High-speed integrated QKD system

Abstract

Quantum key distribution (QKD) is nowadays a well-established method for generating secret keys at a distance in an information-theoretically secure way, as the secrecy of QKD relies on the laws of quantum physics and not on computational complexity. In order to industrialize QKD, low-cost, mass-manufactured, and practical QKD setups are required. Hence, photonic and electronic integration of the sender’s and receiver’s respective components is currently in the spotlight. Here we present a high-speed (2.5 GHz) integrated QKD setup featuring a transmitter chip in silicon photonics allowing for high-speed modulation and accurate state preparation, as well as a polarization-independent low-loss receiver chip in aluminum borosilicate glass fabricated by the femtosecond laser micromachining technique. Our system achieves raw bit error rates, quantum bit error rates, and secret key rates equivalent to a much more complex state-of-the-art setup based on discrete components [ Boaron A. et al. , Phys. Rev. Lett. 121, 190502 (2018)].

Research progress in quantum key distribution

“…[85] Swiss and Italian scientists jointly developed a high-speed integrated QKD system. [86] Table 2 shows the research progress of silicon-based QKD.…”

Design and implementation of a polarization-encoding system for quantum key distribution

“…This subsystem influences the error-rates and, therefore, the reachable distance and secret key rates [14]. Several state of polarization (SOP) generation methods have been proposed, for example, using balanced Mach-Zehnder interferometers [15,16], or fiber-based Sagnac loops [17], among others. However, even though the Mach-Zehnder scheme is simple to implement, it is highly unstable because of its sensitivity to environmental perturbations [18].…”

Mode-pairing quantum key distribution based on wavelength division multiplexing in multi-user networks

“…QKD also strives for miniaturization [24,25] and networking capabilities [26][27][28][29] in addition to distance and security. Such a network necessitates both an extended communication distance and the ability to support multi-user concurrent communication.…”