  We draw attention to a variant of the iterative qubit coupled cluster (iQCC)
method that only uses Clifford circuits. The iQCC method relies on a small
parameterized wave function ansatz, which takes form as a product of
exponentiated Pauli word operators, to approximate the ground state electronic
energy of a mean field reference state through iterative qubit Hamiltonian
transformations. In this variant of the iQCC method, the wave function ansatz
at each iteration is restricted to a single exponentiated Pauli word operator
and parameter. The Rotosolve algorithm utilizes Hamiltonian expectation values
computed with Clifford circuits to optimize the single-parameter Pauli word
ansatz. Although the exponential growth of Hamiltonian terms is preserved with
this variation of iQCC, we suggest several methods to mitigate this effect.
This method is useful for near-term variational quantum algorithm applications
as it generates good initial parameters by using Clifford circuits which can be
efficiently simulated on a classical computers according to the Gottesman-Knill
theorem. It may also be useful beyond the NISQ era to create short-depth
Clifford pre-optimized circuits that improve the success probability for
fault-tolerant algorithms such as phase estimation.
