T-Fermion: A non-Clifford gate cost assessment library of quantum phase estimation algorithms for quantum chemistry

Quantum Phase Estimation is one of the most useful quantum computing algorithms for quantum chemistry and as such, significant effort has been devoted to designing efficient implementations. In this article, we introduce T-Fermion, a library designed to estimate the T-gate cost of such algorithms, for an arbitrary molecule. As examples of usage, we estimate the T-gate cost of a number of simple molecules and compare the same Taylorization algorithms using Gaussian and plane-wave basis. We find out that naïve Taylorization techniques can be surprisingly efficient when used in plane waves and combined with QROM techniques.