报告题目：Entanglement Distribution – Towards a Suburban Quantum Network Link

报告人：周忆如  慕尼黑大学

报告时间：2023年5月10日（周三）10:00

报告地点：理六栋302会议室         

邀请人：颜辉

报告内容：

Heralded entanglement between distant quantum memories is one of the building blocks for quantum networks, which will enable secure quantum communication and distributed quantum computing. To this end, we developed a quantum network link employing entanglement shared between two independently trapped Rb-87 atoms located in buildings 400 m apart. The atoms can be entangled over fibre links with a length of up to 33 km, enabled by mitigating attenuation losses in the long fibres via polarization-preserving quantum frequency conversion. Decoherence of the atomic states reduced the observed atom-atom state fidelity for long fibre lengths.  To overcome this, we implemented a state-selective Raman transfer to transfer the qubit encoding into one with significantly lower sensitivity to fluctuating magnetic fields. As a result, we improved the coherence time from 300 us to 7 ms. This robust qubit encoding enabled the distribution of atom-photon entanglement over 101 km telecom fibre with a fidelity ≥70.8%.This lays the ground for the next steps generating heralded entanglement between a single atom at LMU in Munich and a single atom at MPQ in Garching – approximately 14 km line-of-sight apart.

专家简介：

Yiru Zhou is currently a graduate student at Ludwig-Maximilians-Universität München, Germany, under the supervision of Prof. Harald Weinfurter. In 2020, she completed her Master of Science in Atomic and Molecular Physics from South China Normal University under the supervision of Prof. Hui Yan. Prior to that, in 2017, she obtained her Bachelor of Science in Physics Education from South China Normal University. Her current research focuses on long-distance entanglement distribution and quantum networks.