ABSTRACT
This chapter gives an example of quantum kernels and the swap test. Then, it describes quantum kernels and the inversion test. Quantum feature maps encodes classical data into quantum data via a parametrized quantum circuit. A quantum computer can estimate a quantum kernel and the estimate can be used by a kernel method on a classical computer. This is because the exponential quantum advantage in evaluating inner products allows to estimate the quantum kernel machines directly in the higher-dimensional space. Quantum feature maps encodes classical data into quantum data via a parametrized quantum circuit. Quantum feature maps encodes classical data into quantum data via a parametrized quantum circuit that are hard to simulate classically and is an active area of current research.
