collaborators

5 papers

cond-mat.stat-mech2026

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

Kohei Fukai, Balázs Pozsgay, István Vona

Free-fermion solvability in quantum spin systems is increasingly understood to be governed by a graph Clifford algebra defined from the frustration graph of the Hamiltonian. When t…

cond-mat.stat-mech2026

Dissipative free fermions in disguise

Kohei Fukai, Hironobu Yoshida, Hosho Katsura

Recently, a class of spin chains known as ``free fermions in disguise'' (FFD) has been discovered, which possess hidden free-fermion spectra even though they are not solvable via t…

cond-mat.stat-mech2026

Solving models with generalized free fermions I: Algebras and eigenstates

Kohei Fukai, Balázs Pozsgay, István Vona

We study quantum spin chains solvable via hidden free fermionic structures. We study the algebras behind such models, establishing connections to the mathematical literature of the…

cond-mat.stat-mech2025

Integrability of a family of clean SYK models from the critical Ising chain

Kohei Fukai, Hosho Katsura

We establish the integrability of a family of Sachdev-Ye-Kitaev (SYK) models with uniform -body interactions. We derive the R-matrix and mutually commuting transfer matrices tha…

cond-mat.stat-mech2025

A free fermions in disguise model with claws

Kohei Fukai, István Vona, Balázs Pozsgay

Recently, several spin chain models have been discovered that admit solutions in terms of "free fermions in disguise." A graph-theoretical treatment of such models was also establi…