TY  - JOUR
PB  - SciPost Foundation
DO  - 10.21468/SciPostPhys.15.5.206
TI  - Thermal pure matrix product state in two dimensions: Tracking thermal equilibrium from paramagnet down to the Kitaev honeycomb spin liquid state
PY  - 2023/11/24
UR  - https://scipost.org/SciPostPhys.15.5.206
JF  - SciPost Physics
JA  - SciPost Phys.
VL  - 15
IS  - 5
SP  - 206
A1  - Gohlke, Matthias
AU  - Iwaki, Atsushi
AU  - Hotta, Chisa
AB  - We present the first successful application of the matrix product state (MPS) representing a thermal quantum pure state (TPQ) in equilibrium in two spatial dimensions over almost the entire temperature range. We use the Kitaev honeycomb model as a prominent example hosting a quantum spin liquid (QSL) ground state to target the two specific-heat peaks previously solved nearly exactly using the free Majorana fermionic description. Starting from the high-temperature random state, our TPQ-MPS framework on a cylinder precisely reproduces these peaks, showing that the quantum many-body description based on spins can still capture the emergent itinerant Majorana fermions in a ${\mathbb Z}_2$ gauge field. The truncation process efficiently discards the high-energy states, eventually reaching the long-range entangled topological state approaching the exact ground state for a given finite size cluster. An advantage of TPQ-MPS over exact diagonalization or purification-based methods is its lowered numerical cost coming from a reduced effective Hilbert space even at finite temperature.
ER  -

@Article{10.21468/SciPostPhys.15.5.206,
	title={{Thermal pure matrix product state in two dimensions: Tracking thermal equilibrium from paramagnet down to the Kitaev honeycomb spin liquid state}},
	author={Matthias Gohlke and Atsushi Iwaki and Chisa Hotta},
	journal={SciPost Phys.},
	volume={15},
	pages={206},
	year={2023},
	publisher={SciPost},
	doi={10.21468/SciPostPhys.15.5.206},
	url={https://scipost.org/10.21468/SciPostPhys.15.5.206},
}