Luo Chengxi, Cuiying Honors College, Lanzhou University

This summer was a different summer. With the support of Cuiying Honors College, I am honored to have the chance to go to Nanyang Technological University to conduct my summer research internship. I spent a month there and Ilearneda lot from professors and studentsatNanyang Technological University. Singapore, as a multicultural platform, gives me the chance to make friends with peoplefromall over the world, enhances my English ability, and broaden my horizon. Nanyang Technological University, as one of the topschoolsinthe world,allows meto think differently, do differently, and speak differently. The style ofbuildingsatNanyangTechnologicalUniversity is new, fashionable,and modernized. It attracts me a lot with its creative design andthebeauty of technology and engineering.

The topic of my summer research internship is valley coherence intheTMD-basedexciton-polaritonsystem. The emerging field of valleytronics aims to coherently manipulate an electron and/or hole’s valley pseudospin as an information-bearing degree of freedom. Monolayer transition metal dichalcogenides, due to their strongly boundexcitons, their degenerate valleys, and their seamless interfacing with photons are a promising candidate for room temperature valleytronics. Although the exciton binding energy suggests room temperature valley coherence should be possible, it has been elusive to date. A potential solution involves theformation of half-light, half-matter cavity polaritons based on 2D material excitons. It has recently been discovered that cavity polaritons can inherit the valley DOF. Inthis summer research internship, some membersofthe group and Idemonstratedthe room-temperature valley coherence of valley polaritons by embedding a monolayer of tungsten diselenide in a monolithic dielectric cavity. The extra decay path introduced by the exciton-cavity coupling, which is free from decoherence, is the key to room-temperature valley coherence preservation. These observations pave the way for practical valleytronic devices.