Once the quantum computing circuit 5 has been formed on the substrate 2, the elements of the quantum computing circuit 5 are connected to off-chip wiring that is used to control the computations performed by the quantum computing circuit 5. The substrate 2 is inserted into the recess 10 in the holder 3 so that it sits on the upper surface 9 of the holder 3 with the projections 12 passing through the thickness of the substrate. The cover 4 is placed over the top of, and thus enclosing, the substrate 2, such that the projections 12 contact the underside of the cover 4 via the volumes of indium 18 in the depressions 16 in the underside of the cover 4. The off-chip control wiring is passed through the apertures 13, 14 in the holder 3 and the cover 4 and suitably connected to control circuitry.

The superconducting quantum computing circuit package 1 is placed into a suitable cryogenic system, to enable its operation at a superconducting temperature.