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 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.
- Received 19 February 2020
- Revised 29 April 2020
- Accepted 3 June 2020
DOI:https://doi.org/10.1103/PhysRevX.10.031030
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
Quantum key distribution (QKD) can provide secure communication between two remote parties based on the laws of quantum mechanics. The field of QKD has witnessed and supplied major contributions to the development of secure communication networks. Nonetheless, the existing QKD networks rely on trusted relays, which is a security drawback. Furthermore, these networks use bulky and high-cost equipment, which limit large-scale deployment of the QKD network. Here, we overcome these limitations by demonstrating a chip-based, measurement-device-independent (MDI) QKD system.
The combination of photonic chips and MDI QKD enables a remarkably new quantum network structure with an untrusted relay, where each user needs only a compact transmitter chip, whereas the centric relay holds the expensive and bulky measurement system shared by all users. Our silicon photonic chip transmitters integrate all the encoding components for a standard QKD source. We demonstrate a chip-based MDI QKD system at a record high speed of 1.25 GHz that can transfer secret keys at a rate that is higher than all previous MDI QKD experiments.
We believe that our system opens up a new avenue for a low-cost, scalable, and secure QKD network with untrusted relays. The high-speed implementation with the highest reported key rates pushes MDI QKD forward to real applications.
