Comment on “Vortex-assisted photon counts and their magnetic field dependence in single-photon superconducting detectors”

We discuss the importance of the vortex core energy and realistic boundary conditions to the Fokker-Plank equation for the calculation of thermally activated hopping of vortices across narrow superconducting films. Disregard of these issues in the papers by Bulaevskii, Graf and Kogan, Phys. Rev. B 85, 014505 (2012) and by Bulaevskii et al., Phys. Rev. B 83, 144526 (2011) in which an uncertain London vortex core cutoff was used, can produce large numerical errors and a significant discrepancy between their results and the results of the paper by Gurevich and Vinokur, Phys. Rev. Lett. 100, 227007 (2008) in which these issues were taken into account. This can be essential for the interpretation of experimental data on thin-film photon detectors and other superconducting nanostructures.