One chip, five layers
Scroll to take apart the reference stack this framework proposes for a room-temperature quantum processor: silicon does the heavy classical work, and a diamond chiplet on top carries the qubits and the transistors that read them.
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A normal computer chip sits at the bottom and does the thinking it is good at. On top sits a thin slice of diamond with the special quantum spots in it. Light shines down from above to reset them, and tiny wires read them out.
Heterogeneous integration: each material does what it does best. Silicon CMOS supplies microwave synthesis, amplification, and decoding; the diamond chiplet supplies qubits, rugged interface transistors, and heat spreading. The two are bonded face to face.
This is the chapter 9 proposal. Chiplet-on-CMOS integration has been demonstrated for diamond color centers [li2024]; electrical readout replaces the objective lens [siyushev2019]; the cluster pitch and cell counts for a full machine are sized in chapter E10.
Sources: [li2024] [wan2020] [kim2019cmos] [siyushev2019] [balasubramanian2009] [acosta2010]