A quantum circuit consisting of parameterized gates RX(theta), RY(theta) and RZ(theta), represents a unitary transformation \(U(\theta)\) that transforms the initial quantum state into an Ansatz state \(|\psi(\theta)\rangle\).
Hardware Efficient Ansatz#
Qibochem provides a hardware efficient ansatz that simply consists of a layer of single qubit rotation gates followed by a layer of two-qubit gates that entangle the qubits. For the H2 case discussed in previous sections, a possible hardware efficient ansatz can be constructed as such:
Placeholder for hardware-efficient ansatz example
Unitary Coupled Cluster Ansatz#
The Unitary Coupled Cluster ansatz   is a variant of the popular gold standard Coupled Cluster ansatz  of quantum chemistry. The unitary coupled cluster wave function is a parameterized unitary transformation of a reference wave function, of which a common choice is the Hartree-Fock wave function.
Placeholder for UCCD example