System and method for generating a quantum circuit

Concepts, systems and methods are described for generating a quantum circuit from a Unitary Coupled Cluster (UCC) ansatz which represents the excitation of a reference state by a parameterised operator including excitation operators. The UCC ansatz includes multi-qubit Pauli operators, referred to as Pauli strings, determined from each excitation operator. The method comprises partitioning the Pauli strings into mutually commuting sets and sequencing the Pauli strings by set. Pauli gadgets are then generated from the Pauli strings by Trotterization, the Pauli gadgets having the same sequencing by set as the Pauli strings. Each set of Pauli gadgets is diagonalised to convert the Pauli gadgets into phase gadgets which are then transformed into one- and two-qubit native gates to generate the quantum circuit.