Universal measurement-based quantum computation with spin-2 Affleck-Kennedy-Lieb-Tasaki states

TL;DR

This paper proves that the spin-2 AKLT state on a square lattice is a universal resource for measurement-based quantum computation by converting it into random graph states and analyzing their percolation properties.

Contribution

It introduces a method to certify the universality of the spin-2 AKLT state for quantum computation via local measurements and percolation analysis, including an exact weight formula for measurement outcomes.

Findings

Spin-2 AKLT state on square lattice is a universal resource.

High-probability percolation in the resulting random graph states.

Potential for fault-tolerant quantum computation with 3D AKLT states.

Abstract

We demonstrate that the spin-2 Affleck-Kennedy-Lieb-Tasaki (AKLT) state on the square lattice is a universal resource for the measurement-based quantum computation. Our proof is done by locally converting the AKLT to two-dimensional random planar graph states and by certifying that with high probability the resulting random graphs are in the supercritical phase of percolation using Monte Carlo simulations. One key enabling point is the exact weight formula that we derive for arbitrary measurement outcomes according to a spin-2 POVM on all spins. We also argue that the spin-2 AKLT state on the three-dimensional diamond lattice is a universal resource, the advantage of which would be the possibility of implementing fault-tolerant quantum computation with topological protection. In addition, as we deform the AKLT Hamiltonian, there is a finite region that the ground state can still support a universal resource before making a transition in its quantum computational power.