  We describe a compilation strategy for Variational Quantum Eigensolver (VQE)
algorithms which use the Unitary Coupled Cluster (UCC) ansatz, designed to
reduce circuit depth and gate count. This is achieved by partitioning Pauli
exponential terms into mutually commuting sets. These sets are then
diagonalised using Clifford circuits and synthesised using the phase polynomial
formalism. This strategy reduces cx depth by 75.4% on average, and by up to
89.9%, compared to naive synthesis for a variety of molecules, qubit encodings
and basis sets.
