A liquid crystal host-guest system composed of achiral organic molecules (host) and colored chiral metal complexes (guest) was fabricated to sense both right- and left-handed circularly polarized light (r- and l-CPL), depending on the guest (dopant) concentration. The CPL-sensing can be reversibly turned on and off upon mechanical stress and heating.

A new ruthenium complex that effectively induces chiral nematic and blue phases upon doping with a nematic liquid crystal was developed. The red-colored dopant exhibits strong Raman scattering in solution and nematics even at low concentrations. Further measurements at various concentrations strongly suggested homogeneous dispersion of the dopant in chiral nematics.

Long-distance quantum communication requires entanglement between distant quantum memories. For the purpose, photon transmission is necessary to connect the distant memories.Here, for the first time, we develop a two-step frequency conversion process (from a visible wavelength to a telecommunication wavelength and back) involving the use of independent two-frequency conversion media where target quantum memories are nitrogen-vacancy centers in diamonds (with an emission/absorption wavelength of 637.2 nm), and experimentally characterize the performance of this process acting on light from an attenuated CW laser. A total conversion efficiency of approximately 7% is achieved. The noise generated in the frequency conversion processes is measured, and the signal-to-noise ratio is estimated for a single photon signal emitted by an NV center. The developed frequency conversion system has future applications via transmission through long optical fiber channel at a telecommunication wavelength for quantum repeater network.

No abstract