9.1 So many gates

In practice, a hardware quantum computer implements a core set of primitive gates, and we construct the others using circuits of the primitives. These core operations may be among the ones we saw in the last chapter, or they may be much stranger looking: you can consider any 2-by-2 unitary matrix a 1-qubit gate.

The primitive gates depend on the technology used to create the physical quantum computer. We construct more advanced gates from these primitive gates. For example, the Qiskit and Cirq open-source quantum computing frameworks provide a large selection of gates you can use. 42 181 Qiskit Cirq

At the hardware level, experimental physicists and engineers work to optimize the core gates. Above that, other physicists and computer scientists try to create the best-performing higher-level gates.

In the classical case, machine code is extremely low-level and directly instructs the processor. Above that is assembly code, which abstracts...