Many-body localization, long range interactions and EPR pairs

主讲人 (Speaker): 王佳 博士

主讲人单位 (Speaker's Institute): Swinburne Univ, Australia

邀请人 (Invited by): 俞振华

时间 (Time): 星期四, 2017/03/30 - 11:00 to 12:00

地点 (Location): 珠海校区行政楼八层天琴引力中心大会议室

摘要 (Abstract):

Under the effect of disorder, isolated interacting quantum systems can have extraordinary properties: localization (failure to reach thermal equilibrium), preserving quantum information and protection of (symmetry breaking and/or topological) quantum order in highly excited states. This remarkable quantum effect, namely many-body localization, has attracted tremendous interest recently, and is believed to exist in non-interacting system and persist with short-range interaction. We theoretically study the localization phenomenon under the effect of long-range interactions. We also explore the possibility of using localization phase to preserve quantum information, with the focus on an important quantum information source: the Einstein–Podolsky–Rosen (EPR) pair. EPR pair of qubits plays a critical role in many quantum protocol applications such as quantum communications and quantum teleportation. Due to interaction with the environment, an EPR pair might lose its entanglement and can no longer serve as useful quantum resources. On the other hand, it has been suggested that introducing disorder into environment might help to prevent thermalization and improve the preservation of entanglement. We theoretically investigate the time evolution of quantum entanglement of an EPR pair in a random-field XXZ spin chain model in the Anderson localized (AL) and many-body localized (MBL) phases. We find that the entanglement between the qubits decreases and approaches to a plateau in the AL phase, but shows a power-law decrease after some critical time determined by the interaction strength in the MBL phase. Our findings, on one hand, can be used as a practical indicator to distinguish the AL and MBL phase; on the other hand, shed lights on applying AL/MBL to improve quantum information storage.

主讲人简介 (Speaker's CV):

Dr. Jia Wang obtained his Ph.D in physics from Univ of Colorado at Boulder in 2012. He is currently a research associate at Swinburne University of Technology in Australia.