Hamiltonian tomography for quantum many-body systems with arbitrary couplings

TL;DR

This paper introduces a scalable tomographic method for characterizing all coupling terms in complex many-body quantum Hamiltonians using synchronized dynamical decoupling, robust against typical experimental noise.

Contribution

It presents a novel, scalable measurement scheme for Hamiltonian tomography in many-body systems with arbitrary couplings, utilizing synchronized pulses for parameter retrieval.

Findings

Scheme is fully scalable with the number of qubits.

Robust to typical pulse errors and experimental noise.

Simulation shows effective parameter estimation in noisy conditions.

Abstract

Characterization of qubit couplings in many-body quantum systems is essential for benchmarking quantum computation and simulation. We propose a tomographic measurement scheme to determine all the coupling terms in a general many-body Hamiltonian with arbitrary long-range interactions, provided the energy density of the Hamiltonian remains finite. Different from quantum process tomography, our scheme is fully scalable with the number of qubits as the required rounds of measurements increase only linearly with the number of coupling terms in the Hamiltonian. The scheme makes use of synchronized dynamical decoupling pulses to simplify the many-body dynamics so that the unknown parameters in the Hamiltonian can be retrieved one by one. We simulate the performance of the scheme under the influence of various pulse errors and show that it is robust to typical noise and experimental imperfections.