Pith. sign in

REVIEW 13 cited by

A Unified Graph-Theoretic Framework for Free-Fermion Solvability

Not yet reviewed by Pith; the record is open.

This paper has not been read by Pith yet. Machine review is queued; the pith claim, tier, and objections will appear here once it completes.

SPECIMEN: schema-true, not a live event

T0 review · schema-true

One-sentence machine reading of the paper's core claim.

pith:XXXXXXXX · record.json · timestamp

arxiv 2305.15625 v1 pith:KKH4B32N submitted 2023-05-25 quant-ph cond-mat.str-elmath.CO

A Unified Graph-Theoretic Framework for Free-Fermion Solvability

classification quant-ph cond-mat.str-elmath.CO
keywords solutionfrustrationgraphclaw-freefree-fermionmodelcapturescase
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
0 comments
read the original abstract

We show that a quantum spin system has an exact description by non-interacting fermions if its frustration graph is claw-free and contains a simplicial clique. The frustration graph of a spin model captures the pairwise anticommutation relations between Pauli terms of its Hamiltonian in a given basis. This result captures a vast family of known free-fermion solutions. In previous work, it was shown that a free-fermion solution exists if the frustration graph is either a line graph, or (even-hole, claw)-free. The former case generalizes the celebrated Jordan-Wigner transformation and includes the exact solution to the Kitaev honeycomb model. The latter case generalizes a non-local solution to the four-fermion model given by Fendley. Our characterization unifies these two approaches, extending generalized Jordan-Wigner solutions to the non-local setting and generalizing the four-fermion solution to models of arbitrary spatial dimension. Our key technical insight is the identification of a class of cycle symmetries for all models with claw-free frustration graphs. We prove that these symmetries commute, and this allows us to apply Fendley's solution method to each symmetric subspace independently. Finally, we give a physical description of the fermion modes in terms of operators generated by repeated commutation with the Hamiltonian. This connects our framework to the developing body of work on operator Krylov subspaces. Our results deepen the connection between many-body physics and the mathematical theory of claw-free graphs.

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Forward citations

Cited by 13 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. A Machine-Verified Proof of a Quantum-Optimization Conjecture

    quant-ph 2026-06 accept novelty 8.0 full

    A Lean 4 machine-verified proof establishes that depth-p QAOA on the ring of disagrees attains approximation ratio (2p+1)/(2p+2) exactly.

  2. Enabling Lie-Algebraic Classical Simulation beyond Free Fermions

    quant-ph 2026-04 unverdicted novelty 8.0

    New Pauli orbit and modified Gell-Mann bases enable polynomial-cost Lie-algebraic simulation for permutation-equivariant and bounded-excitation quantum dynamics.

  3. On $R$-parastatistics I: Foundation

    quant-ph 2026-07 conditional novelty 7.0

    R-paraparticles, a class of statistics beyond fermions and bosons, are given a complete local-observable theory — pair creation, defect probes of hidden indices, and Hopf-algebra hidden symmetries — plus a classificat...

  4. Correlation and entanglement dynamics of free fermions in disguise

    cond-mat.stat-mech 2026-07 conditional novelty 7.0

    For Fendley's free-fermions-in-disguise chain, post-quench GGE occupations and local energy-density expectations are derived analytically and match TEBD numerics; the quasi-particle entanglement-growth formula is only...

  5. Enabling Lie-Algebraic Classical Simulation beyond Free Fermions

    quant-ph 2026-04 accept novelty 7.0

    Symmetry-adapted Pauli-orbit and modified Gell-Mann bases make polynomial-dimensional dynamical Lie algebras practically simulable beyond free fermions.

  6. Solving models with generalized free fermions I: Algebras and eigenstates

    cond-mat.stat-mech 2026-02 conditional novelty 7.0

    Spin chains with hidden free-fermion structure acquire explicit exact eigenstates through an anti-symmetric combination of two commuting Hamiltonian copies, demonstrated for the free-fermions-in-disguise model.

  7. Integrability of Goldilocks quantum cellular automata

    quant-ph 2024-04 unverdicted novelty 7.0

    A subclass of Goldilocks QCA including the experimentally implemented one are integrable by mapping to free fermions, with local conserved quantities computed for hardware testing.

  8. Efficiently Simulable Pauli Correlation Encoding

    quant-ph 2026-07 conditional novelty 6.0

    Free-fermion and IQP instantiations of Pauli Correlation Encoding run entirely classically and still give high-quality solutions on MaxCut, MIS, knapsack, and Max3SAT benchmarks.

  9. Correlation and entanglement dynamics of free fermions in disguise

    cond-mat.stat-mech 2026-07 conditional novelty 6.0

    Analytic method for GGE quasi-momentum distribution in degenerate free-fermion models plus a conjecture adjusting the quasi-particle entanglement formula, tested numerically with good agreement on local observables bu...

  10. Free fermions in disguise without exponential degeneracies

    cond-mat.stat-mech 2026-06 unverdicted novelty 6.0

    A perturbation of two Ising chains (or interpolation between Jordan-Wigner and Fendley FFD models) yields an FFD-solvable spin chain without exponential degeneracies for generic couplings.

  11. Solving models with generalized free fermions II: Path-product expansion and conserved charges

    cond-mat.stat-mech 2026-05 unverdicted novelty 6.0

    Derives path-product expansion for free-fermion modes and local conserved charges in generalized free-fermion models from Krylov basis generating function.

  12. On the Complexity of the Succinct State Local Hamiltonian Problem

    quant-ph 2025-09 unverdicted novelty 6.0

    The succinct state 2-local Hamiltonian problem for qubit Hamiltonians is promise-MA-complete.

  13. Frustration graph formalism for qudit observables

    quant-ph 2025-03 unverdicted novelty 6.0

    A frustration graph formalism for prime-d qudit observables yields a unitary map to generalized Pauli form plus bounds on observable sums used for qudit entanglement quantification.