非エルミート量子系における例外点の遷移を観測(Scientists Observe Transition Between Two Types of Exceptional Points in Non-Hermitian Quantum Systems)

2026-03-18 中国科学院(CAS)

中国科学院・精密測量科学技術創新研究院(APM)などの研究チームは、非エルミート量子系における2種類の例外点(EP)間の遷移を初めて実験的に観測した。独自開発のイオントラップチップを用い、散逸とデコヒーレンスの両効果を取り入れた「リンドブラッド例外点」を提案。従来は散逸のみが考慮されていたが、本研究では両者の相互作用により、2次・3次の性質を併せ持つハイブリッド例外点が生成・移動・消失する挙動を解明した。さらに量子ジャンプに由来する高次例外点の移動も確認され、開放量子系における基礎物理の理解を深化させるとともに、精密計測や量子制御への応用可能性を示した。

<関連情報>

量子ジャンプによって誘発される高次リウヴィル特異点の実験的証拠 Experimental witness of quantum jump induced high-order Liouvillian exceptional points

Zhuo-Zhu Wu,Pei-Dong Li,Tai-Hao Cui,Jia-Wei Wang,Yuan-Zhang Dong,Shuang-Qing Dai,Ji Li,Ya-Qi Wei,Quan Yuan,Xiao-Ming Cai,Liang Chen,Jian-Qi Zhang,Hui Jing & Mang Feng
Nature Communications  Published:22 January 2026
DOI:https://doi.org/10.1038/s41467-026-68705-9

非エルミート量子系における例外点の遷移を観測(Scientists Observe Transition Between Two Types of Exceptional Points in Non-Hermitian Quantum Systems)

Abstract

The exceptional point has presented considerably interesting and counterintuitive phenomena associated with nonreciprocity, precision measurement, and topological dynamics. The Liouvillian exceptional point (LEP), involving the interplay of energy loss and decoherence inherently relevant to quantum jumps, has recently drawn much attention due to capability to fully capture quantum system dynamics and naturally facilitate non-Hermitian quantum investigations. It was also predicted that quantum jumps could give rise to third-order LEPs in two-level quantum systems for its high dimensional Liouvillian superoperator, which, however, has never been experimentally confirmed until now. Here we report the observation of the third-order LEPs emerging from quantum jumps in an ultracold two-level trapped-ion system. Moreover, by combining decay with dephasing processes, we present the experimental exploration of LEPs involving combinatorial effect of decay and dephasing. In particular, due to non-commutativity between the Lindblad superoperators governing LEPs for decay and dephasing, we witness the movement of LEPs driven by the competition between decay and dephasing occurring in an open quantum system. This unique feature of non-Hermitian quantum systems paves a new avenue for modifying nonreciprocity, enhancing precision measurement, and manipulating topological dynamics by tuning the LEPs.

1701物理及び化学
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