Circular-polarization sensitive metamaterial based on triple quantum-dot   molecules
  We propose a new type of a chiral metamaterial based on an ensemble of artificial molecules formed by three identical quantum-dots in a triangular arrangement. A static magnetic field oriented perpendicular to the plane breaks mirror symmetry, rendering the molecules sensitive to the circular polarization of light. By varying the orientation and magnitude of the magnetic field one can control the polarization and frequency of the emission spectrum. We identify a threshold frequency, {\Omega}, above which we find strong birefringence. In addition, a Kerr rotation and circularly polarized lasing action can be implemented. We investigate the single-molecule lasing properties for different energy-level arrangements and demonstrate the possibility of circular polarization conversion. Finally, we analyze the effect of weak stray electric fields or deviations from the equilateral triangular geometry. 
Panagiotis Kotetes, Pei-Qing Jin, Michael Marthaler, Gerd Sch\"on
cond-mat.mes-hall