Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom;
Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 0WA, United Kingdom;
Proc Natl Acad Sci U S A. 2014 Jun 17;111(24):8770-5. doi: 10.1073/pnas.1401988111. Epub 2014 Jun 2.
Polariton condensates are macroscopic quantum states formed by half-matter half-light quasiparticles, thus connecting the phenomena of atomic Bose-Einstein condensation, superfluidity, and photon lasing. Here we report the spontaneous formation of such condensates in programmable potential landscapes generated by two concentric circles of light. The imposed geometry supports the emergence of annular states that extend up to 100 μm, yet are fully coherent and exhibit a spatial structure that remains stable for minutes at a time. These states exhibit a petal-like intensity distribution arising due to the interaction of two superfluids counterpropagating in the circular waveguide defined by the optical potential. In stark contrast to annular modes in conventional lasing systems, the resulting standing wave patterns exhibit only minimal overlap with the pump laser itself. We theoretically describe the system using a complex Ginzburg-Landau equation, which indicates why the condensate wants to rotate. Experimentally, we demonstrate the ability to precisely control the structure of the petal condensates both by carefully modifying the excitation geometry as well as perturbing the system on ultrafast timescales to reveal unexpected superfluid dynamics.
极化激元凝聚态是由半物质半光准粒子形成的宏观量子态，因此将原子玻色-爱因斯坦凝聚、超流和光子激光等现象联系起来。在这里，我们报告了在由两个同心光圆产生的可编程势场中自发形成这种凝聚态的情况。所施加的几何形状支持环形态的出现，其延伸可达 100 μm，但完全相干，并表现出稳定的空间结构，一次可稳定几分钟。这些状态表现出由于在由光势能定义的圆形波导中反向传播的两个超流体的相互作用而产生的花瓣状强度分布。与传统激光系统中的环形模式形成鲜明对比的是，所得的驻波模式与泵浦激光本身的重叠最小。我们使用复金兹堡-朗道方程理论上描述了该系统，该方程指出了凝聚态想要旋转的原因。实验上，我们通过仔细修改激发几何形状以及在超快时间尺度上对系统进行微扰来证明能够精确控制花瓣凝聚态的结构，从而揭示出意想不到的超流动力学。
