Differential Phase Shift Quantum Key Distribution in Telecom Band

Yung Cheng Kao^1*, Sheng-Hsuan Huang¹, Chih-Hsiang Wu¹, Chin-Sung Chuu¹

¹物理系, 國立清華大學, 新竹市, Taiwan

* Presenter:Yung Cheng Kao, email:x4862x2000@gmail.com

Quantum key distribution (QKD) promises an absolutely secure communication channel based on the principles of quantum mechanics. In this work, we demonstrate the differential phase shift (DPS) QKD in the 1550 nm wavelength range, which has lower loss in optical fiber compared to other wavelength bands. On the sender’s (Alice’s) side, we attenuate a pulse train of light to single-photon level and encrypt the bit information in the phase difference between adjacent pulses. On the receiver’s (Bob’s) side, we use single photon detectors at the exits of an imbalanced Mach-Zehnder interferometer to decrypt the bit information. The key distribution is completed after Bob reveals the arrival times of all detected photons to Alice.

Keywords: Quantum Key Distribution, Differential Phase Shift