Probing Mesonic State Evolution in Mixed-Field Ising Models.

Investigations of quantum many-body systems in- and out- of equilibrium are performed by looking at their response with pump-probe spectroscopy. Quantum computers have proved useful in simulating such experiments and measuring linear responses by exciting the system, evolving, and then measuring observables all in one setting. Here, we use this approach to investigate the mixed field Ising model, where the longitudinal field plays the role of a confining potential that prohibits the spread of the excitations, spinons or domain walls, into space. We study the discrete bound states that arise from such a setting and their evolution under different quench dynamics by initially pumping the chain out of equilibrium then probing various non-equal time correlation functions. Finally, we simulate the experiment on quantum hardware and obtain the linear response by using a functional derivative approach.