Field test of quantum key distribution over aerial fiber based on simple and stable modulation

We have developed a simple time-bin phase encoding quantum key distribution system, using the optical injection locking technique. This setup incorporates both the merits of simplicity and stability in encoding, and the immunity to channel disturbance. We have demonstrated, to our knowledge, the longest field implementation of quantum key distribution over deployed aerial fiber with a distance of 87 km. During the 70-day field test, we achieved approximately a 1.0 kbps secure key rate with stable performance. Our work takes an important step toward widespread implementation of QKD systems in diverse and complex real-life scenarios.