Classical simulation of the quantum-annealer reservoir map

Determine whether, and at what accuracy and computational cost, state-of-the-art classical dynamical simulations can reproduce the experimentally accessible reservoir map generated by finite-time, out-of-equilibrium reverse-annealing dynamics on the 4,500-qubit quantum annealer, and establish whether reproducing this map is classically intractable.

Background

The reservoir map is generated by reverse-annealing dynamics in a large, nonplanar, high-degree transverse-field Ising system. Although the Hamiltonian is stoquastic and its equilibrium and ground-state properties can be approached with sign-problem-free classical Monte Carlo methods, the authors emphasize that these static properties do not determine the computational difficulty of the finite-time, out-of-equilibrium dynamics used for temporal information processing.

The paper reports that spin-vector Monte Carlo simulations do not reproduce the experimentally observed memory performance, but this discrepancy does not establish a general classical computational advantage or prove classical intractability. The unresolved problem is therefore to quantify the classical resources required to reproduce the experimentally accessible reservoir transformation, including the relevant accuracy and computational cost, and to determine whether such reproduction is computationally infeasible.