Superconductor thermal filter

A superconductor thermal filter comprising:

• a normal metal layer having a first side and a second side;
• an insulating layer overlying the first side of the normal metal layer;
• a multilayer superconductor structure having a first side overlying a side of the insulating layer opposite the side that overlies the normal metal layer, the multilayer superconductor structure comprised of a plurality of superconductor layers with each superconductor layer having a smaller superconducting energy band gap than the preceding superconductor as the superconductor layers extend away from the normal metal layer;
• and
• a normal metal layer quasiparticle trap having a first side and a second side, the first side being disposed on a second side of the multilayer superconductor structure;
• wherein a bias voltage is applied between the normal metal layer and the normal metal layer quasiparticle trap to remove hot electrons from the normal metal layer through each superconductor layer of the multilayer superconductor structure to the normal metal layer quasiparticle trap.