Long coherence times for edge spins

Understand

We show that in certain one-dimensional spin chains with open boundary conditions, the edge spins retain memory of their initial state for very long times.

• The long coherence times do not require disorder, only an ordered phase.
• In the integrable Ising and XYZ chains, the presence of a strong zero mode means the coherence time is infinite, even at infinite temperature.
• When Ising is perturbed by interactions breaking the integrability, the coherence time remains exponentially long in the perturbing couplings.