System and method for generating a quantum circuit

A system comprising at least one processor and a compiler configured to run on the processor to generate a quantum circuit from a Unitary Coupled Cluster (UCC) ansatz which represents an excitation of a reference state by a parameterised operator including excitation operators, the UCC ansatz including multi-qubit Pauli operators, referred to as Pauli strings, determined from each excitation operator, the compiler being configured to:

• partition the Pauli strings into mutually commuting sets and sequencing the Pauli strings by set;
• generate Pauli gadgets from the Pauli strings by Trotterization, wherein the Pauli gadgets have the same sequencing by set as the Pauli strings;
• diagonalise each set of Pauli gadgets to convert the Pauli gadgets into phase gadgets;
• and
• transform the phase gadgets into one- and two-qubit native gates to generate the quantum circuit.

A computer-implemented method of generating a quantum circuit from a Hamiltonian using a parameterised operator including excitation operators to represent an excitation of a reference state, wherein multi-qubit Pauli operators, referred to as Pauli strings, are determined from each excitation operator, the method comprising:

• partitioning the Pauli strings into mutually commuting sets and sequencing the Pauli strings by set;
• generating Pauli gadgets from the Pauli strings by Trotterization, wherein the Pauli gadgets have the same sequencing by set as the Pauli strings;
• diagonalising each set of Pauli gadgets to convert the Pauli gadgets into phase gadgets;
• and
• transforming the phase gadgets into one- and two-qubit native gates to generate the quantum circuit.

A system comprising at least one processor and a compiler configured to run on the processor to generate a quantum circuit from a Hamiltonian using a parameterised operator including excitation operators to represent an excitation of a reference state, wherein multi-qubit Pauli operators, referred to as Pauli strings, are determined from each excitation operator, the compiler being configured to:

• partition the Pauli strings into mutually commuting sets and sequencing the Pauli strings by set;
• generate Pauli gadgets from the Pauli strings by Trotterization, wherein the Pauli gadgets have the same sequencing by set as the Pauli strings;
• diagonalise each set of Pauli gadgets to convert the Pauli gadgets into phase gadgets;
• and
• transform the phase gadgets into one- and two-qubit native gates to generate the quantum circuit.