报告摘要：Advances in quantum technologies are pushing towards building complex quantum systems from individual atoms, ions, photons, and solid-state qubits. The engineered quantum many-body systems are often constantly driven by external fields and always in contact with external bath. Together with a great degree of controllability for microscopic interactions, they offer an ideal platform to explore non-equilibrium phases of light and matter in driven and open settings, about which little is known. The biggest challenge in this endeavor however lies at the difficulty of scaling up the system size while maintaining controllability. In this talk, I will introduce an approach that circumvents the issue of scalability based on the notion of finite-component system phase transition[1,2,3], thereby allowing the realization of non-equilibrium phases of matter with controlled quantum systems that are currently available in labs [4,5]. I will show how the simultaneously large spin-boson coupling strength and detuning lead to the thermodynamic limit of infinite boson excitations in which finite-component quantum systems could undergo a superradiant phase transition and how such an exotic limit can be engineered in physical systems such as ion-traps. Finally, the recent experimental realization of the finite-component system phase transition in trapped-ion will be discussed. 
 M.-J. Hwang, R. Puebla, and M. B. Plenio Physical Review Letters 115, 180404 (2015)
 M.-J. Hwang and M. B. Plenio Physical Review Letters 117, 123602 (2016)
 R. Puebla, M.-J. Hwang, J. Casanova, and M. B. Plenio Physical Review Letters 118, 073001 (2017)
 M.-J. Hwang, P. Rabl, and M. B. Plenio, Physical Review A 97, 013825 (2018)
 B.-B. Wei, G. Sun, and M.-J. Hwang Physical Review B 100, 195107 (2019)
 M.-L. Cai, Z.-D. Liu, W.-D. Zhao, Y.-K. Wu , Q.-X. Mei , Y. Jiang , L. He , X. Zhang, Z.-C. Zhou and L.-M. Duan Nature Communication 12, 1126 (2021)
报告人简介：Prof. Myung-Joong Hwang is an Assistant Professor of Physics at Duke Kunshan University. Prior to joining Duke Kunshan University in 2019, he has been a postdoctoral researcher in the group of Prof. Martin Plenio at the Institute of Theoretical Physics at Ulm University, Germany from 2014 to 2019. His research interest lies at the interface of quantum optics, condensed matter physics, and quantum technology and covers strongly interacting light-matter interactions and phase transitions in small-scale controlled quantum systems. He has published 19 papers in refereed Journals, including 6 papers in Physical Review Letters.