Tunneling-induced restoration of classical degeneracy in quantum kagome ice
Journal
Physics Review
Journal Volume
99
Journal Issue
13
Date Issued
2018-06-21
Author(s)
Abstract
Quantum effect is expected to dictate the behaviour of physical systems at
low temperature. For quantum magnets with geometrical frustration, quantum
fluctuation usually lifts the macroscopic classical degeneracy, and exotic
quantum states emerge. However, how different types of quantum processes
entangle wave functions in a constrained Hilbert space is not well understood.
Here, we study the topological entanglement entropy (TEE) and the thermal
entropy of a quantum ice model on a geometrically frustrated kagome lattice. We
find that the system does not show a $Z_2$ topological order down to extremely
low temperature, yet continues to behave like a classical kagome ice with
finite residual entropy. Our theoretical analysis indicates an intricate
competition of off-diagonal and diagonal quantum processes leading to the
quasi-degeneracy of states and effectively, the classical degeneracy is
restored.
Subjects
Physics - Strongly Correlated Electrons; Physics - Strongly Correlated Electrons
Publisher
AMER PHYSICAL SOC
Description
14 pages, 16 figures, added ED results for the effective model