Hidden Conformal Boundary Data in Finite-Temperature Stabilizer Entropy (opens in new tab)

We study the finite-temperature stabilizer R\'enyi entropy of the open critical quantum spin chains. At R\'enyi index one half, this observable probes the distribution of thermal Pauli-string expectation values and can be written as a sum over absolute values of all square minors of a finite-temperature correlation matrix for the transverse-field Ising chain. We show that this exponentially large sum is exactly reducible to a single Pfaffian. Th...