AGNRs. In contrast to the common ("infinite") AGNRs synthesized with the usual topbottom procedure, topological end-states develop only to finite atomically precise AGNRs synthesized by bottom-up approach using molecular precursors grown on metallic and (recently) non-metallic 15-16 surfaces, to minimize substrate influence. It has been shown that such end-states are not grown gradually, but they appear suddenly as a "phase transition" at a critical length Lc especially for very narrow 5-AGNRs, whereas for wider 7and 9-AGNRs the transition is rather smooth 10 and practically unnoticed. Furthermore, it was recognized that such phase transition is also directly interconnected and associated with discontinuities in HOMO-LUMO gaps and aromaticity, on top of connectivity 7 and structure dependence, which for AGNRs enters through sublattice symmetry. This is like usual QI in molecular junctions. Nevertheless, no CQI or QI effects have ever been observed or expected for the isolated relatively "thin" AGNRs. To quantify the term "thin" we need to define the width W of the AGNRs in terms of the number of zigzag rings Z, W=2Z+1, where Z has been shown 9 to be of the form: