Role of quasiparticle scattering in Gray's superconducting transistor

We report the results of detailed numerical simulations of Gray's transistor mechanism [Appl. Phys. Lett. 32, 392 (1978)]. These calculations, carried out using two different approaches, show that the energy scattering of quasiparticles is very important in achieving gain such as Gray reported. When this scattering is included, we find that gain is possible, not only in aluminum, but also in niobium and tantalum.