Preparing the AKLT state on a quantum computer

The preparation and validation of physically interesting and useful quantum states and phases remains an important problem, particularly on modern NISQ devices. A prototypical example is the AKLT model, describing a one-dimensional spin-1 chain with generalized nearest-neighbor, Heisenberg-like interactions. It provides an intuitive realization of a novel, symmetry-protected topological phase displaying fractionalized excitations at the edges, a finite energy gap in the bulk, and a hidden antiferromagnetic ordering. In addition to these exotic properties, the AKLT ground state holds particular promise as a resource for measurement-based quantum computing and other quantum information processing tasks.

In this talk, we describe a sequential procedure for preparing the $N$-site AKLT state on a quantum computer with a circuit depth linear in $N$ and unit success probability independent of $N$. We discuss several strategies for validating the AKLT state preparation through inspection of its underlying symmetries and, finally, analyze the performance of our preparation scheme on IBM-Q.