Low-loss, dual-polarization asymmetric Mach-Zehnder interferometer chips for quantum key distribution

Low-loss, dual-polarization asymmetric Mach-Zehnder interferometer chips for quantum key distribution

연구 분야: Cryptography

학회: Science China Information Sciences

We have developed the first low-loss, dual-polarization, asymmetric Mach-Zehnder interferometer (AMZI) chip for phase-coding quantum key distribution (QKD) using silica planar lightwave circuit technology. The transmitter and receiver modules have a polarization extinction ratio greater than 20 and 15 dB, respectively. Using a birefringent Mach-Zehnder interferometer, a polarization beam splitter is integrated into the receiver chip, while the polarization rotation function is obtained via a half-wave plate thin film. The receiver chip is entirely passive and has an excellent fiber C fiber loss of 1.90 dB, while the transmitter’s AMZI contains thermo-optical electrodes for adjusting the output pulses’ relative phase and intensity ratio. The chips are evaluated to have an interference visibility of greater than 98% across a broad temperature range, demonstrating their suitability for quantum key distribution applications.