量子信息交叉中心学术报告024

Title: Polariton Qubit ?----Split-ring polariton condensate as a macroscopic two-level quantum system

Speaker: Prof. Yan Xue, Department of Physics, Jilin University(薛艳副教授，吉林大学物理学院)

Place: RM 101，Bulg. 2，Xixi Campus (西溪校区西二楼101室)

Date and time: 10：00，Aug 6^th，2019 （8月6日周二上午10：00）

Abstract：Superposition states of circular currents of exciton-polaritons mimic the superconducting flux qubits. The current states are formed by a macroscopic number of bosonic quasiparticles that compose a single quantum state of a many-body condensate. The essential difference between a polariton fluid and a supercurrent comes from the fact that polaritons are electrically neutral, and the magnetic field would not have a significant effect on a polariton flow. Nevertheless, the phase of a polariton condensate must change by an integer number of 2 , when going around the ring. If one introduces a -phase delay line in the ring, the system is obliged to propagate a clockwise or anticlockwise circular current to reduce the total phase gained over one round-trip to zero or to build it up to 2 . We show that such a -delay line can be provided by a dark soliton embedded into a ring condensate and pinned to a potential well created by the C-shape non-resonant pump-spot. The physics of resulting split-ring polariton condensates is essentially similar to the physics of flux qubits. In particular，they exhibit pronounced coherent oscillations passing periodically through clockwise and anticlockwise current states. We predict that these oscillations should persist far beyond the coherence time of the polariton condensates. As a consequence， the qubits based on split-ring polariton condensates are expected to be characterized by a very high figure of merit that makes them a valuable alternative to superconducting qubits.

薛艳博士简介：薛艳，女，吉林大学物理学院副教授，2007年于吉林大学博士毕业并留校工作。此后分别在韩国仁和大学从事博士后研究、在波兰物理科学院任助理教授，2019年访问西湖大学极化激元国际研究中心。主要从事半导体微腔结构中与非低温固态玻色爱因斯坦凝聚相关的理论工作以及半经典量子光学领域相关理论工作，曾在Phys. Rev. Lett.(封面文章)，Opt. Lett.，Opt. Express，Phys. Rev. A/B等国际物理学学术期刊发表论文20余篇，主持完成国家自然科学基金青年基金和面上基金。