3,4-Dihy­droxy­phenethyl acetate

In the title compound, C10H12O4, the dihedral angle between the acetate group and the aromatic ring is 20.47 (10)°. In the crystal, mol­ecules are linked by O—H⋯O hydrogen bonds, forming [001] chains. Weak C—H⋯O inter­actions consolidate the packing

1,2-Bis(4-methyl­phen­oxy)ethane

In the title compound, C16H18O2, the two aromatic rings are almost orthogonal, making a dihedral angle of 89.41 (2)°. There is a C—H⋯π contact between the methyl­ene group and the 4-methyl­phenyl ring. The molecule exhibits twofold symmetry.

Path Loss Model with Antenna Height Dependency under Indoor Stair Environment

A novel, receiving antenna-height-dependent path loss model under indoor stair environment is presented. The effect of a cross-beam in the stairs is also considered. The proposed model can be applied to describe both of the line-of-sight (LOS) and the non-LOS (NLOS) cases. By using least square criterion, the parameters of proposed model are extracted. Finally, using the maximum likelihood estimation, the precision of the proposed model is evaluated by the standard deviation of shadowing

Polarization-entangled quantum frequency comb

Integrated micro-resonator facilitates the realization of quantum frequency comb (QFC), which provides a large number of discrete frequency modes with broadband spectral range and narrow linewidth. However, all previous demonstrations have focused on the generation of energy-time or time-bin entangled photons from QFC. Realizing polarization-entangled quantum frequency comb, which is the important resource for fundamental study of quantum mechanics and quantum information applications, remains challenging. Here, we demonstrate, for the first time, a broadband polarization-entangled quantum frequency comb by combining an integrated silicon nitride micro-resonator with a Sagnac interferometer. With a free spectral range of about 99 GHz and a narrow linewidth of about 190 MHz, our source provides 22 polarization entangled photons pairs with frequency covering the whole telecom C-band. The entanglement fidelities for all 22 pairs are above 81%, including 17 pairs with fidelities higher than 90%. Our demonstration paves the way for employing the polarization-entangled quantum frequency comb in quantum network using CMOS technology as well as standard dense wavelength division multiplexing technology.Comment: 11 pages, 9 figure