High-Speed Measurement-Device-Independent Quantum Key Distribution with Integrated Silicon Photonics

Kejin Wei,Lixing You,Yang Li,Feihu Xu,Hao Min,Hao Tan,Cheng-Zhi Peng,Hao Li,Sheng-Kai Liao,Teng-Yun Chen,Wei Li,Jian-Wei Pan,Xiao Jiang,Zhen Wang,Wei-Jun Zhang

doi:10.1103/physrevx.10.031030

Abstract

Measurement-device-independent quantum key distribution (MDI-QKD) removes all detector side channels and enables secure QKD with an untrusted relay. It is suitable for building a star-type quantum access network, where the complicated and expensive measurement devices are placed in the central untrusted relay and each user requires only a low-cost transmitter, such as an integrated photonic chip. Here, we experimentally demonstrate a 1.25 GHz silicon photonic chip-based MDI-QKD system using polarization encoding. The photonic chip transmitters integrate the necessary encoding components for a standard QKD source. We implement random modulations of polarization states and decoy intensities, and demonstrate a finite-key secret rate of 31 bps over 36 dB channel loss (or 180 km standard fiber). This key rate is higher than state-of-the-art MDI-QKD experiments. The results show that silicon photonic chip-based MDI-QKD, benefiting from miniaturization, low-cost manufacture and compatibility with CMOS microelectronics, is a promising solution for future quantum secure networks.

Highlights

Quantum key distribution (QKD) [1,2] is a key technology for building nodal networks which are believed to be a crucial stepping stone toward a quantum Internet
The bandwidth of the carrier-depletion modulators (CDMs) reaches about 21 GHz which is measured by using a vector network analyzer
The performance of the chip is sufficient for a low-error, high-rate Measurement-device-independent quantum key distribution (MDI QKD)

Summary

INTRODUCTION

Quantum key distribution (QKD) [1,2] is a key technology for building nodal networks which are believed to be a crucial stepping stone toward a quantum Internet. In the chip-based MDI QKD network, each user only needs a compact transmitter chip, whereas the relay holds the expensive and bulky measurement system (and quantum memory [31]) which are shared by all users This structure can bypass the challenging technique for intergrading single-photon. We implement MDI QKD with random modulations of decoy intensities and polarization qubits, and demonstrate a finite-key secret rate of 31 bit=s over 36-dB channel loss. Alice and Bob each use a homemade cost-effective field-programmable gate array (FPGA) board (see Appendix C 3) to accomplish the electrical controls, including the laser driving, random modulation of intensity modulators (IMs) and polarization modulators (POLs), synchronization of different devices, etc.

RESULTS

DISCUSSIONS

Source

Si transmitter chip

Electronic control board

Detection