Simulating large-size quantum spin chains on cloud quantum computers

Quantum computers have the potential to efficiently simulate other quantum systems, especially when their size is large and classical simulation is not feasible. Despite the total qubit number reaching beyond one hundred in several existing quantum devices, their applicability is still plagued by the prevalent noise and errors. Here we present an analysis of a physics-motivated variational ansatz for the XXZ spin chain and report realizations on various IBM quantum computers to simulate ground states of quantum spin chains with qubit numbers ranging from 4 to 102. The estimated ground-state energies from these experiments across different backends and with varying sizes of system reach the expected values within a few error percentages. The enabling factors for accurate large realizations include the use of short-depth physics-motivated ansatzes and efficient and scalable energy measurement and error mitigation, particularly using a reference state in the zero-noise extrapolation.

Ref: Phys. Rev. Research 5, 013183 (2023)Phys. Rev. Research 5, 013183 (2023)