paper

Complexity of frustration: a new source of non-local non-stabilizerness

arXiv:2209.10541 · doi:10.21468/SciPostPhys.15.4.131

Abstract

We advance the characterization of complexity in quantum many-body systems by examining -states embedded in a spin chain. Such states show an amount of non-stabilizerness or "magic" (measured as the Stabilizer Rényi Entropy -SRE-) that grows logarithmic with the number of qubits/spins. We focus on systems whose Hamiltonian admits a classical point with an extensive degeneracy. Near these points, a Clifford circuit can convert the ground state into a -state, while in the rest of the phase to which the classic point belongs, it is dressed with local quantum correlations. Topological frustrated quantum spin-chains host phases with the desired phenomenology, and we show that their ground state's SRE is the sum of that of the -states plus an extensive local contribution. Our work reveals that -states/frustrated ground states display a non-local degree of complexity that can be harvested as a quantum resource and has no counterpart in GHZ states/non-frustrated systems.

8 pages, 3 figures

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