11.3 Quantum cores and interconnects
However you build or trap objects that behave like physical qubits, there is a maximum number of qubits that you can put in a device and reliably control. Even if you could put more, there may be other factors that put an upper bound on the qubit capacity. Larger semiconductor chips, for example, are difficult to manufacture, and any flaws could spoil the chips and decrease yield. quantum$core
I call such a unit with a fixed number of qubits a quantum core. These units are analogous to the multiple cores in classical processing units. For example, my desktop computer has an AMD processor with 12 cores. Figure 11.2 is a diagram that helps us visualize a quantum core with 16 qubits.
I chose 16 as a convenient number of qubits to illustrate the concepts in this section. Industry vendors have demonstrated cores with several dozen to several...
