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

DOI:10.7498/aps.70.230101

在傳統(tǒng)固體電子材料中,量子多體物理的研究對(duì)象多為處于熱力學(xué)平衡態(tài)(熱力學(xué)性質(zhì))或近平衡態(tài)(輸運(yùn)性質(zhì))的系統(tǒng),而對(duì)遠(yuǎn)離熱力學(xué)平衡態(tài)的性質(zhì)較少涉及.近十年來(lái),由于量子調(diào)控技術(shù)和測(cè)量手段的飛速發(fā)展,在凝聚態(tài)物理、超冷原子、固態(tài)量子信息等領(lǐng)域中涌現(xiàn)出大量新型的人造量子多體系統(tǒng).通過(guò)動(dòng)態(tài)調(diào)控物理參數(shù),或者將系統(tǒng)耦合上非平衡的環(huán)境,人們可以將這類量子多體系統(tǒng)驅(qū)動(dòng)到遠(yuǎn)離平衡態(tài)的狀態(tài).由于其獨(dú)特的性質(zhì),這類新型量子關(guān)聯(lián)體系會(huì)演生出一些與傳統(tǒng)平衡態(tài)多體系統(tǒng)完全不同的新現(xiàn)象與新物理,很多重要的物理概念(如拓?fù)湫?、自發(fā)對(duì)稱破缺、普適類)在非平衡物理的框架下可能被賦予新的內(nèi)涵.同時(shí),由于量子技術(shù)的飛速發(fā)展,理解這類復(fù)雜系統(tǒng)對(duì)于以量子計(jì)算和量子調(diào)控為代表的新一代量子科學(xué)技術(shù)的發(fā)展具有重要的現(xiàn)實(shí)意義.

非平衡量子多體系統(tǒng)是一個(gè)嶄新的研究領(lǐng)域,其中有大量的未解之謎.由于其具有強(qiáng)關(guān)聯(lián)和非平衡的雙重困難,人們對(duì)這一系統(tǒng)的認(rèn)知極其有限.同時(shí),非平衡量子關(guān)聯(lián)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(tài)物理、原子分子物理和量子光學(xué)、量子信息與量子計(jì)算、非平衡統(tǒng)計(jì)物理等諸多現(xiàn)代物理學(xué)的前沿領(lǐng)域.這些不同體系中涌現(xiàn)出來(lái)的非平衡量子關(guān)聯(lián)現(xiàn)象,既融合了各自體系的不同特征,又展現(xiàn)出普適的一般規(guī)律.我們期待未來(lái)不同學(xué)科的物理思想和研究方法在這一領(lǐng)域交叉融合,碰撞出更為絢麗的火花.本專題邀請(qǐng)了若干活躍在這一新興領(lǐng)域的專家撰稿,重點(diǎn)介紹非平衡和開(kāi)放量子多體系統(tǒng)相關(guān)的最新研究進(jìn)展.內(nèi)容涵蓋了非平衡量子磁性與超導(dǎo)、周期驅(qū)動(dòng)的量子動(dòng)力學(xué)、耗散與非厄密系統(tǒng)、可積系統(tǒng)、時(shí)間晶體等方向.我們期待專題中介紹的成果能夠加強(qiáng)國(guó)內(nèi)學(xué)者在這一領(lǐng)域的交流,激發(fā)讀者的興趣,吸引更多青年學(xué)者和學(xué)生加入到這一新興領(lǐng)域的研究中.

(客座編輯:蔡子 上海交通大學(xué))

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