Creation of partially rotating vortex of polariton condensate by non-resonant Laguerre-Gaussian optical excitation in semiconductor microcavity*

An exciton-polariton is a bosonic quasi-particle formed by a strong coupling between a quantum well exciton and a cavity photon in a semiconductor microcavity. Its bosonic nature offers the ground state condensation and superfluidity that hosts quantized vortices generated by various optical excitation methods. Here, we observed a new method for creating quantized vortices in the polariton superfluid whose vorticity is determine by the orbital angular momentum of a non-resonant Laguerre-Gaussian optical excitation.[1] Moreover, the polariton condensate is found to be in two different energy states, a vortex carrying excited state and the irrotational ground state, which is confirmed by the tomographic interferometer.[2] As a result, only a part of superfluid is found to be rotating with a vortex core and the fraction of the rotating superfluid can be controlled by changing the excitation beam size or the pumping power. This striking observation will be helpful for improving our understanding of relaxation process and non-equilibrium physics in semiconductor and non-equilibrium superfluid.
[1] M.-S. Kwon, B. Y. Oh et al., Physical Review Letters 122, 045302 (2019)
[2] D. Choi et al., ArXiv preprint ArXiv:1909.02241 (2019)