Add Projected Kernels and Hamiltonian Evolution Feature Maps

[OkuyanBoga]

• A feature map based on Hamiltonian evolution as described in [1]

$$ |\Psi_0\rangle = \bigotimes_{j=1}^{n+1} |\psi_j\rangle $$

$$ U_{\text{EVO}}(\vec{x}) = \prod_{j=1}^{n} e^{-ix_j(X_jX_{j+1} + Y_jY_{j+1} + Z_jZ_{j+1})} $$

• Projected Kernels as described in [1]

[1] Huang, Hsin-Yuan, et al. "Power of data in quantum machine learning." Nature Communications 12.1 (2021): 2631.