An electrical filter includes a dielectric substrate with inner and outer coils about a first region and inner and outer coils about a second region, a portion of cladding removed from wires that form the coils and coupled to electrically conductive traces on the dielectric substrate via a solder joint in a switching region. An apparatus to thermally couple a superconductive device to a metal carrier with a through-hole includes a first clamp and a vacuum pump. A composite magnetic shield for use at superconductive temperatures includes an inner layer with magnetic permeability of at least 50,000; and an outer layer with magnetic saturation field greater than 1.2 T, separated from the inner layer by an intermediate layer of dielectric. An apparatus to dissipate heat from a superconducting processor includes a metal carrier with a recess, a post that extends upwards from a base of the recess and a layer of adhesive on top of the post. Various cryogenic refrigeration systems are described.