Quantum circuit cutting minimising loss of qubit entanglement

Quantum circuit cutting allows an arbitrary circuit to be executed on a quantum computer with fewer qubits by fragmenting it into subcircuits, each with fewer qubits. If such a method is to be employed, it is critical that the quantum properties of the original circuit, such as entanglement, are not violated. This paper demonstrates, using circuit cutting tools, how to select circuit bipartitions while prioritising the preservation of underlying entanglement between the qubits. We present two entanglement-based criteria. The former minimises losses of reduced-state pairwise qubit entanglement, and has polynomial complexity in the number of qubits. The latter minimises loss of multipartite entanglement across qubit bipartitions, with exponential complexity. Violations of entanglement with frequencies up to 72% are observed in current circuit cutting software. This paper describes how to prevent such violations, or to minimise qubit entanglement losses, fragmenting circuits with pairwise qubit negativity losses of only 5%, and for certain circuits 0% von Neumann entropy losses across qubit bipartitions.