The paper Iterative Qubit Coupled Cluster approach with efficient screening of generators describes a new screening procedure for generators of the QCC ansatz.

How does one get from defining the flip indices $F(\hat{T})$ of a Pauli term $\hat{P}$:

$$F(\hat{P}) = \{j: \hat{f} ∈\hat{P}\}$$

to the partitioning of the second-quantised Hamiltonian as:




groups the terms with the same flip indices?

$$F(\hat{P}_{i})=F(\hat{P}_{j}),\quad ∀(\hat{P}_{i},\hat{P}_{j}) ∈ \hat{S}_{k}$$

And how is it that Pauli words possessing the same flip indices introduce an equivalence relation on the set of Hamiltonian terms?

  • $\begingroup$ the edit improves the answer, but it would be much better if you could make the post somewhat self-consistent, so that a reader doesn't have to read through the paper to get the basic definitions used in the question $\endgroup$
    – glS
    May 29, 2020 at 7:43


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