非平衡量子多體系統專題編者按

Preface to the special topic:Non-equilibrium quantum many-body systems

DOI:10.7498/aps.70.230101

在傳統固體電子材料中,量子多體物理的研究對象多為處于熱力學平衡態(熱力學性質)或近平衡態(輸運性質)的系統,而對遠離熱力學平衡態的性質較少涉及.近十年來,由于量子調控技術和測量手段的飛速發展,在凝聚態物理、超冷原子、固態量子信息等領域中涌現出大量新型的人造量子多體系統.通過動態調控物理參數,或者將系統耦合上非平衡的環境,人們可以將這類量子多體系統驅動到遠離平衡態的狀態.由于其獨特的性質,這類新型量子關聯體系會演生出一些與傳統平衡態多體系統完全不同的新現象與新物理,很多重要的物理概念(如拓撲序、自發對稱破缺、普適類)在非平衡物理的框架下可能被賦予新的內涵.同時,由于量子技術的飛速發展,理解這類復雜系統對于以量子計算和量子調控為代表的新一代量子科學技術的發展具有重要的現實意義.

非平衡量子多體系統是一個嶄新的研究領域,其中有大量的未解之謎.由于其具有強關聯和非平衡的雙重困難,人們對這一系統的認知極其有限.同時,非平衡量子關聯體系的研究范圍不局限于某一特定的物理分支,而是涉及凝聚態物理、原子分子物理和量子光學、量子信息與量子計算、非平衡統計物理等諸多現代物理學的前沿領域.這些不同體系中涌現出來的非平衡量子關聯現象,既融合了各自體系的不同特征,又展現出普適的一般規律.我們期待未來不同學科的物理思想和研究方法在這一領域交叉融合,碰撞出更為絢麗的火花.本專題邀請了若干活躍在這一新興領域的專家撰稿,重點介紹非平衡和開放量子多體系統相關的最新研究進展.內容涵蓋了非平衡量子磁性與超導、周期驅動的量子動力學、耗散與非厄密系統、可積系統、時間晶體等方向.我們期待專題中介紹的成果能夠加強國內學者在這一領域的交流,激發讀者的興趣,吸引更多青年學者和學生加入到這一新興領域的研究中.

(客座編輯:蔡子 上海交通大學)

In the context of traditional solid physics,the majority of studies in quantum many-body physics focus on the systems in or close to the thermodynamic equilibrium state,while the farfrom-equilibrium system is less known in general.In the past decades,due to the rapid development of quantum manipulation and measurement,enormous novel synthetic quantum materials have emerged in condensed matter,ultracold atomic,and solid state quantum information systems,where the systems can be driven out of equilibrium by dynamically tuning the Hamiltonian parameters,or coupling the system to a non-equilibrium bath.Due to its unique feature,such non-equilibrium quantum many-body systems exhibit novel properties that are completely different from the traditional equilibrium quantum many-body systems.Lots of fundamental concepts (for instance,the topological order,spontaneous symmetry breaking and universality class) have to be reexamined in the framework of non-equilibrium physics.Furthermore,understanding such complex quantum systems is also of important practical significance for the development of the new generation of quantum technologies.

As a new branch of physics,non-equilibrium quantum many-body systems are far from being understood due to the intrinsic difficulties of it strongly correlated and non-equilibrium features.At the same time,instead of focusing on a specific branch of physics,the researches in this field involve interdisciplinary theories and methods in condensed matter physics,atomic and molecular physics and quantum optics,quantum information and quantum computation,nonequilibrium statistic physics.The emergent non-equilibrium quantum many-body phenomena in above systems do not only possess the interest of its own,but also exhibit universal behavior that is independent of the details of these systems.It is expected that the interplay between the ideas and methods in various branches of modern physics can trigger exciting physics in this new field.This special topic contains several review papers written by experts working actively in this emergent field.These papers review latest progresses in several important directions in this field,including the non-equilibrium quantum magnetism and superconductivity,periodically driven quantum systems,dissipative and non-Hermitian systems,integrable systems and time crystals.We hope this special topic can inspire the interest of the readers,and attract more young scholars and students to join this exciting field.

Cai Zi

Shanghai Jiao Tong University,China