题目：Quantum metrology and Einstein-Podolsky-Rosen experiment with Bose-Einstein condensates on an atom chip (原子芯片上的量子精密测量与EPR纠缠)

报告人：李奕璠 博士后 （巴塞尔大学）

时 间：2023年11月14日（周二）晚19:00

地 点：腾讯会议 会议号：875-814-313

摘要：

Atom interferometers find a broad range of applications in precision measurements of physical quantities. In our experiment, we perform internal-­state interferometry with a pseudo spin-1/2 Bose Einstein condensate (BEC) of Rubidium-87 on an atom chip. The measurement precision is limited by the finite coherence time of the atoms, which restricts the interrogation time. I will present our work that investigates and confirms a new decoherence mechanism in such a two-component BEC, which sets a fundamental limitation to the temporal coherence in the atomic ensembles.

I will also present our recent experiment, which for the first time demonstrates Einstein-Podolsky-Rosen (EPR) paradox with two spatially separated many-particle systems. The EPR paradox was conceived in 1935 to demonstrate the conflict between quantum physics and the local realist description of nature that characterizes classical physics. In our experiment, we first entangle about 1400 atoms in a single condensate by engineering interatomic interactions. Subsequently, we split this entangled many-particle system into two halves and separated them spatially. Our technique allows us to individually address the collective spins of the two BECs, thereby realizing arbitrary spin measurements on the two systems. We observe strong correlations between the split systems, allowing us to demonstrate the paradoxical situation envisioned by EPR. The prepared EPR entanglement not only reveals the non-local character of quantum physics on a mesoscopic level, but also provides key resources in quantum metrology.

简历：

李奕璠，2012-2016年本科就读于清华大学工程物理系，2016年-2021博士就读于清华大学，方向为冷原子实验与量子精密测量。博士毕业后至今于瑞士巴塞尔大学从事博士后研究，研究内容为利用原子芯片上的旋量玻色爱因斯坦凝聚体进行量子纠缠态的制备与探测，及其在量子计量学中的应用。

联系方式：ygyao@bit.edu.cn

邀请人： 姚裕贵 教授

网 址：/

承办单位：物理学院、先进光电量子结构设计与测量教育部重点实验室

*Title：Quantum metrology and Einstein-Podolsky-Rosen experiment with Bose-Einstein condensates on an atom chip

*Reporter：Yifan Li postdoc researcher（University of Basel）

*Time：2023, Nov14, 19:00

*Place：Conference Number: 875-814-313

*Contact Person: Yugui Yao

*Abstract:

Atom interferometers find a broad range of applications in precision measurements of physical quantities. In our experiment, we perform internal-­state interferometry with a pseudo spin-1/2 Bose Einstein condensate (BEC) of Rubidium-87 on an atom chip. The measurement precision is limited by the finite coherence time of the atoms, which restricts the interrogation time. I will present our work that investigates and confirms a new decoherence mechanism in such a two-component BEC, which sets a fundamental limitation to the temporal coherence in the atomic ensembles.

I will also present our recent experiment, which for the first time demonstrates Einstein-Podolsky-Rosen (EPR) paradox with two spatially separated many-particle systems. The EPR paradox was conceived in 1935 to demonstrate the conflict between quantum physics and the local realist description of nature that characterizes classical physics. In our experiment, we first entangle about 1400 atoms in a single condensate by engineering interatomic interactions. Subsequently, we split this entangled many-particle system into two halves and separated them spatially. Our technique allows us to individually address the collective spins of the two BECs, thereby realizing arbitrary spin measurements on the two systems. We observe strong correlations between the split systems, allowing us to demonstrate the paradoxical situation envisioned by EPR. The prepared EPR entanglement not only reveals the non-local character of quantum physics on a mesoscopic level, but also provides key resources in quantum metrology.

*Profile：