Digital-analog quantum computation with arbitrary two-body Hamiltonians
Mikel Garcia de Andoin, Álvaro Sáiz, P. Pérez-Fernández, Lucas Lamata, Izaskun Oregi, Mikel Sanz
Abstract
Digital-analog quantum computing is a computational paradigm which employs an analog Hamiltonian resource together with single-qubit gates to reach universality. Here, we design a new scheme which employs an arbitrary two-body source Hamiltonian, extending the experimental applicability of this computational paradigm to most quantum platforms. We show that the simulation of an arbitrary two-body target Hamiltonian of $n$ qubits requires $\mathcal{O}({n}^{2})$ analog blocks with guaranteed positive times, providing a polynomial advantage compared to the previous scheme. Additionally, we propose a classical strategy which combines a Bayesian optimization with a gradient descent method, improving the performance by $\ensuremath{\sim}55%$ for small systems measured in the Frobenius norm.