Practical Quantum State Tomography for Gibbs states [article]

Yotam Y. Lifshitz, Eyal Bairey, Eli Arbel, Gadi Aleksandrowicz, Haggai Landa, Itai Arad
2021 arXiv   pre-print
Quantum state tomography is an essential tool for the characterization and verification of quantum states. However, as it cannot be directly applied to systems with more than a few qubits, efficient tomography of larger states on mid-sized quantum devices remains an important challenge in quantum computing. We develop a tomography approach that requires moderate computational and quantum resources for the tomography of states that can be approximated by Gibbs states of local Hamiltonians. The
more » ... oposed method, Hamiltonian Learning Tomography, uses a Hamiltonian learning algorithm to get a parametrized ansatz for the Gibbs Hamiltonian, and optimizes it with respect to the results of local measurements. We demonstrate the utility of this method with a high fidelity reconstruction of the density matrix of 4 to 10 qubits in a Gibbs state of the transverse-field Ising model, in numerical simulations as well as in experiments on IBM Quantum superconducting devices accessed via the cloud.
arXiv:2112.10418v1 fatcat:zwsslz5psfbubmjcb2bqohkjru