2018 Fiscal Year Annual Research Report
Structured complex potentials for designer topological systems and devices in optics
|Research Institution||Institute of Physical and Chemical Research |
樽茶 清悟 国立研究開発法人理化学研究所, 創発物性科学研究センター, 副センター長 (40302799)
|Foreign Research Fellow
DEL VALLE INCLAN REDONDO YAGO BALTASAR 国立研究開発法人理化学研究所, 創発物性科学研究センター, 外国人特別研究員
|Project Period (FY)
2018-11-09 – 2021-03-31
|Keywords||exciton-polariton / superfluidity / complex lattice / Haldane model / topological|
|Outline of Annual Research Achievements
The experimental control software was updated and implemented in Python, with much faster data
acquisition and easy implementation of complex experimental procedures. The setup was improved with the following additions: laser top-hat shaping and continuous control of beam size and collimation for controlling condensate shape; and an electro-optic modulator for fast switching and modulating of laser power.
Fabrication of structured complex potential samples is being done by a new dedicated member of
staff. Concurrently, we have continued experiments on the superfluid nature of polariton condensates: large, uniform, quasi-CW condensates are perturbed with a non-resonant, pulsed
excitation, and the long-range transport of superfluid excitations on top of the condensate is
|Current Status of Research Progress
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Fabrication process is on track, and we should have new samples within the next 6 weeks.
Currently finishing the measurements on polariton superfluidity. There have been three obstacles so far in creating temporally-stable, spatially-uniform, large-scale condensates. The first has been sample non-uniformity, for which two approaches are being followed: the first is to automate the search of uniform sample regions, while the second is using micropillars where the spatial confinement should improve the condensate uniformity. The second is the power-stability of the CW laser, for which monitoring electronics are being added. The final problem has been heating of the sample due to long laser exposures. Acousto-optic modulators are being introduced to provide faster, quasi-CW pulses.
|Strategy for Future Research Activity
Once the first samples are fabricated, we will start the spectroscopic characterization of them and
start experiments measuring the condensation of polaritons inside potential lattices. Spatial light modulators will be added to provide control of the condensation potential.
Concurrently, we will perform experiments measuring the relaxation constants and processes in our samples, which is necessary to provide fast, non-resonant control of polariton condensates. We are also in the process of fabricating samples with dissipative coupling. There is numerical evidence that these structures support time-reversal symmetry broken steady states. Further analytical understanding of these structures is underway, and it will provide the basis for creating large-scale complex lattices.