8.3 Quantum-classical models
In general terms, quantum machine learning refers to the application of machine learning techniques — only that quantum computing is involved at same stage of the process. Maybe you use a quantum computer in some part a model that you wish to train. Maybe you wish to use data generated by some quantum process. Maybe you use a quantum computer to process quantum-generated data. As you can imagine, the subject of quantum machine learning, as a whole, is broad enough to accommodate for a wide range of ideas and applications.
In an attempt to categorize it all a little bit, we can follow the useful classification shown in Schuld’s and Petruccione’s book [106] and divide quantum machine learning into four different flavors, which are depicted in Figure 8.6, according to the classical or quantum nature of the data and processing devices that are used:
We could consider part of quantum machine learning all the quantum-inspired classical machine...
