Silicon photonic transmitter for polarization-encoded quantum key distribution

TLDR

Silicon photonics is creating a fabless ecosystem that enables low‑cost, densely integrated components for optical communications and quantum information, and the devices in the circuit meet the requirements for QKD. We present a Si optical transmitter for polarization‑encoded quantum key distribution (QKD). The chip, fabricated in a standard Si photonic foundry process, integrates a pulse generator, intensity modulator, variable optical attenuator, and polarization modulator on a 1.3 mm × 3 mm die and was used to demonstrate the BB84 QKD protocol over a 5 km fiber link. This work shows the potential of using foundry Si photonics for low‑cost, wafer‑scale fabricated components for quantum information.

Abstract

Silicon (Si) photonics is forming a fabless ecosystem, which is enabling low-cost and densely integrated components for optical communications and quantum information. We present a Si optical transmitter for polarization-encoded quantum key distribution (QKD). The chip was fabricated in a standard Si photonic foundry process and integrated together a pulse generator, intensity modulator, variable optical attenuator, and polarization modulator in a 1.3  mm×3  mm1.3  mm×3  mm die area. The devices in the photonic circuit meet the requirements for QKD. The transmitter was used in a proof-of-concept demonstration of the BB84 QKD protocol over a 5 km long fiber link. This work shows the potential of using foundry Si photonics for low-cost, wafer-scale fabricated components for quantum information.