A four-panel paper figure: optical micrographs of a qubit chip (red outline) and a control chip (blue outline), each with a 2 mm scale bar, an oblique photograph of the two dies stacked face to face, and a circuit schematic. It comes from a 2023 arXiv paper by Chuan-Hong Liu et al. (University of Wisconsin-Madison, NIST, Syracuse University). It shows a single-flux-quantum digital driver chip bump-bonded to a two-transmon qubit chip, so control pulses are generated at millikelvin temperature beside the qubits; notice how closely the dies overlap.“Fig. 1(c) — Photograph of the assembled multichip module stack (qubit chip outlined red, SFQ chip outlined blue)” by Chuan-Hong Liu et al. (18 authors, Univ. Wisconsin–Madison, NIST, Syracuse Univ.), arxiv.org/abs/2301.05696, CC BY 4.0 (creativecommons.org/licenses/by/4.0/)
