Non-thermal response of a diffusion-cooled hot-electron bolometer

We present analysis of a diffusion-cooled hot-election bolometer in the lim iting case of a weak thermalization of non-equilibrium quasiparticles. We p ropose a new model replying on the non-thermal suppression of the supercond ucting energy gap by excess quasiparticles. Using material parameters typic al for Al, we evaluate performance of the bolometer in the heterodyne regim e at terahertz frequencies. Estimates show that the miser may have quantum limited noise temperature and a few tens of GHz bandwidth, while the requir ed local oscillator power is in the mu W range due to in-effective suppress ion of the energy gap by quasiparticles with high energies.