  Silicon single-photon detectors (SPDs) are the key devices for detecting
single photons in the visible wavelength range. Here we present high detection
efficiency silicon SPDs dedicated to the generation of multiphoton entanglement
based on the technique of high-frequency sine wave gating. The silicon
single-photon avalanche diodes (SPADs) components are acquired by disassembling
6 commercial single-photon counting modules (SPCMs). Using the new quenching
electronics, the average detection efficiency of SPDs is increased from 68.6%
to 73.1% at a wavelength of 785 nm. These sine wave gating SPDs are then
applied in a four-photon entanglement experiment, and the four-fold coincidence
count rate is increased by 30% without degrading its visibility compared with
the original SPCMs.
