Imaging delocalized quasiparticles in the vortex state of NbSe₂

In a superconducting vortex lattice, delocalized quasiparticles escape the vortex cores where the order parameter vanishes. Tracing these delocalized quasiparticles is essential in understanding quasiparticle poisoning of Majorana bound states in vortex cores of a topological superconductor. Here, we image delocalized quasiparticles around vortices in NbSe₂, for the first time, with atomic resolution by scanning tunneling noise microscopy. From shot-noise imaging, we extract spatial variation of the effective charge when tunneling into the vortex state, which can be understood by the Ginzburg-Landau model. Furthermore, we find that quasiparticle poisoning dominates when vortices are less than 4 times the coherence length apart.