The Schwarzschild radius of a black hole is a classical barrier for light from inside of a black hole. But we know from electromagnetic waves and quantum mechanics that classical barriers can be crossed/tunneled, because on the other side of the barrier a so called https://en.wikipedia.org/wiki/Evanescent_field exists. Does such a field also exist at the Schwarzschild surface? If yes couldn't we, e.g. by bringing another mass close (in the order of a few wavelength of the light) to the Schwarzschild surface, extract light out of the black hole again (analogous to Frustrated total internal reflection)?
Theoretically it is actually possible. If you take the Schrodinger's equation and in the place of potential if you place the Newton's gravitational potential for the system you are talking about you can find out the tunneling constant. You will find out that the tunneling probability is inversely proportional to the exponential of the height and the length of the barrier.