Southwest Quantum Information and Technology

Variational quantum simulation of valence-bond solids

Presenting Author: Daniel Huerga, University of British Columbia

We present a hybrid algorithm to simulate two-dimensional frustrated quantum magnets in the thermodynamic limit. Built upon a cluster-Gutzwiller ansatz, a shallow U(1) symmetric parameterized quantum circuit provides the wave function of the cluster, while information of the infinite lattice is provided through a self-consistent mean-field embedding. We benchmark the algorithm on the J1-J2 Heisenberg anti-ferromagnet on the square lattice and uncover its phase diagram, which hosts long-range ordered phases, as well as an intermediate valence-bond solid (VBS) phase characterized by a periodic pattern of strongly-correlated 2x2 plaquettes. Our results show that the mean-fields guide its convergence avoiding the so-called barren-plateaux, large flat regions in the optimization landscape that generically impede scalability of variational quantum algorithms. The plaquette-VBS phase is accessed by smoothly driving the system from the Neel phase through a quantum phase transition, opening the route for its quantum simulation with current superconducting circuit technology.

Read this article online: https://arxiv.org/abs/2201.02545

(Session 5 : Thursday from 5:00 pm - 7:00 pm)