Khamoshi, ArminChen, Guo P.Evangelista, Francesco A.Scuseria, Gustavo E.2022-12-162022-12-162022Khamoshi, Armin, Chen, Guo P., Evangelista, Francesco A., et al.. "AGP-based unitary coupled cluster theory for quantum computers." <i>Quantum Science and Technology,</i> 8, no. 1 (2022) IOP Publishing: https://doi.org/10.1088/2058-9565/ac93ae.https://hdl.handle.net/1911/114150Electronic structure methods typically benefit from symmetry breaking and restoration, specially in the strong correlation regime. The same goes for ansätze on a quantum computer. We develop a unitary coupled cluster method based on the antisymmetrized geminal power (AGP)—a state formally equivalent to the number-projected Bardeen–Cooper–Schrieffer wavefunction. We demonstrate our method for the single-band Fermi–Hubbard Hamiltonian in one and two dimensions. We also explore post-selection as a state preparation step to obtain correlated AGP and prove that it scales no worse than O(√M) in the number of measurements, thereby making it a less expensive alternative to gauge integration to restore particle number symmetry.engThis is an author's post-print. The published article is copyrighted by IOP PublishingJournal articlehttps://doi.org/10.1088/2058-9565/ac93ae