NSF Nanoscale Science and Engineering Center, University of California, Berkeley, California 94720, USA.
Phys Rev Lett. 2023 Jan 20;130(3):036902. doi: 10.1103/PhysRevLett.130.036902.
The newly discovered valley degree of freedom in atomically thin two-dimensional transition metal dichalcogenides offers a promising platform to explore rich nonlinear physics, such as spinor Bose-Einstein condensate and novel valleytronics applications. However, the critical nonlinear effect, such as valley polariton bosonic stimulation, has long remained an unresolved challenge due to the generation of limited polariton ground state densities necessary to induce the stimulated scattering of polaritons in specific valleys. Here, we report the self-induced valley bosonic stimulation of exciton polaritons via spin-valley locking in a WS_{2} monolayer microcavity. This is achieved by the resonant injection of valley polaritons at specific energy and wave vector, which allows spin-polarized polaritons to efficiently populate their ground state and induce a valley-dependent bosonic stimulation. As a result, we observe the nonlinear self-amplification of polariton emission from the valley-dependent ground state. Our finding paves the way for the investigation of spin ordering and phase transitions in transition metal dichalcogenides polariton Bose-Einstein condensate, offering a promising route for the realization of polariton spin lattices in moiré polariton systems and spin lasers.
新发现的原子薄二维过渡金属二硫属化物中的谷自由度为探索丰富的非线性物理提供了一个很有前景的平台，例如旋量玻色-爱因斯坦凝聚和新颖的谷电子学应用。然而，由于产生有限的极化激元基态密度以在特定谷中诱导极化激元的受激散射，关键的非线性效应，如谷极化激元玻色子激发，长期以来一直是一个未解决的挑战。在这里，我们通过在 WS_{2}单层微腔中自旋-谷锁定来报告激子极化激元的自诱导谷玻色子激发。这是通过在特定能量和波矢处共振注入谷极化激元来实现的，这允许自旋极化极化激元有效地填充其基态并诱导谷相关的玻色子激发。结果，我们观察到了来自谷相关基态的极化子发射的非线性自放大。我们的发现为研究过渡金属二硫属化物极化子玻色-爱因斯坦凝聚中的自旋有序和相变铺平了道路，为在莫尔极化子系统中实现极化子自旋晶格和自旋激光器提供了一条很有前途的途径。
