Spin-incoherent Mott-Thouless pumps
arXiv:2607.27321
The paper introduces Mott‑Thouless pumps that achieve quantized charge transport in spin‑incoherent, high‑entropy Mott states, demonstrating analytical protection of the pumped charge and supporting it with exact real‑time simulations.
Abstract
A Thouless pump describes a system in which a quantized amount of charge is transported by one lattice spacing per cycle when the parameters of a Hamiltonian are varied slowly and periodically. In the standard case, this quantization requires the system to remain in its ground state with vanishing thermodynamic entropy throughout the pumping process. Here, we introduce a class of Mott-Thouless pumps, which operate in highly entropic, spin-incoherent Mott states. We show analytically that these states exhibit exponentially protected quantized transport despite their extensive entropy, because the pumped charge resides in a gapped sector that remains dynamically decoupled from the hot spin degrees of freedom. By contrast, motivated by a recent experimental realization, we identify other classes of Mott-Thouless pumps that lack this protection. In these systems, spin excitations can efficiently generate charge excitations, leading to a rapid breakdown of quantized transport. Our analytical results are supported by numerically exact real-time simulations of finite systems.
18 + 11 pages; 6 + 7 figures