Gabbrielli Marco, Smerzi Augusto, Pezzè Luca
QSTAR, INO-CNR and LENS, Largo Enrico Fermi 2, I-50125, Firenze, Italy.
Sci Rep. 2018 Oct 23;8(1):15663. doi: 10.1038/s41598-018-31761-3.
The interplay of quantum and thermal fluctuations in the vicinity of a quantum critical point characterizes the physics of strongly correlated systems. Here we investigate this interplay from a quantum information perspective presenting the universal phase diagram of the quantum Fisher information at a quantum phase transition. Different regions in the diagram are identified by characteristic scaling laws of the quantum Fisher information with respect to temperature. This feature has immediate consequences on the thermal robustness of quantum coherence and multipartite entanglement. We support the theoretical predictions with the analysis of paradigmatic spin systems showing symmetry-breaking quantum phase transitions and free-fermion models characterized by topological phases. In particular we show that topological systems are characterized by the survival of large multipartite entanglement, reaching the Heisenberg limit at finite temperature.
量子临界点附近量子涨落与热涨落的相互作用表征了强关联系统的物理特性。在此，我们从量子信息的角度研究这种相互作用，给出量子相变处量子费舍尔信息的通用相图。相图中的不同区域由量子费舍尔信息相对于温度的特征标度律来确定。这一特性对量子相干性和多体纠缠的热鲁棒性有着直接影响。我们通过对显示对称性破缺量子相变的典型自旋系统以及以拓扑相为特征的自由费米子模型的分析，来支持理论预测。特别是我们表明，拓扑系统的特征是存在大量多体纠缠，在有限温度下达到海森堡极限。
