To calculate a current named for this phenomenon, John Bardeen used a time-dependent perturbation in his transfer Hamiltonian method. Fowler and Nordheim modeled field emission using this phenomenon, which causes Esaki diodes to (10[1])exhibit a negative differential resistance. In a Nobel-Prize-winning device developed by Binning and Rohrer, electrons undergo this phenomenon to induce a current in a conducting microscope tip. In an alpha decay theory posited by George Gamow, helium nuclei undergo this phenomenon to escape Coulombic interactions, meaning there is a nonzero wavefunction outside of a finite square well. For 10 points, name this quantum phenomenon where a particle passes through (10[1])a classically forbidden barrier. ■END■