The wave-particle duality of the qudit-based quantum space is demonstrated by
the wave-like quantum functionals and the particle-like quantum states. The
quantum functionals are quantum objects generated by the basis qudit
functionals, which are the duals of the basis qudit states. The relation
between the quantum states and quantum functionals is analogous to the relation
between the position and momentum in fundamental quantum physics. In
particular, the quantum states and quantum functionals are related by a Fourier
transform, and the quantum functionals have wave-like interpretations. The
quantum functionals are not just mathematical constructs but have clear
physical meanings and quantum circuit realizations. Any arbitrary qudit-based
quantum state has dual characters of wave and particle, and its wave character
can be evaluated by an observable and realized by a quantum circuit