Finite-temperature quenches of local edge memory and nonlocal Majorana parity in the Kitaev chain
Phys. Rev. A 114, 043717 – Published 13 October, 2026
DOI: https://doi.org/10.1103/8zkj-2k3d
Abstract
We compare local and nonlocal correlations after two finite-temperature quenches of the quadratic Kitaev chain. Exact Gaussian dynamics from a real Majorana covariance matrix is checked against an independent Bogoliubov-pseudospin solution. A sudden pairing quench in a periodic ring produces a nonthermal stationary pairing amplitude that decreases inversely with the initial temperature at high temperature. With the nearest-neighbor hopping amplitude denoted by and temperatures expressed in energy units, an initial temperature of gives an energy-matched Gibbs temperature of approximately . The stationary pairing magnitude is smaller than this Gibbs prediction, and the mode occupations cannot be described by a single temperature. In an open chain quenched into the topological regime, boundaries emit dispersive dimer fronts, and the finite-size infinite-time average retains a local edge-density deficit. In contrast, projection onto the final separated Majorana modes gives parity consistent with zero within double-precision numerical accuracy for the studied sudden quench and cosine ramp of duration , where is the reduced Planck constant. For exponentially clustered, parity-even grand-canonical initial states, locality also prevents parity that remains finite as the chain grows from being generated by uniformly bounded local quadratic Hamiltonian controls of system-size-independent duration. This argument does not exclude parity-selective initialization, measurement and postselection, feedback, dissipation, nonlocal couplings, or durations that grow with system size.